(a) Certain material is incorporated by reference into this subpart with the approval of the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other than that specified in this section, the U.S. Department of Energy (DOE) must publish a document in the Federal Register and the material must be available to the public. All approved incorporation by reference (IBR) material is available for inspection at DOE, and at the National Archives and Records Administration (NARA). Contact DOE at: the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Building Technologies Program, Sixth Floor, 950 L'Enfant Plaza SW, Washington, DC 20024, (202) 586-9127, [email protected], www.energy.gov/eere/buildings/building-technologies-office. For information on the availability of this material at NARA, email: [email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html. The material may be obtained from the sources in the following paragraphs of this section.

(b) AHRI. Air-Conditioning, Heating, and Refrigeration Institute, 2111 Wilson Boulevard, Suite 500, Arlington, VA 22201; (703) 600-0366; www.ahrinet.org.

(1) ANSI/AHRI Standard 420-2008 (“AHRI 420-2008”), Performance Rating of Forced-Circulation Free-Delivery Unit Coolers for Refrigeration, Copyright 2008; IBR approved for appendix C to subpart R.

(2) AHRI Standard 1250P (I-P)-2009 (“AHRI 1250-2009”), Standard for Performance Rating of Walk-in Coolers and Freezers, (including Errata sheet dated December 2015), copyright 2009, except Table 15 and Table 16; IBR approved for appendix C to subpart R.

(3) AHRI Standard 1250 (“AHRI 1250-2020”), Standard for Performance Rating of Walk-in Coolers and Freezers, copyright 2020; IBR approved for appendix C1 to subpart R.

(c) ASHRAE. American Society of Heating, Refrigerating and Air-Conditioning Engineers, 180 Technology Parkway, Peachtree Corners, GA 30092; (404) 636-8400; www.ashrae.org.

(1) ANSI/ASHRAE Standard 16-2016 (“ANSI/ASHRAE 16”), Method of Testing for Rating Room Air Conditioners, Packaged Terminal Air Conditioners, and Packaged Terminal Heat Pumps for Cooling and Heating Capacity, ANSI-approved November 1, 2016; IBR approved for appendix C1 to subpart R.

(2) ANSI/ASHRAE Standard 23.1-2010 (“ASHRAE 23.1-2010”), Methods of Testing for Rating the Performance of Positive Displacement Refrigerant Compressors and Condensing Units that Operate at Subcritical Temperatures of the Refrigerant, ANSI-approved January 28, 2010; IBR approved for appendices C and C1 to subpart R.

(3) ANSI/ASHRAE Standard 37-2009 (“ANSI/ASHRAE 37”), Methods of Testing for Rating Electrically Driven Unitary Air-Conditioning and Heat Pump Equipment, ASHRAE-approved June 24, 2009; IBR approved for appendices C and C1 to subpart R.

(4) ANSI/ASHRAE Standard 41.1-2013 (“ANSI/ASHRAE 41.1”), Standard Method for Temperature Measurement, ANSI-approved January 30, 2013; IBR approved for appendix C1 to subpart R.

(5) ANSI/ASHRAE Standard 41.3-2014 (“ANSI/ASHRAE 41.3”), Standard Methods for Pressure Measurement, ANSI-approved July 3, 2014; IBR approved for appendix C1 to subpart R.

(6) ANSI/ASHRAE Standard 41.6-2014 (“ANSI/ASHRAE 41.6”), Standard Method for Humidity Measurement, ANSI-approved July 3, 2014; IBR approved for appendix C1 to subpart R.

(7) ANSI/ASHRAE Standard 41.10-2013 (“ANSI/ASHRAE 41.10”), Standard Methods for Refrigerant Mass Flow Measurement Using Flowmeters, ANSI-approved June 27, 2013; IBR approved for appendix C1 to subpart R.

(d) ASTM. ASTM, International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959; (610) 832-9500; www.astm.org.

(1) ASTM C518-17, Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus, approved May 1, 2017; IBR approved for appendix B to subpart R.

(2) ASTM C1199-14, Standard Test Method for Measuring the Steady-State Thermal Transmittance of Fenestration Systems Using Hot Box Methods, approved February 1, 2014; IBR approved for appendix A to subpart R.

(e) NFRC. National Fenestration Rating Council, 6305 Ivy Lane, Ste. 140, Greenbelt, MD 20770; (301) 589-1776; www.nfrc.org/.

(1) NFRC 102-2020 [E0A0] (“NFRC 102-2020”), Procedure for Measuring the Steady-State Thermal Transmittance of Fenestration Systems, copyright 2013; IBR approved for appendix A to subpart R.

(2) [Reserved]

(a) Scope. This section provides test procedures for measuring, pursuant to EPCA, the energy consumption of walk-in coolers and walk-in freezers.

(b) Testing and calculations. Determine the energy efficiency and/or energy consumption of the specified walk-in cooler and walk-in freezer components by conducting the appropriate test procedure as follows:

(1) Display panels. Determine the energy use of walk-in cooler and walk-in freezer display panels by conducting the test procedure set forth in appendix A to this subpart.

(2) Display doors and non-display doors. Determine the energy use of walk-in cooler and walk-in freezer display doors and non-display doors by conducting the test procedure set forth in appendix A to this subpart.

(3) Non-display panels and non-display doors. Determine the R-value of insulation of walk-in cooler and walk-in freezer non-display panels and non-display doors by conducting the test procedure set forth in appendix B to this subpart.

(4) Refrigeration systems. Determine the AWEF and net capacity of walk-in cooler and walk-in freezer refrigeration systems by conducting the test procedures set forth in appendix C or C1 to this subpart, as applicable. Refer to the notes at the beginning of those appendices to determine the applicable appendix to use for testing.

(i) For unit coolers: follow the general testing provisions in sections 3.1 and 3.2, and the equipment-specific provisions in section 3.3 of appendix C or sections 4.5 through 4.8 of appendix C1.

(ii) For dedicated condensing units: follow the general testing provisions in sections 3.1 and 3.2, and the product-specific provisions in section 3.4 of appendix C or sections 4.5 through 4.8 of appendix C1.

(iii) For single-packaged dedicated systems: follow the general testing provisions in sections 3.1 and 3.2, and the product-specific provisions in section 3.3 of appendix C or sections 4.5 through 4.8 of appendix C1.

(a) Panel nameplate—(1) Required information. The permanent nameplate of a walk-in cooler or walk-in freezer panel for which standards are prescribed in § 431.306 must be marked clearly with the following information:

(i) The panel brand or manufacturer; and

(ii) One of the following statements, as appropriate:

(A) “This panel is designed and certified for use in walk-in cooler applications.”

(B) “This panel is designed and certified for use in walk-in freezer applications.”

(C) “This panel is designed and certified for use in walk-in cooler and walk-in freezer applications.”

(2) Display of required information. All orientation, spacing, type sizes, typefaces, and line widths to display this required information must be the same as or similar to the display of the other performance data included on the panel's permanent nameplate. The permanent nameplate must be visible unless the panel is assembled into a completed walk-in.

(b) Door nameplate—(1) Required information. The permanent nameplate of a walk-in cooler or walk-in freezer door for which standards are prescribed in § 431.306 must be marked clearly with the following information:

(i) The door brand or manufacturer; and

(ii) One of the following statements, as appropriate:

(A) “This door is designed and certified for use in walk-in cooler applications.”

(B) “This door is designed and certified for use in walk-in freezer applications.”

(C) “This door is designed and certified for use in walk-in cooler and walk-in freezer applications.”

(2) Display of required information. All orientation, spacing, type sizes, typefaces, and line widths to display this required information must be the same as or similar to the display of the other performance data included on the door's permanent nameplate. The permanent nameplate must be visible unless the door is assembled into a completed walk-in.

(c) Refrigeration system nameplate—(1) Required information. The permanent nameplate of a walk-in cooler or walk-in freezer refrigeration system for which standards are prescribed in § 431.306 must be marked clearly with the following information:

(i) The refrigeration system brand or manufacturer;

(ii) The refrigeration system model number;

(iii) The date of manufacture of the refrigeration system (if the date of manufacture is embedded in the unit's serial number, then the manufacturer of the refrigeration system must retain any relevant records to discern the date from the serial number);

(iv) If the refrigeration system is a dedicated condensing refrigeration system, and is not designated for outdoor use, the statement, “Indoor use only” (for a matched pair this must appear on the condensing unit); and

(v) One of the following statements, as appropriate:

(A) “This refrigeration system is designed and certified for use in walk-in cooler applications.”

(B) “This refrigeration system is designed and certified for use in walk-in freezer applications.”

(C) “This refrigeration system is designed and certified for use in walk-in cooler and walk-in freezer applications.”

(2) Process cooling refrigeration systems. The permanent nameplate of a process cooling refrigeration system (as defined in § 431.302) must be marked clearly with the statement, “This refrigeration system is designed for use exclusively in walk-in cooler and walk-in freezer process cooling refrigeration applications.”

(3) Display of required information. All orientation, spacing, type sizes, typefaces, and line widths to display this required information must be the same as or similar to the display of the other performance data included on the refrigeration system's permanent nameplate. The model number must be in one of the following forms: “Model ______” or “Model number ______” or “Model No. ______.” The permanent nameplate must be visible unless the refrigeration system is assembled into a completed walk-in.

(d) A manufacturer may not mark the nameplate of a component with the required information if the manufacturer has not submitted a certification of compliance for the relevant model.

(e) Disclosure of efficiency information in marketing materials. Each catalog that lists the component and all materials used to market the component must include:

(1) For panels—The R-value in the form “R-value____.”

(2) For doors—The energy consumption in the form “EC____kWh/day.”

(3) For those refrigeration system for which standards are prescribed—The AWEF in the form “AWEF ____.”

(4) The information that must appear on a walk-in cooler or walk-in freezer component's permanent nameplate pursuant to paragraphs (a)-(c) of this section must also be prominently displayed in each catalog that lists the component and all materials used to market the component.

This subpart contains energy conservation requirements for walk-in coolers and walk-in freezers, pursuant to Part C of Title III of the Energy Policy and Conservation Act, as amended, 42 U.S.C. 6311-6317.

Adaptive defrost means a factory-installed defrost control system that reduces defrost frequency by initiating defrosts or adjusting the number of defrosts per day in response to operating conditions (e.g., moisture levels in the refrigerated space, measurements that represent coil frost load) rather than initiating defrost strictly based on compressor run time or clock time.

Attached split system means a matched pair refrigeration system which is designed to be installed with the evaporator entirely inside the walk-in enclosure and the condenser entirely outside the walk-in enclosure, and the evaporator and condenser are permanently connected with structural members extending through the walk-in wall.

Basic model means all components of a given type of walk-in cooler or walk-in freezer (or class thereof) manufactured by one manufacturer, having the same primary energy source, and which have essentially identical electrical, physical, and functional (or hydraulic) characteristics that affect energy consumption, energy efficiency, water consumption, or water efficiency; and

(1) With respect to panels, which do not have any differing features or characteristics that affect U-factor.

(2) [Reserved]

CO2 unit cooler means a unit cooler that includes a nameplate listing only CO2 as an approved refrigerant.

Dedicated condensing unit means a positive displacement condensing unit that is part of a refrigeration system (as defined in this section) and is an assembly that

(1) Includes 1 or more compressors, a condenser, and one refrigeration circuit; and

(2) Is designed to serve one refrigerated load.

Dedicated condensing refrigeration system means one of the following:

(1) A dedicated condensing unit;

(2) A single-package dedicated system; or

(3) A matched refrigeration system.

Detachable single-packaged dedicated system means a system consisting of a dedicated condensing unit and an insulated evaporator section in which the evaporator section is designed to be installed external to the walk-in enclosure and circulating air through the enclosure wall, and the condensing unit is designed to be installed either attached to the evaporator section or mounted remotely with a set of refrigerant lines connecting the two components.

Display door means a door that:

(1) Is designed for product display; or

(2) Has 75 percent or more of its surface area composed of glass or another transparent material.

Display panel means a panel that is entirely or partially comprised of glass, a transparent material, or both and is used for display purposes.

Door means an assembly installed in an opening on an interior or exterior wall that is used to allow access or close off the opening and that is movable in a sliding, pivoting, hinged, or revolving manner of movement. For walk-in coolers and walk-in freezers, a door includes the frame (including mullions), the door leaf or multiple leaves (including glass) within the frame, and any other elements that form the assembly or part of its connection to the wall.

Door leaf means the pivoting, rolling, sliding, or swinging portion of a door.

Door surface area means the product of the height and width of a walk-in door measured external to the walk-in. The height and width dimensions shall be perpendicular to each other and parallel to the wall or panel of the walk-in to which the door is affixed. The height and width measurements shall extend to the edge of the frame and frame flange (as applicable) to which the door is affixed. For sliding doors, the height and width measurements shall include the track; however, the width (for horizontal sliding doors) or the height (for vertical sliding doors) shall be truncated to the external width or height of the door leaf or leaves and its frame or casings. The surface area of a display door is represented as Add and the surface area of a non-display door is represented as And.

Ducted fan coil unit means an assembly, including means for forced air circulation capable of moving air against both internal and non-zero external flow resistance, and elements by which heat is transferred from air to refrigerant to cool the air, with provision for ducted installation.

Ducted multi-circuit single-packaged dedicated system means a ducted single-packaged dedicated system or a ducted single-packaged dedicated system (as defined in this section) that contains two or more refrigeration circuits that refrigerate a single stream of circulated air.

Ducted single-packaged dedicated system means a refrigeration system (as defined in this section) that is a single-packaged assembly designed for use with ducts, that includes one or more compressors, a condenser, a means for forced circulation of refrigerated air, and elements by which heat is transferred from air to refrigerant.

Envelope means—

(1) The portion of a walk-in cooler or walk-in freezer that isolates the interior, refrigerated environment from the ambient, external environment; and

(2) All energy-consuming components of the walk-in cooler or walk-in freezer that are not part of its refrigeration system.

Freight door means a door that is not a display door and is equal to or larger than 4 feet wide and 8 feet tall.

High-temperature refrigeration system means a refrigeration system which is not designed to operate below 45 °F.

Indoor dedicated condensing refrigeration system means a dedicated condensing refrigeration system designated by the manufacturer for indoor use or for which there is no designation regarding the use location.

K-factor means the thermal conductivity of a material.

Manufacturer of a walk-in cooler or walk-in freezer means any person who:

(1) Manufactures a component of a walk-in cooler or walk-in freezer that affects energy consumption, including, but not limited to, refrigeration, doors, lights, windows, or walls; or

(2) Manufactures or assembles the complete walk-in cooler or walk-in freezer.

Matched condensing unit means a dedicated condensing unit that is distributed in commerce with one or more unit cooler(s) specified by the condensing unit manufacturer.

Matched refrigeration system (also called “matched-pair”) means a refrigeration system including the matched condensing unit and the one or more unit coolers with which it is distributed in commerce.

Multi-circuit single-packaged dedicated system means a single-packaged dedicated system or a ducted single-packaged dedicated system (as defined in this section) that contains two or more refrigeration circuits that refrigerate a single stream of circulated air.

Non-display door means a door that is not a display door.

Outdoor dedicated condensing refrigeration system means a dedicated condensing refrigeration system designated by the manufacturer for outdoor use.

Panel means a construction component that is not a door and is used to construct the envelope of the walk-in, i.e., elements that separate the interior refrigerated environment of the walk-in from the exterior.

Passage door means a door that is not a freight or display door.

Refrigerated means held at a temperature at or below 55 degrees Fahrenheit using a refrigeration system.

Refrigerated storage space means a space held at refrigerated (as defined in this section) temperatures.

Refrigeration system means the mechanism (including all controls and other components integral to the system's operation) used to create the refrigerated environment in the interior of a walk-in cooler or walk-in freezer, consisting of:

(1) A dedicated condensing refrigeration system (as defined in this section); or

(2) A unit cooler.

Single-packaged dedicated system means a refrigeration system (as defined in this section) that is a single-package assembly that includes one or more compressors, a condenser, a means for forced circulation of refrigerated air, and elements by which heat is transferred from air to refrigerant, without any element external to the system imposing resistance to flow of the refrigerated air.

U-factor means the heat transmission in a unit time through a unit area of a specimen or product and its boundary air films, induced by a unit temperature difference between the environments on each side.

Unit cooler means an assembly, including means for forced air circulation and elements by which heat is transferred from air to refrigerant, thus cooling the air, without any element external to the cooler imposing air resistance.

Walk-in cooler and walk-in freezer means an enclosed storage space including, but not limited to, panels, doors, and refrigeration system, refrigerated to temperatures, respectively, above, and at or below 32 degrees Fahrenheit that can be walked into, and has a total chilled storage area of less than 3,000 square feet; however, the terms do not include products designed and marketed exclusively for medical, scientific, or research purposes.

Walk-in process cooling refrigeration system means a refrigeration system that is capable of rapidly cooling food or other substances from one temperature to another. The basic model of such a system must satisfy one of the following three conditions:

(1) Be distributed in commerce with an insulated enclosure consisting of panels and door(s) such that the assembled product has a refrigerating capacity of at least 100 Btu/h per cubic foot of enclosed internal volume;

(2) Be a unit cooler having an evaporator coil that is at least four-and-one-half (4.5) feet in height and whose height is at least one-and-one-half (1.5) times the width. The height of the evaporator coil is measured perpendicular to the tubes and is also the fin height, while its width is the finned length parallel to the tubes, as illustrated in Figure 1; or

(3) Be a dedicated condensing unit that is distributed in commerce exclusively with a unit cooler meeting description (2) or with an evaporator that is not a unit cooler, i.e., an evaporator that is not distributed or installed as part of a package including one or more fans.

(a) Each walk-in cooler or walk-in freezer manufactured on or after January 1, 2009, shall—

(1) Have automatic door closers that firmly close all walk-in doors that have been closed to within 1 inch of full closure, except that this paragraph shall not apply to doors wider than 3 feet 9 inches or taller than 7 feet;

(2) Have strip doors, spring hinged doors, or other method of minimizing infiltration when doors are open;

(3) Contain wall, ceiling, and door insulation of at least R-25 for coolers and R-32 for freezers, except that this paragraph shall not apply to:

(i) Glazed portions of doors not to structural members and

(ii) A walk-in cooler or walk-in freezer component if the component manufacturer has demonstrated to the satisfaction of the Secretary in a manner consistent with applicable requirements that the component reduces energy consumption at least as much as if such insulation requirements of subparagraph (a)(3) were to apply.

(4) Contain floor insulation of at least R-28 for freezers;

(5) For evaporator fan motors of under 1 horsepower and less than 460 volts, use—

(i) Electronically commutated motors (brushless direct current motors); or

(ii) 3-phase motors;

(6) For condenser fan motors of under 1 horsepower, use—

(i) Electronically commutated motors (brushless direct current motors);

(ii) Permanent split capacitor-type motors; or

(iii) 3-phase motors; and

(7) For all interior lights, use light sources with an efficacy of 40 lumens per watt or more, including ballast losses (if any), except that light sources with an efficacy of 40 lumens per watt or less, including ballast losses (if any), may be used in conjunction with a timer or device that turns off the lights within 15 minutes of when the walk-in cooler or walk-in freezer is not occupied by people.

(b) Each walk-in cooler or walk-in freezer with transparent reach-in doors manufactured on or after January 1, 2009, shall also meet the following specifications:

(1) Transparent reach-in doors for walk-in freezers and windows in walk-in freezer doors shall be of triple-pane glass with either heat-reflective treated glass or gas fill.

(2) Transparent reach-in doors for walk-in coolers and windows in walk-in cooler doors shall be—

(i) Double-pane glass with heat-reflective treated glass and gas fill; or

(ii) Triple-pane glass with either heat-reflective treated glass or gas fill.

(3) If the walk-in cooler or walk-in freezer has an antisweat heater without antisweat heat controls, the walk-in cooler and walk-in freezer shall have a total door rail, glass, and frame heater power draw of not more than 7.1 watts per square foot of door opening (for freezers) and 3.0 watts per square foot of door opening (for coolers).

(4) If the walk-in cooler or walk-in freezer has an antisweat heater with antisweat heat controls, and the total door rail, glass, and frame heater power draw is more than 7.1 watts per square foot of door opening (for freezers) and 3.0 watts per square foot of door opening (for coolers), the antisweat heat controls shall reduce the energy use of the antisweat heater in a quantity corresponding to the relative humidity in the air outside the door or to the condensation on the inner glass pane.

(c) Walk-in cooler and freezer display doors. All walk-in cooler and walk-in freezer display doors manufactured starting June 5, 2017, must satisfy the following standards:

(d) Walk-in cooler and freezer non-display doors. All walk-in cooler and walk-in freezer non-display doors manufactured starting on June 5, 2017, must satisfy the following standards:

(e) Walk-in cooler refrigeration systems. All walk-in cooler and walk-in freezer refrigeration systems manufactured starting on the dates listed in the table, except for walk-in process cooling refrigeration systems (as defined in § 431.302), must satisfy the following standards:

DOE incorporated by reference in § 431.303 the entire standard for ASTM C1199-14 and NFRC 102-2020. However, certain enumerated provisions of these standards, as set forth in sections 0.1 and 0.2 of this appendix are inapplicable. To the extent that there is a conflict between the terms or provisions of a referenced industry standard and the CFR, the CFR provisions control.

(a) Section 1 Scope, is inapplicable,

(b) Section 4 Significance and Use is inapplicable,

(c) Section 7.3 Test Conditions, is inapplicable,

(d) Section 10 Report, is inapplicable, and

(e) Section 11 Precision and Bias, is inapplicable.

(a) Section 1 Scope, is inapplicable,

(b) Section 4 Significance and Use, is inapplicable,

(c) Section 7.3 Test Conditions, is inapplicable,

(d) Section 10 Report, is inapplicable,

(e) Section 11 Precision and Bias, is inapplicable,

(f) Annex A3 Standard Test Method for Determining the Thermal Transmittance of Tubular Daylighting Devices, is inapplicable, and

(g) Annex A5 Tables and Figures, is inapplicable.

This appendix covers the test requirements used to measure the energy consumption of the components that make up the envelope of a walk-in cooler or walk-in freezer.

The definitions contained in § 431.302 are applicable to this appendix.

4.1 Automatic door opener/closer means a device or control system that “automatically” opens and closes doors without direct user contact, such as a motion sensor that senses when a forklift is approaching the entrance to a door and opens it, and then closes the door after the forklift has passed.

4.2 Percent time off (PTO) means the percent of time that an electrical device is assumed to be off.

4.3 Rated power means the input power of an electricity-consuming device as specified on the device's nameplate. If the device does not have a nameplate or such nameplate does not list the device's input power, then the rated power must be determined from the device's product data sheet, literature, or installation instructions that come with the device or are available online.

4.4 Rating conditions means, unless explicitly stated otherwise, all conditions shown in table A.1 of this appendix.

Determine the U-factor of the entire door or display panel, including the frame, in accordance with the specified sections of NFRC 102-2020 and ASTM C1199-14 at the temperature conditions listed in table A.1 of this appendix.

5.2.1 For display doors and display panels, thermal transmittance, Udd or Udp, respectively, shall be the standardized thermal transmittance, UST, determined per section 5.1 of this appendix.

5.2.2 For non-display doors, thermal transmittance, Und, shall be the standardized thermal transmittance, UST, determined per section 5.1 of this appendix.

5.2.3 Projected area of the test specimen, As, in ft 2, as referenced in ASTM C1199-14.

6.1.1 Determine the U-factor of the display panel in accordance with section 5.1 of this appendix, in units of Btu/(h-ft 2- °F).

6.1.2 Calculate the temperature differential, ΔTdp, °F, for the display panel, as follows:

6.1.3 Calculate the conduction load through the display panel, Qcond-dp, Btu/h, as follows:

6.1.4 Calculate the total daily energy consumption, Edp, kWh/day, as follows:

6.2.1.1 Determine the U-factor of the display door in accordance with section 5.1 of this appendix, in units of Btu/(h-ft 2- °F).

6.2.1.2 Calculate the temperature differential, ΔTdd, °F, for the display door as follows:

6.2.1.3 Calculate the conduction load through the display doors, Qcond,dd, Btu/h, as follows:

6.2.1.4 Calculate the total daily energy consumption due to conduction thermal load, Edd,thermal, kWh/day, as follows:

Electrical components associated with display doors could include but are not limited to: heater wire (for anti-sweat or anti-freeze application); lights; door motors; control system units; and sensors.

6.2.2.1 Select the required value for percent time off (PTO) for each type of electricity-consuming device per table A.2 of this appendix, PTOt (%).

6.2.2.2 Calculate the power usage for each type of electricity-consuming device, Pdd,comp,u,t, kWh/day, as follows:

6.2.2.3 Calculate the total electrical energy consumption for interior and exterior power, Pdd,tot,int (kWh/day) and Pdd,tot,ext (kWh/day), respectively, as follows:

6.2.2.4 Calculate the total electrical energy consumption, Pdd,tot, (kWh/day), as follows:

Calculate the additional refrigeration energy consumption due to thermal output from electrical components sited inside the display door, Cdd,load, kWh/day, as follows:

Calculate the total energy, Edd,tot, kWh/day,

6.3.1.1 Determine the U-factor of the non-display door in accordance with section 5.1 of this appendix, in units of Btu/(h-ft 2- °F).

6.3.1.2 Calculate the temperature differential of the non-display door, ΔTnd, °F, as follows:

6.3.1.3 Calculate the conduction load through the non-display door: Qcond,nd, Btu/h,

6.3.1.4 Calculate the total daily energy consumption due to thermal load, End,thermal, kWh/day, as follows:

Electrical components associated with non-display doors comprise could include, but are not limited to: heater wire (for anti-sweat or anti-freeze application), lights, door motors, control system units, and sensors.

6.3.2.1 Select the required value for percent time off for each type of electricity-consuming device per table A.2 of this appendix, PTOt (%).

6.3.2.2 Calculate the power usage for each type of electricity-consuming device, Pnd,comp,u,t, kWh/day, as follows:

6.3.2.3 Calculate the total electrical energy consumption for interior and exterior power, Pnd,tot,int, kWh/day, and Pnd,tot,ext, kWh/day, respectively, as follows:

6.3.2.4 Calculate the total electrical energy consumption, Pnd,tot, kWh/day, as follows:

Calculate the additional refrigeration energy consumption due to thermal output from electrical components associated with the non-display door, Cnd,load, kWh/day, as follows:

Calculate the total energy, End,tot, kWh/day, as follows:

DOE incorporated by reference in § 431.303 the entire standard for ASTM C518-17. However, certain enumerated provisions of ASTM C518-17, as set forth in paragraph 0.1 of this appendix, are inapplicable. To the extent there is a conflict between the terms or provisions of a referenced industry standard and the CFR, the CFR provisions control.

(a) Section 1 Scope, is inapplicable,

(b) Section 4 Significance and Use, is inapplicable,

(c) Section 7.3 Specimen Conditioning, is inapplicable,

(d) Section 9 Report, is inapplicable,

(e) Section 10 Precision and Bias, is inapplicable,

(f) Section 11 Keywords, is inapplicable,

(g) Annex A2 Equipment Error Analysis, is inapplicable,

(h) Appendix X1 is inapplicable,

(i) Appendix X2 Response of Heat Flux Transducers, is inapplicable, and

(j) Appendix X3 Proven Performance of a Heat Flow Apparatus, is inapplicable.

The following sections of this appendix provide additional instructions for testing. In cases where there is a conflict, the language of this appendix takes highest precedence, followed by ASTM C518-17. Any subsequent amendment to a referenced document by the standard-setting organization will not affect the test procedure in this appendix, unless and until the test procedure is amended by DOE. Material is incorporated as it exists on the date of the approval, and a notification of any change in the incorporation will be published in the Federal Register.

This appendix covers the test requirements used to measure the R-value of non-display panels and non-display doors of a walk-in cooler or walk-in freezer.

The definitions contained in § 431.302 apply to this appendix.

4.1 Edge region means a region of the envelope component that is wide enough to encompass any framing members. If the envelope component contains framing members (e.g., a wood frame) then the width of the edge region must be as wide as any framing member plus an additional 2 in. ± 0.25 in.

5.1 General. Foam shall be tested after it is produced in its final chemical form. For foam produced inside of an envelope component (“foam-in-place”), “final chemical form” means the foam is cured as intended and ready for use as a finished envelope component. For foam produced as board stock (e.g., polystyrene), “final chemical form” means after extrusion and ready for assembly into an envelope component or after assembly into an envelope component. Foam must not include any structural members or non-foam materials during testing in accordance with ASTM C518-17. When preparing the specimen for test, a high-speed bandsaw or a meat slicer are two types of recommended cutting tools. Hot wire cutters or other heated tools shall not be used for cutting foam test specimens.

5.2.1 Determining the thickness around the perimeter of the envelope component, tp. The full thickness of an envelope component around the perimeter, which may include facers on one or both sides, shall be determined as follows:

5.2.1.1 At least 8 thickness measurements shall be taken around the perimeter of the envelope component, at least 2 inches from the edge region, and avoiding any regions with hardware or fixtures.

5.2.1.2 The average of the thickness measurements taken around the perimeter of the envelope component shall be the thickness around the perimeter of the envelope component, tp.

5.2.1.3 Measure and record the width, wp, and height, hp, of the envelope component. The surface area of the envelope component, Ap, shall be determined as follows:

5.2.2. Removing the sample from the envelope component.

5.2.2.1. Determine the center of the envelope component relative to its height and its width.

5.2.2.2. Cut a sample from the envelope component that is at least the length and width dimensions of the heat flow meter, and where the marked center of the sample is at least 3 inches from any cut edge.

5.2.2.3. If the center of the envelope component contains any non-foam components (excluding facers), additional samples may be cut adjacent to the previous cut that is at least the length and width dimensions of the heat flow meter and is greater than 12 inches from the edge region.

5.2.3. Determining the thickness at the center of the envelope component, tc. The full thickness of an envelope component at the center, which may include facers on one or both sides, shall be determined as follows:

5.2.3.1. At least 2 thickness measurements shall be taken in each quadrant of the cut sample removed from the envelope component per section 5.2.2 of this appendix, for a total of at least 8 measurements.

5.2.3.2. The average of the thickness measurements of the cut sample removed from the envelope component shall be the overall thickness of the cut sample, tc.

5.2.3.3. Measure and record the width and height of the cut sample removed from the envelope component. The surface area of the cut sample removed from the envelope component, Ac., shall be determined as follows:

5.2.4. Determining the total thickness of the foam within the envelope component, tfoam. The average total thickness of the foam sample, without facers, shall be determined as follows:

5.2.4.1. Remove the facers on the envelope component sample, while minimally disturbing the foam.

5.2.4.2. Measure the thickness of each facer in 4 locations for a total of 4 measurements if 1 facer is removed, and a total of 8 measurements if 2 facers are removed. The average of all facer measurements shall be the thickness of the facers, tfacers, in.

5.2.4.3. The average total thickness of the foam, tfoam, in., shall be determined as follows:

5.2.5. Cutting, measuring, and determining parallelism and flatness of a 1-inch-thick specimen for test from the center of the cut envelope component sample.

5.2.5.1. Cut a 1 ± 0.1-inch-thick specimen from the center of the cut envelope sample. The 1-inch-thick test specimen shall be cut from the point that is equidistant from both edges of the sample (i.e., shall be cut from the center point that would be directly between the interior and exterior space of the walk-in).

5.2.5.2. Document through measurement or photographs with measurement indicators that the specimen was taken from the center of the sample.

5.2.5.3 After the 1-inch specimen has been cut, and prior to testing, place the specimen on a flat surface and allow gravity to determine the specimen's position on the surface. This will be side 1.

5.2.5.4 To determine the flatness of side 1, take at least nine height measurements at equidistant positions on the specimen (i.e., the specimen would be divided into 9 regions and height measurements taken at the center of each of these nine regions). Contact with the measurement indicator shall not indent the foam surface. From the height measurements taken, determine the least squares plane for side 1. For each measurement location, calculate the theoretical height from the least squares plane for side 1. Then, calculate the difference between the measured height and the theoretical least squares plane height at each location. The maximum difference minus the minimum difference out of the nine measurement locations is the flatness of side 1. For side 1 of the specimen to be considered flat, this shall be less than or equal to 0.03 inches.

5.2.5.5 To determine the flatness of side 2, turn the specimen over and allow gravity to determine the specimen's position on the surface. Repeat section 5.2.5.4 to determine the flatness of side 2.

5.2.5.6 To determine the parallelism of the specimen for side 1, calculate the theoretical height of the least squares plane at the furthest corners (i.e., at points (0,0), (0,12), (12,0), and (12,12)) of the 12-inch by 12-inch test specimen. The difference between the maximum theoretical height and the minimum theoretical height shall be less than or equal to 0.03 inches for each side in order for side 1 to be considered parallel.

5.2.5.7 To determine the parallelism of the specimen for side 2, repeat section 5.2.5.6 of this appendix.

5.2.5.8 The average thickness of the test specimen, L, shall be 1 ± 0.1-inches determined using a minimum of 18 thickness measurements (i.e., a minimum of 9 measurements on side 1 of the specimen and a minimum of 9 on side 2 of the specimen). This average thickness shall be used to determine the thermal conductivity, or K-factor.

5.3 K-factor Test. Determine the thermal conductivity, or K-factor, of the 1-inch-thick specimen in accordance with the specified sections of ASTM C518-17. Testing must be completed within 24 hours of the specimen being cut for testing per section 5.2.5 of this appendix.

5.3.1 Test Conditions.

5.3.1.1 For freezer envelope components, the K-factor of the specimen shall be determined at an average specimen temperature of 20 ± 1 degrees Fahrenheit.

5.3.1.2 For cooler envelope components, the K-factor of the specimen shall be determined at an average specimen temperature of 55 ± 1 degrees Fahrenheit.

5.4 R-value Calculation.

5.4.1 For envelope components consisting of one homogeneous layer of insulation, calculate the R-value, h-ft 2- °F/Btu, as follows:

5.4.2 For envelope components consisting of two or more layers of dissimilar insulating materials (excluding facers or protective skins), determine the K-factor of each material as described in sections 5.1 through 5.3 of this appendix. For an envelope component with N layers of insulating material, the overall R-value shall be calculated as follows:

5.4.3 K-factor test results from a test sample 1 ± 0.1-inches in thickness may be used to determine the R-value of envelope components with various foam thicknesses as long as the foam throughout the panel depth is of the same final chemical form and the test was completed at the same test conditions that the other envelope components would be used at. For example, a K-factor test result conducted at cooler conditions cannot be used to determine R-value of a freezer envelope component.

This appendix covers the test requirements used to determine the net capacity and the AWEF of the refrigeration system of a walk-in cooler or walk-in freezer.

The definitions contained in § 431.302 and AHRI 1250-2009 (incorporated by reference; see § 431.303) apply to this appendix. When definitions contained in the standards DOE has incorporated by reference are in conflict or when they conflict with this section, the hierarchy of precedence shall be in the following order: § 431.302, AHRI 1250-2009, and then either AHRI 420-2008 (incorporated by reference; see § 431.303) for unit coolers or ASHRAE 23.1-2010 (incorporated by reference; see § 431.303) for dedicated condensing units.

The term “unit cooler” used in AHRI 1250-2009, AHRI 420-2008, and this subpart shall be considered to address both “unit coolers” and “ducted fan coil units,” as appropriate.

Determine the Annual Walk-in Energy Factor (AWEF) and net capacity of walk-in cooler and walk-in freezer refrigeration systems by conducting the test procedure set forth in AHRI 1250-2009 (incorporated by reference; see § 431.303), with the modifications to that test procedure provided in this section. When standards that are incorporated by reference are in conflict or when they conflict with this section, the hierarchy of precedence shall be in the following order: § 431.302, AHRI 1250-2009, and then either AHRI 420-2008 (incorporated by reference; see § 431.303) or ASHRAE 23.1-2010 (incorporated by reference; see § 431.303).

3.1. General modifications: Test Conditions and Tolerances.

When conducting testing in accordance with AHRI 1250-2009 (incorporated by reference; see § 431.303), the following modifications must be made.

3.1.1. In Table 1, Instrumentation Accuracy, refrigerant temperature measurements shall have an accuracy of ±0.5 °F for unit cooler in/out. When testing high-temperature refrigeration systems, measurements used to determine temperature or water vapor content of the air (i.e., wet-bulb or dew point) shall be accurate to within ±0.25 °F; all other temperature measurements shall be accurate to within ±1.0 °F.

3.1.2. In Table 2, Test Operating and Test Condition Tolerances for Steady-State Test, electrical power frequency shall have a Test Condition Tolerance of 1 percent.

3.1.3. In Table 2, the Test Operating Tolerances and Test Condition Tolerances for Air Leaving Temperatures shall be deleted.

3.1.4. In Tables 2 through 14, the Test Condition Outdoor Wet Bulb Temperature requirement and its associated tolerance apply only to units with evaporative cooling.

3.1.5. Tables 15 and 16 shall be modified to read as follows:

For medium-temperature CO2 unit coolers, conduct tests using the test conditions specified in table C.1 of this appendix. For low-temperature CO2 unit coolers, conduct tests using the test conditions specified in table C.2 of this appendix.

For high-temperature cooler unit coolers, conduct tests using the test conditions specified in table C.3 of this appendix.

When conducting testing in accordance with appendix C of AHRI 1250-2009 (incorporated by reference; see § 431.303), the following modifications must be made.

3.2.1. Refrigerant Temperature Measurements

In AHRI 1250-2009 appendix C, section C3.1.6, any refrigerant temperature measurements entering and leaving the unit cooler may use sheathed sensors immersed in the flowing refrigerant instead of thermometer wells. When testing a condensing unit alone, measure refrigerant liquid temperature leaving the condensing unit using thermometer wells as described in AHRI 1250-2009 appendix C, section C3.1.6 or sheathed sensors immersed in the flowing refrigerant. For all of these cases, if the refrigerant tube outer diameter is less than 1/2 inch, the refrigerant temperature may be measured using the average of two temperature measuring instruments with a minimum accuracy of ±0.5 °F placed on opposite sides of the refrigerant tube surface—resulting in a total of up to 8 temperature measurement devices used for the DX Dual Instrumentation method. In this case, the refrigerant tube shall be insulated with 1-inch thick insulation from a point 6 inches upstream of the measurement location to a point 6 inches downstream of the measurement location. Also, to comply with this requirement, the unit cooler entering measurement location may be moved to a location 6 inches upstream of the expansion device and, when testing a condensing unit alone, the entering and leaving measurement locations may be moved to locations 6 inches from the respective service valves.

3.2.2. It is not necessary to perform composition analysis of refrigerant (appendix C, section C3.3.6) or refrigerant oil concentration testing (appendix C, section C3.4.6).

3.2.3. Subcooling at Refrigerant Mass Flow Meter

In appendix C, section C3.4.5 of AHRI 1250-2009 (incorporated by reference; see § 431.303), and in section 7.1.2 of ASHRAE 23.1-2010 (incorporated by reference; see § 431.303) when verifying subcooling at the mass flow meters, only the sight glass and a temperature sensor located on the tube surface under the insulation are required. Subcooling shall be verified to be within the 3 °F requirement downstream of flow meters located in the same chamber as a condensing unit under test and upstream of flow meters located in the same chamber as a unit cooler under test, rather than always downstream as indicated in AHRI 1250-2009, section C3.4.5 or always upstream as indicated in section 7.1.2 of ASHRAE 23.1-2010. If the subcooling is less than 3 °F, cool the line between the condensing unit outlet and this location to achieve the required subcooling. When providing such cooling while testing a matched pair, (a) set up the line-cooling system and also set up apparatus to heat the liquid line between the mass flow meters and the unit cooler, (b) when the system has achieved steady state without activation of the heating and cooling systems, measure the liquid temperature entering the expansion valve for a period of at least 30 minutes, (c) activate the cooling system to provide the required subcooling at the mass flow meters, (d) if necessary, apply heat such that the temperature entering the expansion valve is within 0.5 0F of the temperature measured during step (b), and (e) proceed with measurements once condition (d) has been verified.

3.2.4. In appendix C, section C3.5, regarding unit cooler fan power measurements, for a given motor winding configuration, the total power input shall be measured at the highest nameplate voltage. For three-phase power, voltage imbalances shall be no more than 2 percent from phase to phase.

3.2.5. In the test setup (appendix C, section C8.3), the liquid line and suction line shall be constructed of pipes of the manufacturer-specified size. The pipe lines shall be insulated with a minimum total thermal resistance equivalent to 1/2-inch thick insulation having a flat-surface R-Value of 3.7 ft 2- °F-hr/Btu per inch or greater. Flow meters need not be insulated but must not be in contact with the floor. The lengths of the connected liquid line and suction line shall be 25 feet ± 3 inches, not including the requisite flow meters, each. Of this length, no more than 15 feet shall be in the conditioned space. Where there are multiple branches of piping, the maximum length of piping applies to each branch individually as opposed to the total length of the piping.

3.2.6. Installation Instructions

Manufacturer installation instructions refer to the instructions that are applied to the unit (i.e., as a label) or that come packaged with the unit. Online installation instructions are acceptable only if the version number or date of publication is referenced on the unit label or in the documents that are packaged with the unit.

3.2.6.1 Installation Instruction Hierarchy when available installation instructions are in conflict

3.2.6.1.1 If a manufacturer installation instruction provided on the label(s) applied to the unit conflicts with the manufacturer installation instructions that are shipped with the unit, the instructions on the unit's label take precedence.

3.2.6.1.2 Manufacturer installation instructions provided in any documents that are packaged with the unit take precedence over any manufacturer installation instructions provided online.

3.2.6.2 For testing of attached split systems, the manufacturer installation instructions for the dedicated condensing unit shall take precedence over the manufacturer installation instructions for the unit cooler.

3.2.6.3 Unit setup shall be in accordance with the manufacturer installation instructions (laboratory installation instructions shall not be used).

3.2.6.4 Achieving test conditions shall always take precedence over installation instructions.

3.2.7. Refrigerant Charging and Adjustment of Superheat and Subcooling.

All dedicated condensing systems (dedicated condensing units tested alone, matched pairs, and single packaged dedicated systems) that use flooding of the condenser for head pressure control during low-ambient-temperature conditions shall be charged, and superheat and/or subcooling shall be set, at Refrigeration C test conditions unless otherwise specified in the installation instructions.

If after being charged at Refrigeration C condition the unit under test does not operate at the Refrigeration A condition due to high pressure cut out, refrigerant shall be removed in increments of 4 ounces or 5 percent of the test unit's receiver capacity, whichever quantity is larger, until the unit operates at the Refrigeration A condition. All tests shall be run at this final refrigerant charge. If less than 0 °F of subcooling is measured for the refrigerant leaving the condensing unit when testing at B or C condition, calculate the refrigerant-enthalpy-based capacity (i.e., when using the DX dual instrumentation, the DX calibrated box, or single-packaged unit refrigerant enthalpy method) assuming that the refrigerant is at saturated liquid conditions at the condensing unit exit.

All dedicated condensing systems that do not use a flooded condenser design shall be charged at Refrigeration A test conditions unless otherwise specified in the installation instructions.

If the installation instructions give a specified range for superheat, sub-cooling, or refrigerant pressure, the average of the range shall be used as the refrigerant charging parameter target and the test condition tolerance shall be ±50 percent of the range. Perform charging of near-azeotropic and zeotropic refrigerants only with refrigerant in the liquid state. Once the correct refrigerant charge is determined, all tests shall run until completion without further modification.

3.2.7.1. When charging or adjusting superheat/subcooling, use all pertinent instructions contained in the installation instructions to achieve charging parameters within the tolerances. However, in the event of conflicting charging information between installation instructions, follow the installation instruction hierarchy listed in section 3.2.6. of this appendix. Conflicting information is defined as multiple conditions given for charge adjustment where all conditions specified cannot be met. In the event of conflicting information within the same set of charging instructions (e.g., the installation instructions shipped with the dedicated condensing unit), follow the hierarchy in table C.4 of this section for priority. Unless the installation instructions specify a different charging tolerance, the tolerances identified in table C.4 of this section shall be used.

3.2.7.2. Dedicated Condensing Unit. If the Dedicated Condensing Unit includes a receiver and the subcooling target leaving the condensing unit provided in installation instructions cannot be met without fully filling the receiver, the subcooling target shall be ignored. Likewise, if the Dedicated Condensing unit does not include a receiver and the subcooling target leaving the condensing unit cannot be met without the unit cycling off on high pressure, the subcooling target can be ignored. Also, if no instructions for charging or for setting subcooling leaving the condensing unit are provided in the installation instructions, the refrigeration system shall be set up with a charge quantity and/or exit subcooling such that the unit operates during testing without shutdown (e.g., on a high-pressure switch) and operation of the unit is otherwise consistent with the requirements of the test procedure of this appendix and the installation instructions.

3.2.8. Chamber Conditioning using the Unit Under Test.

In appendix C, section C6.2 of AHRI 1250-2009, for applicable system configurations (matched pairs, single-packaged refrigeration systems, and standalone unit coolers), the unit under test may be used to aid in achieving the required test chamber conditions prior to beginning any steady state test. However, the unit under test must be inspected and confirmed to be free from frost before initiating steady state testing.

3.3. Matched systems, single-package dedicated systems, and unit coolers tested alone: Use the test method in AHRI 1250-2009 (incorporated by reference; see § 431.303), appendix C as the method of test for matched refrigeration systems, single-package dedicated systems, or unit coolers tested alone, with the following modifications:

3.3.1. For unit coolers tested alone, use test procedures described in AHRI 1250-2009 for testing unit coolers for use in mix-match system ratings, except that for the test conditions in tables 15 and 16 of this appendix, use the Suction A saturation condition test points only. Also, for unit coolers tested alone, other than high-temperature unit coolers, use the calculations in section 7.9 of AHRI 1250-2009 to determine AWEF and net capacity described in AHRI 1250-2009 for unit coolers matched to parallel rack systems.

3.3.2. In appendix C, section C.13, the version of AHRI Standard 420 used for test methods, requirements, and procedures shall be AHRI 420-2008 (incorporated by reference; see § 431.303).

3.3.3. Evaporator Fan Power.

3.3.3.1. Ducted Evaporator Air.

For ducted fan coil units with ducted evaporator air, or that can be installed with or without ducted evaporator air: Connect ductwork on both the inlet and outlet connections and determine external static pressure as described in ASHRAE 37 (incorporated by reference; see § 431.303), sections 6.4 and 6.5. Use pressure measurement instrumentation as described in ASHRAE 37, section 5.3.2. Test at the fan speed specified in manufacturer installation instructions—if there is more than one fan speed setting and the installation instructions do not specify which speed to use, test at the highest speed. Conduct tests with the external static pressure equal to 50 percent of the maximum external static pressure allowed by the manufacturer for system installation within a tolerance of −0.00/+0.05 in. wc. Set the external static pressure by symmetrically restricting the outlet of the test duct. Alternatively, if using the indoor air enthalpy method to measure capacity, set external static pressure by adjusting the fan of the airflow measurement apparatus. In case of conflict, these requirements for setting evaporator airflow take precedence over airflow values specified in manufacturer installation instructions or product literature.

3.3.3.2. Unit Coolers or Single-Packaged Systems that are not High-Temperature Refrigeration Systems.

Use appendix C, section C10 of AHRI 1250-2009 for off-cycle evaporator fan testing, with the exception that evaporator fan controls using periodic stir cycles shall be adjusted so that the greater of a 50 percent duty cycle (rather than a 25 percent duty cycle) or the manufacturer default is used for measuring off-cycle fan energy. For adjustable-speed controls, the greater of 50 percent fan speed (rather than 25 percent fan speed) or the manufacturer's default fan speed shall be used for measuring off-cycle fan energy. Also, a two-speed or multi-speed fan control may be used as the qualifying evaporator fan control. For such a control, a fan speed no less than 50 percent of the speed used in the maximum capacity tests shall be used for measuring off-cycle fan energy.

3.3.3.3. High-Temperature Refrigeration Systems.

3.3.3.3.1. The evaporator fan power consumption shall be measured in accordance with the requirements in section C3.5 of AHRI 1250-2009. This measurement shall be made with the fan operating at full speed, either measuring unit cooler or total system power input upon the completion of the steady state test when the compressor and the condenser fan of the walk-in system are turned off, or by submetered measurement of the evaporator fan power during the steady state test.

Section C3.5 of AHRI 1250-2009 is revised to read:

Evaporator Fan Power Measurement.

The following shall be measured and recorded during a fan power test.

For a given motor winding configuration, the total power input shall be measured at the highest nameplate voltage. For three-phase power, voltage imbalance shall be no more than 2%.

3.3.3.3.2. Evaporator fan power for the off-cycle is equal to the on-cycle evaporator fan power with a run time of 10 percent of the off-cycle time.

3.3.4. Use appendix C, section C11 of AHRI 1250-2009 (incorporated by reference, see § 431.303) for defrost testing. The Frost Load Condition Defrost Test (C11.1.1) is optional.

3.3.4.1. If the frost load condition defrost test is performed:

3.3.4.1.1 Operate the unit cooler at the dry coil conditions as specified in appendix C, section C11.1 to obtain dry coil defrost energy, DFd, in W-h.

3.3.4.1.2 Operate the unit cooler at the frost load conditions as specified in appendix C, sections C11.1 and C11.1.1 to obtain frosted coil defrost energy, DFf, in W-h.

3.3.4.1.3 The number of defrosts per day, NDF, shall be calculated from the time interval between successive defrosts from the start of one defrost to the start of the next defrost at the frost load conditions.

3.3.4.1.4 Use appendix C, equations C13 and C14 in section C11.3 to calculate, respectively, the daily average defrost energy, DF, in W-h and the daily contribution of the load attributed to defrost QDF in Btu.

3.3.4.1.5 The defrost adequacy requirements in appendix C, section C11.3 shall apply.

3.3.4.2 If the frost load test is not performed:

3.3.4.2.1 Operate the unit cooler at the dry coil conditions as specified in appendix C, section C11.1 to obtain dry coil defrost energy, DFd, in W-h.

3.3.4.2.2 The frost load defrost energy, DFf, in W-h shall be equal to 1.05 multiplied by the dry coil energy consumption, DFd, measured using the dry coil condition test in appendix C, section C11.1.

3.3.4.2.3 The number of defrosts per day NDF used in subsequent calculations shall be 4.

3.3.4.2.4 Use appendix C, equation C13 in section C11.3 to calculate the daily average defrost energy, DF, in W-h.

3.3.4.2.5 The daily contribution of the load attributed to defrost QDF in Btu shall be calculated as follows:

3.3.5. If a unit has adaptive defrost, use appendix C, section C11.2 of AHRI 1250-2009 as follows:

3.3.5.1. When testing to certify to the energy conservation standards in § 431.306, do not perform the optional test for adaptive or demand defrost in appendix C, section C11.2.

3.3.5.2. When determining the represented value of the calculated benefit for the inclusion of adaptive defrost, conduct the optional test for adaptive or demand defrost in appendix C, section C11.2 to establish the maximum time interval allowed between dry coil defrosts. If this time is greater than 24 hours, set its value to 24 hours. Then, calculate NDF (the number of defrosts per day) by averaging the time in hours between successive defrosts for the dry coil condition with the time in hours between successive defrosts for the frosted coil condition, and dividing 24 by this average time. (The time between successive defrosts for the frosted coil condition is found as specified in section 3.3.4 of this appendix C of AHRI 1250-2009: That is, if the optional frosted coil test was performed, the time between successive defrosts for the frosted coil condition is found by performing the frosted coil test as specified in section 3.3.4.1 of this appendix; and if the optional frosted coil test was not performed, the time between successive defrosts for the frosted coil condition shall be set to 4 as specified in section 3.3.4.2. of this appendix) Use this new value of NDF in subsequent calculations.

3.3.6. For matched refrigeration systems and single-package dedicated systems, calculate the AWEF using the calculations in AHRI 1250-2009 (incorporated by reference; see § 431.303), section 7.4, 7.5, 7.6, or 7.7, as applicable.

3.3.7. Calculations for Unit Coolers Tested Alone.

3.3.7.1. Unit Coolers that are not High-Temperature Unit Coolers.

Calculate the AWEF and net capacity using the calculations in AHRI 1250-2009, section 7.9.

3.3.7.2 High-Temperature Unit Coolers.

Calculate AWEF on the basis that walk-in box load is equal to half of the system net capacity, without variation according to high and low load periods, and with EER set according to tested evaporator capacity, as follows:

The net capacity, q mix,evap, is determined from the test data for the unit cooler at the 38 °F suction dewpoint.

3.3.7.3. If the unit cooler has variable-speed evaporator fans that vary fan speed in response to load, then:

3.3.7.3.1. When testing to certify compliance with the energy conservation standards in § 431.306, fans shall operate at full speed during on-cycle operation. Do not conduct the calculations in AHRI 1250-2009, section 7.9.3. Instead, use AHRI 1250-2009, section 7.9.2 to determine the system's AWEF.

3.3.7.3.2. When calculating the benefit for the inclusion of variable-speed evaporator fans that modulate fan speed in response to load for the purpose of making representations of efficiency, use AHRI 1250-2009, section 7.9.3 to determine the system AWEF.

3.4.1. Refer to appendix C, section C.12 of AHRI 1250-2009 (incorporated by reference; see § 431.303), for the method of test for dedicated condensing units. The version of ASHRAE Standard 23 used for test methods, requirements, and procedures shall be ANSI/ASHRAE Standard 23.1-2010 (incorporated by reference; see § 431.303). When applying this test method, use the applicable test method modifications listed in sections 3.1 and 3.2 of this appendix. For the test conditions in AHRI 1250-2009, Tables 11, 12, 13, and 14, use the Suction A condition test points only.

3.4.2. Calculate the AWEF and net capacity for dedicated condensing units using the calculations in AHRI 1250-2009 (incorporated by reference; see § 431.303) section 7.8. Use the following modifications to the calculations in lieu of unit cooler test data:

3.4.2.1. For calculating enthalpy leaving the unit cooler to calculate gross capacity, (a) the saturated refrigerant temperature (dew point) at the unit cooler coil exit, Tevap, shall be 25 °F for medium-temperature systems (coolers) and −20 °F for low-temperature systems (freezers), and (b) the refrigerant temperature at the unit cooler exit shall be 35 °F for medium-temperature systems (coolers) and −14 °F for low-temperature systems (freezers). For calculating gross capacity, the measured enthalpy at the condensing unit exit shall be used as the enthalpy entering the unit cooler. The temperature measurement requirements of appendix C, section C3.1.6 of AHRI 1250-2009 and modified by section 3.2.1 of this appendix shall apply only to the condensing unit exit rather than to the unit cooler inlet and outlet, and they shall be applied for two measurements when using the DX Dual Instrumentation test method.

3.4.2.2. The on-cycle evaporator fan power in watts, EFcomp,on, shall be calculated as follows:

For medium-temperature systems (coolers), EFcomp,on = 0.013 × qmix,cd

For low-temperature systems (freezers), EFcomp,on = 0.016 × qmix,cd

3.4.2.3. The off-cycle evaporator fan power in watts, EFcomp,off, shall be calculated as follows:

EFcomp,off = 0.2 × EFcomp,on

3.4.2.4. The daily defrost energy use in watt-hours, DF, shall be calculated as follows:

For medium-temperature systems (coolers), DF = 0

For low-temperature systems (freezers), DF = 8.5 × 10−3 × qmix,cd 1.27 × NDF

3.4.2.5. The daily defrost heat load contribution in Btu, QDF, shall be calculated as follows:

For medium-temperature systems (coolers), QDF = 0

For low-temperature systems (freezers), QDF = 0.95 × DF × 3.412

For all hot gas defrost refrigeration systems, remove the hot gas defrost mechanical components and disconnect all such components from electrical power.

3.5.1 Hot Gas Defrost Dedicated Condensing Units Tested Alone: Test these units as described in section 3.4 of this appendix for electric defrost dedicated condensing units that are not matched for testing and are not single-package dedicated systems.

3.5.2 Hot Gas Defrost Matched Systems and Single-package Dedicated Systems: Test these units as described in section 3.3 of this appendix for electric defrost matched systems and single-package dedicated systems, but do not conduct defrost tests as described in sections 3.3.4 and 3.3.5 of this appendix. Calculate daily defrost energy use as described in section 3.4.2.4 of this appendix. Calculate daily defrost heat contribution as described in section 3.4.2.5 of this appendix.

3.5.3 Hot Gas Defrost Unit Coolers Tested Alone: Test these units as described in section 3.3 of this appendix for electric defrost unit coolers tested alone, but do not conduct defrost tests as described in sections 3.3.4 and 3.3.5 of this appendix. Calculate average defrost heat load Q DF, expressed in Btu/h, as follows:

DOE incorporated by reference in § 431.303, the entire standard for AHRI 1250-2020, ANSI/ASHRAE 16, ANSI/ASHRAE 23.1-2010, ANSI/ASHRAE 37, ANSI/ASHRAE 41.1, ANSI/ASHRAE 41.3, ANSI/ASHRAE 41.6, and ANSI/ASHRAE 41.10. However, certain enumerated provisions of these standards, as set forth in sections 0.1 through 0.8 of this appendix are inapplicable. To the extent there is a conflict between the terms or provisions of a referenced industry standard and the Cspan, the Cspan provisions control. To the extent there is a conflict between the terms or provisions of AHRI 1250-2020, ANSI/ASHRAE 16, ANSI/ASHRAE 23.1-2010, ANSI/ASHRAE 37, ANSI/ASHRAE 41.1, ANSI/ASHRAE 41.3, ANSI/ASHRAE 41.6, and ANSI/ASHRAE 41.10, the AHRI 1250-2020 provisions control.

This appendix covers the test requirements used to determine the net capacity and the AWEF2 of the refrigeration system of a walk-in cooler or walk-in freezer.

The definitions contained in § 431.302, AHRI 1250-2020, ANSI/ASHRAE 37, and ANSI/ASHRAE 16 apply to this appendix. When definitions in standards incorporated by reference are in conflict or when they conflict with this section, the hierarchy of precedence shall be in the following order: § 431.302, AHRI 1250-2020, and then either ANSI/ASHRAE 37 or ANSI/ASHRAE 16.

The term “unit cooler” used in AHRI 1250-2020 and this subpart shall be considered to address both “unit coolers” and “ducted fan coil units,” as appropriate.

2.2.1. Digital Compressor means a compressor that uses mechanical means for disengaging active compression on a cyclic basis to provide a reduced average refrigerant flow rate in response to a control system input signal.

2.2.2. Displacement Ratio, applicable to staged positive displacement compressor systems, means the swept volume rate, e.g. in cubic centimeters per second, of a given stage, divided by the swept volume rate at full capacity.

2.2.3. Duty Cycle, applicable to digital compressors, means the fraction of time that the compressor is engaged and actively compressing refrigerant.

2.2.4. Maximum Speed, applicable to variable-speed compressors, means the maximum speed at which the compressor will operate under the control of the dedicated condensing system control system for extended periods of time, i.e. not including short-duration boost-mode operation.

2.2.5. Minimum Speed, applicable to variable-speed compressors, means the minimum compressor speed at which the compressor will operate under the control of the dedicated condensing system control system.

2.2.6. Multiple-Capacity, applicable for describing a refrigeration system, indicates that it has three or more stages (levels) of capacity.

2.2.7. Speed Ratio, applicable to variable-speed compressors, means the ratio of operating speed to the maximum speed.

Determine the Annual Walk-in Energy Factor (AWEF2) and net capacity of walk-in cooler and walk-in freezer refrigeration systems by conducting the test procedure set forth in AHRI 1250-2020, with the modifications to that test procedure provided in this section. However, certain sections of AHRI 1250-2020, ANSI/ASHRAE 37, and ANSI/ASHRAE 16 are not applicable, as set forth in sections 0.1, 0.2, and 0.3 of this appendix. Round AWEF2 measurements to the nearest 0.01 Btu/Wh. Round net capacity measurements as indicated in table 1 of this appendix.

The following sections of this appendix provide additional instructions for testing. In cases where there is a conflict, the language of this appendix takes highest precedence, followed by AHRI 1250-2020, then ANSI/ASHRAE 37 or ANSI/ASHRAE 16. Any subsequent amendment to a referenced document by the standard-setting organization will not affect the test procedure in this appendix, unless and until the test procedure is amended by DOE. Material is incorporated as it exists on the date of the approval, and a notification of any change in the incorporation will be published in the Federal Register.

Use measuring instruments as described in section 4.1 of AHRI 1250-2020, with the following additional requirement.

3.1.1. Electrical Energy Input measured in Wh with a minimum accuracy of ±0.5% of reading (for Off-Cycle tests per footnote 5 of Table C3 in section C3.6.2 of AHRI 1250-2020).

Test conditions used to determine AWEF2 shall be as specified in Tables 4 through 17 of AHRI 1250-2020. Tables 7 and 11 of AHRI 1250-2020, labeled to apply to variable-speed outdoor matched-pair refrigeration systems, shall also be used for testing variable-capacity single-packaged outdoor refrigeration systems, and also for testing multiple-capacity matched-pair or single-packaged outdoor refrigeration systems. Test conditions used to determine AWEF2 for refrigeration systems not specifically identified in AHRI 1250-2020 are as enumerated in sections 3.5.1 through 3.5.6 of this appendix.

For fixed-capacity high-temperature matched-pair or single-packaged refrigeration systems with indoor condensing units, conduct tests using the test conditions specified in table 2 of this appendix. For fixed-capacity high-temperature matched-pair or single-packaged refrigeration systems with outdoor condensing units, conduct tests using the test conditions specified in table 3 of this appendix. For high-temperature unit coolers tested alone, conduct tests using the test conditions specified in table 4 of this appendix.

For medium-temperature CO2 Unit Coolers, conduct tests using the test conditions specified in table 5 of this appendix. For low-temperature CO2 Unit Coolers, conduct tests using the test conditions specified in table 6 of this appendix.

For two-capacity medium-temperature outdoor condensing units tested alone, conduct tests using the test conditions specified in table 7 of this appendix. For two-capacity medium-temperature indoor condensing units tested alone, conduct tests using the test conditions specified in table 8 of this appendix. For two-capacity low-temperature outdoor condensing units tested alone, conduct tests using the test conditions specified in table 9 of this appendix. For two-capacity low-temperature indoor condensing units tested alone, conduct tests using the test conditions specified in table 10 of this appendix.

For variable-capacity or multiple-capacity outdoor medium-temperature condensing units tested alone, conduct tests using the test conditions specified in table 11 of this appendix. For variable-capacity or multiple-capacity indoor medium-temperature condensing units tested alone, conduct tests using the test conditions specified in table 12 of this appendix. For variable-capacity or multiple-capacity outdoor low-temperature condensing units tested alone, conduct tests using the test conditions specified in table 13 of this appendix. For variable-capacity or multiple-capacity indoor low-temperature condensing units tested alone, conduct tests using the test conditions specified in table 14 of this appendix.

For variable- or multiple-capacity indoor medium-temperature matched-pair or single-packaged refrigeration systems, conduct tests using the test conditions specified in table 17 of this appendix. For variable- or multiple-capacity indoor low-temperature matched-pair or single-packaged refrigeration systems, conduct tests using the test conditions specified in table 18 of this appendix.

3.3.1 For medium- and low-temperature refrigeration systems with indoor condensing units, calculate walk-in box loads for high and low load periods as a function of net capacity as described in section 6.2.1 of AHRI 1250-2020.

3.3.2 For medium- and low-temperature refrigeration systems with outdoor condensing units, calculate walk-in box loads for high and low load periods as a function of net capacity and outdoor temperature as described in section 6.2.2 of AHRI 1250-2020.

3.3.3 For high-temperature refrigeration systems, calculate walk-in box load as follows.

Calculations used to determine AWEF2 based on performance data obtained for testing shall be as specified in section 7 of AHRI 1250-2020 with modifications as indicated in sections 3.4.7 through 3.4.10 of this appendix. Calculations used to determine AWEF2 for refrigeration systems not specifically identified in sections 7.1.1 through 7.1.6 of AHRI 1250-2020 are enumerated in sections 3.4.1 through 3.4.6 and 3.4.11 through 3.4.14 of this appendix.

3.4.1.1 Unit Cooler Power

Calculate maximum-capacity unit cooler power during the compressor on period E Fcomp,on, in Watts, using Equation 130 of AHRI 1250-2020 for medium-temperature refrigeration systems and using Equation 173 of AHRI 1250-2020 for low-temperature refrigeration systems.

Calculate unit cooler power during the compressor off period E Fcomp,off, in Watts, as 20 percent of the maximum-capacity unit cooler power during the compressor on period.

3.4.1.2 Defrost

For freezer refrigeration systems, calculate defrost heat contribution Q DF in Btu/h and the defrost average power consumption D F in W as a function of steady-state maximum gross refrigeration capacity Q grossk=2, as specified in section C10.2.2 of Appendix C of AHRI 1250-2020.

3.4.1.3 Net Capacity

Calculate steady-state maximum net capacity, q ssk=2, and minimum net capacity, q ssk=1 as follows:

3.4.1.4 Calculate average power input during the low load period as follows.

If the low load period box load, BL L, plus defrost heat contribution, Q DF (only applicable for freezers), is less than the minimum net capacity q ssk=1:

If the low load period box load, BL L, plus defrost heat contribution, Q DF, (only applicable for freezers) is greater than the minimum net capacity q ssk=1:

3.4.1.5 Calculate average power input during the high load period as follows.

3.4.1.6 Calculate the AWEF2 as follows:

3.4.2.1 Unit Cooler Power

Calculate maximum-capacity unit cooler power during the compressor on period E Fcomp,on as described in section 3.4.1.1 of this appendix.

Calculate unit cooler power during the compressor off period E Fcomp,off, in Watts, as 20 percent of the maximum-capacity unit cooler power during the compressor on period.

3.4.2.2 Defrost

Calculate Defrost parameters as described in section 4.4.1.2 of this appendix.

3.4.2.3 Net Capacity

Calculate steady-state maximum net capacity, q ssk=2, intermediate net capacity, q ssk=i, and minimum net capacity, q ssk=1 as follows:

Kf is the unit cooler power coefficient for intermediate capacity operation, set equal to 0.2 to represent low-speed fan operation if the Duty Cycle for a Digital Compressor, the Speed Ratio for a Variable-Speed Compressor, or the Displacement Ratio for a Multi-Stage Compressor at Intermediate Capacity is 65% or less, and otherwise set equal to 1.0.

3.4.2.4 Calculate average power input during the low load period as follows.

If the low load period box load, BL L, plus defrost heat contribution Q DF (only applicable for freezers) is less than the minimum net capacity q ssk=1:

Where E cu,off, in W, is the condensing unit off-mode power consumption, measured as described in section C3.5 of AHRI 1250-2020.

If the low load period box load BL L plus defrost heat contribution Q DF (only applicable for freezers) is greater than the minimum net capacity q ssk=1 and less than the intermediate net capacity q ssk=i:

3.4.2.5 Calculate average power input during the high load period as follows:

If the high load period box load, BL H, plus defrost heat contribution, Q DF (only applicable for freezers), is greater than the minimum net capacity q ssk=1 and less than the intermediate net capacity q ssk=i:

If the high load period box load, BL H, plus defrost heat contribution, Q DF (only applicable for freezers), is greater than the intermediate net capacity, q ssk=i, and less than the maximum net capacity, q ssk=2:

3.4.2.6 Calculate the AWEF2 as follows.

3.4.3.1 Unit Cooler Power

Calculate maximum-capacity unit cooler power during the compressor on period E Fcomp,on, in Watts, using Equation 153 of AHRI 1250-2020 for medium-temperature refrigeration systems and using Equation 196 of AHRI 1250-2020 for low-temperature refrigeration systems.

Calculate unit cooler power during the compressor off period E Fcomp,off, in Watts, as 20 percent of the maximum-capacity unit cooler power during the compressor on period.

3.4.3.2 Defrost

Calculate Defrost parameters as described in section 3.4.1.2 of this appendix.

3.4.3.3 Condensing Unit Off-Cycle Power

Calculate Condensing Unit Off-Cycle Power for temperature tj as follows.

3.4.3.4 Net Capacity and Condensing Unit Power Input

Calculate steady-state maximum net capacity, q ssk=2(tj), and minimum net capacity, q ssk=1(tj), and corresponding condensing unit power input levels E ssk=2(tj) and E ssk=1(tj) as a function of outdoor temperature tj as follows:

If tj ≤ 59 °F:

If 59 °F < tj:

3.4.3.5 Calculate average power input during the low load period as follows.

Calculate the temperature, tIL, in the following equation which the low load period box load, BL L(tj), plus defrost heat contribution, Q DF (only applicable for freezers), is less than the minimum net capacity, q ssk=1(tj), by solving the following equation for tIL:

For tj < tIL:

Where E cu,off(tj), in W, is the condensing unit off-mode power consumption for temperature tj, determined as indicated in section 3.4.3.3 of this appendix.

For tj ≥ tIL:

3.4.3.6 Calculate average power input during the high load period as follows.

Calculate the temperature, tIH, in the following equation which the high load period box load, BL H(tj), plus defrost heat contribution, Q DF (only applicable for freezers), is less than the minimum net capacity, q ssk=1(tj) , by solving the following equation for tIH:

Calculate the temperature, tIIH, in the following equation which the high load period box load BL H(tj) plus defrost heat contribution Q DF (only applicable for freezers) is less than the maximum net capacity q ssk=2(tj), by solving the following equation for tIIH:

For tj < tIH:

For tIH ≤ tj < tIIH:

For tIIH ≤ tj:

3.4.3.7 Calculate the AWEF2 as follows:

3.4.4.1 Unit Cooler Power

Calculate maximum-capacity unit cooler power during the compressor on period E Fcomp,on as described in section 3.4.1.1 of this appendix.

Calculate unit cooler power during the compressor off period E Fcomp,on, in Watts, as 20 percent of the maximum-capacity unit cooler power during the compressor on period.

3.4.4.2 Defrost

Calculate Defrost parameters as described in section 3.4.1.2 of this appendix.

3.4.4.3 Condensing Unit Off-Cycle Power

Calculate Condensing Unit Off-Cycle Power for temperature, tj, as described in section 3.4.3.3 of this appendix.

3.4.4.4 Net Capacity and Condensing Unit Power Input

Calculate steady-state maximum net capacity, q ssk=2(tj), intermediate net capacity, q ssk=i(tj) , and minimum net capacity, q ssk=1(tj), and corresponding condensing unit power input levels E ssk=2(tj), E ssk=i(tj), E ssk=1(tj) and as a function of outdoor temperature, tj, as follows:

If tj ≤ 59 °F:

If 59 °F < tj:

3.4.4.5 Calculate average power input during the low load period as follows.

Calculate the temperature, tIL, in the following equation which the low load period box load BL L(tj) plus defrost heat contribution, Q DF (only applicable for freezers), is less than the minimum net capacity, q ssk=1(tj), by solving the following equation for tIL:

Calculate the temperature, tVL, in the following equation which the low load period box load, BL L(tj), plus defrost heat contribution, Q DF (only applicable for freezers), is less than the intermediate net capacity, q ssk=i(tj), by solving the following equation for tVL:

For tj < tIL:

Where, E cu,off(tj) in W, is the condensing unit off-mode power consumption for temperature, tj, determined as indicated in section 3.4.3.3 of this appendix.

For tIL ≤ tj < tVL:

For tVL ≤ tj:

3.4.4.6 Calculate average power input during the high load period as follows.

Calculate the temperature tVH in the following equation which the high load period box load BL H(tj) plus defrost heat contribution Q DF (only applicable for freezers) is less than the intermediate net capacity q ssk=i(tj), by solving the following equation for tVH:

Calculate the temperature tIIH in the following equation which the high load period box load BL H(tj) plus defrost heat contribution Q DF (only applicable for freezers) is less than the maximum net capacity q ssk=2(tj), by solving the following equation for tIIH:

For tj < tVH:

For tVH ≤ tj < tIIH:

For tIIH ≤ tj:

3.4.4.7 Calculate the AWEF2 as follows:

3.4.5.1 Defrost

For freezer refrigeration systems, defrost heat contribution Q DF in Btu/h and the defrost average power consumption D F in W shall be as measured in accordance with section C10.2.1 of Appendix C of AHRI 1250-2020.

3.4.5.2 Calculate average power input during the low load period as follows.

If the low load period box load BL L plus defrost heat contribution Q DF (only applicable for freezers) is less than the minimum net capacity q ssk=1:

If the low load period box load BL L plus defrost heat contribution Q DF (only applicable for freezers) is greater than the minimum net capacity q ssk=1:

3.4.5.3 Calculate average power input during the high load period as follows.

3.4.5.4 Calculate the AWEF2 as follows:

3.4.6.1 Defrost

For freezer refrigeration systems, defrost heat contribution Q DF in Btu/h and the defrost average power consumption D F in W shall be as measured in accordance with section C10.2.1 of Appendix C of AHRI 1250-2020.

3.4.6.2 Calculate average power input during the low load period as follows.

If the low load period box load BL L plus defrost heat contribution Q DF (only applicable for freezers) is less than the minimum net capacity q ssk=1:

If the low load period box load BL L plus defrost heat contribution Q DF (only applicable for freezers) is greater than the minimum net capacity and less than the intermediate net capacity q ssk=i:

3.4.6.3 Calculate average power input during the high load period as follows.

If the high load period box load BL H plus defrost heat contribution Q DF (only applicable for freezers) is greater than the minimum net capacity q ssk=1 and less than the intermediate net capacity q ssk=i:

If the high load period box load BL H plus defrost heat contribution Q DF (only applicable for freezers) is greater than the intermediate net capacity q ssk=i and less than the maximum net capacity q ssk=2:

3.4.6.4 Calculate the AWEF2 as follows.

Calculate AWEF2 as described in section 7.6 of AHRI 1250-2020, with the following revisions.

3.4.7.1 Condensing Unit Off-Cycle Power

Calculate condensing unit off-cycle power for temperature tj as indicated in section 3.4.3.3 of this appendix. Replace the constant value E CU,off in Equations 55 and 70 of AHRI 1250-2020 with the values E CU,off(tj), which vary with outdoor temperature tj.

3.4.7.2 Unit Cooler Off-Cycle Power

Set unit cooler Off-Cycle power E Fcomp,off equal to the average of the unit cooler off-cycle power measurements made for test conditions A, B, and C.

3.4.7.3 Average Power During the Low Load Period

Calculate average power for intermediate-capacity compressor operation during the low load period E ss,Lk=v(tj) as described in section 7.6 of AHRI 1250-2020, except that, instead of calculating intermediate-capacity compressor EER using Equation 77 of AHRI 1250-2020, calculate EER as follows.

For tj < tVL:

For tVL ≤ tj:

3.4.7.4 Average Power During the High Load Period

Calculate average power for intermediate-capacity compressor operation during the high load period E ss,Hk=v(tj) as described in section 7.6 of AHRI 1250-2020, except that, instead of calculating intermediate-capacity compressor EER using Equation 61 of AHRI 1250-2020, calculate EER as follows:

For tj < tVH:

For tVH ≤ tj:

Calculate AWEF2 as described in section 7.5 of AHRI 1250-2020, with the following revisions for Condensing Unit Off-Cycle Power and Unit Cooler Off-Cycle Power. Calculate condensing unit off-cycle power for temperature tj as indicated in section 3.4.3.3 of this appendix. Replace the constant value E CU,off in Equations 13 and 29 of AHRI 1250-2020 with the values E CU,off(tj), which vary with outdoor temperature tj. Set unit cooler Off-Cycle power E Fcomp,off equal to the average of the unit cooler off-cycle power measurements made for test conditions A, B, and C.

Calculate AWEF2 as described in section 7.4 of AHRI 1250-2020, with the following revision for Condensing Unit Off-Cycle Power and Unit Cooler Off-cycle Power. Calculate condensing unit off-cycle power for temperature tj as indicated in section 3.4.3.3 of this appendix. Replace the constant value E CU,off in Equations 13 of AHRI 1250-2020 with the values E CU,off(tj), which vary with outdoor temperature tj. Set unit cooler Off-Cycle power E Fcomp,off equal to the average of the unit cooler off-cycle power measurements made for test conditions A, B, and C.

Calculate AWEF2 as described in section 7.9 of AHRI 1250-2020, with the following revision for Condensing Unit Off-Cycle Power. Calculate condensing unit off-cycle power for temperature tj as indicated in section 3.4.3.3 of this appendix rather than as indicated in Equations 157, 159, 202, and 204 of AHRI 1250-2020.

3.4.11.1 Calculate Load Factor LF as follows:

3.4.11.2 Calculate the AWEF2 as follows:

3.4.12.1 Calculate Load Factor LF(tj) for outdoor temperature tj as follows:

3.4.12.2 Calculate the AWEF2 as follows:

3.4.13.1 Calculate Refrigeration System Power Input as follows:

3.4.13.2 Calculate the load factor LF as follows:

3.4.13.3 Calculate AWEF2 as follows:

Calculate AWEF2 for CO2 Unit Coolers Tested Alone using the calculations specified in in section 7.8 of AHRI 1250-2020 for calculation of AWEF2 for Unit Cooler Tested Alone.

Test the Refrigeration System in accordance with AHRI 1250-2020 to determine refrigeration capacity and power input for the specified test conditions, with revisions and additions as described in this section.

In Appendix C, section C5.2.2 of AHRI 1250-2020, for applicable system configurations (matched pairs, single-packaged refrigeration systems, and standalone unit coolers), the unit under test may be used to aid in achieving the required test chamber conditions prior to beginning any steady state test. However, the unit under test must be inspected and confirmed to be free from frost before initiating steady state testing.

3.5.2.1 Refrigerant Temperature Measurements

When testing a condensing unit alone, measure refrigerant liquid temperature leaving the condensing unit, and the refrigerant vapor temperature entering the condensing unit as required in section C7.5.1.1.2 of Appendix C of AHRI 1250-2020 using the same measurement approach specified for the unit cooler in section C3.1.3 of Appendix C of AHRI 1250-2020. In all cases in which thermometer wells or immersed sheathed sensors are prescribed, if the refrigerant tube outer diameter is less than 1/2 inch, the refrigerant temperature may be measured using the average of two temperature measuring instruments with a minimum accuracy of ±0.5 °F placed on opposite sides of the refrigerant tube surface—resulting in a total of up to 8 temperature measurement devices used for the DX Dual Instrumentation method. In this case, the refrigerant tube shall be insulated with 1-inch thick insulation from a point 6 inches upstream of the measurement location to a point 6 inches downstream of the measurement location. Also, to comply with this requirement, the unit cooler/evaporator entering measurement location may be moved to a location 6 inches upstream of the expansion device and, when testing a condensing unit alone, the entering and leaving measurement locations may be moved to locations 6 inches from the respective service valves.

3.5.2.2 Mass Flow Meter Location

When using the DX Dual Instrumentation test method of AHRI 1250-2020, applicable for unit coolers, dedicated condensing units, and matched pairs, the second mass flow meter may be installed in the suction line as shown in Figure C1 of AHRI 1250-2020.

3.5.2.3 Subcooling at Refrigerant Mass Flow Meter

In section C3.4.5 of Appendix C of AHRI 1250-2020, when verifying subcooling at the mass flow meters, only the sight glass and a temperature sensor located on the tube surface under the insulation are required. Subcooling shall be verified to be within the 3 °F requirement downstream of flow meters located in the same chamber as a condensing unit under test and upstream of flow meters located in the same chamber as a unit cooler under test, rather than always downstream as indicated in AHRI 1250-2009, section C3.4.5. If the subcooling is less than 3 °F when testing a unit cooler, dedicated condensing unit, or matched pair (not a single-packaged system), cool the line between the condensing unit outlet and this location to achieve the required subcooling. When providing such cooling while testing a matched pair (a) set up the line-cooling system and also set up apparatus to heat the liquid line between the mass flow meters and the unit cooler, (b) when the system has achieved steady state without activation of the heating and cooling systems, measure the liquid temperature entering the expansion valve for a period of at least 30 minutes, (c) activate the cooling system to provide the required subcooling at the mass flow meters, (d) if necessary, apply heat such that the temperature entering the expansion valve is within 0.5 °F of the temperature measured during step (b), and (e) proceed with measurements once condition (d) has been verified.

3.5.2.4 Installation Instructions

Manufacturer installation instructions or installation instructions described in this section refer to the instructions that come packaged with or appear on the labels applied to the unit. This does not include online manuals.

Installation Instruction Hierarchy: If a given installation instruction provided on the label(s) applied to the unit conflicts with the installation instructions that are shipped with the unit, the label takes precedence. For testing of matched pairs, the installation instructions for the dedicated condensing unit shall take precedence. Setup shall be in accordance with the field installation instructions (laboratory installation instructions shall not be used). Achieving test conditions shall always take precedence over installation instructions.

3.5.2.5. Refrigerant Charging and Adjustment of Superheat and Subcooling.

All dedicated condensing systems (dedicated condensing units tested alone, matched pairs, and single packaged dedicated systems) that use flooding of the condenser for head pressure control during low-ambient-temperature conditions shall be charged, and superheat and/or subcooling shall be set, at Refrigeration C test conditions unless otherwise specified in the installation instructions.

If after being charged at Refrigeration C condition the unit under test does not operate at the Refrigeration A condition due to high pressure cut out, refrigerant shall be removed in increments of 4 ounces or 5 percent of the test unit's receiver capacity, whichever quantity is larger, until the unit operates at the Refrigeration A condition. All tests shall be run at this final refrigerant charge. If less than 0 °F of subcooling is measured for the refrigerant leaving the condensing unit when testing at B or C condition, calculate the refrigerant-enthalpy-based capacity (i.e., when using the DX dual instrumentation, the DX calibrated box, or single-packaged unit refrigerant enthalpy method) assuming that the refrigerant is at saturated liquid conditions at the condensing unit exit.

All dedicated condensing systems that do not use a flooded condenser design shall be charged at Refrigeration A test conditions unless otherwise specified in the installation instructions.

If the installation instructions give a specified range for superheat, sub-cooling, or refrigerant pressure, the average of the range shall be used as the refrigerant charging parameter target and the test condition tolerance shall be ±50 percent of the range. Perform charging of near-azeotropic and zeotropic refrigerants only with refrigerant in the liquid state. Once the correct refrigerant charge is determined, all tests shall run until completion without further modification.

3.5.2.5.1. When charging or adjusting superheat/subcooling, use all pertinent instructions contained in the installation instructions to achieve charging parameters within the tolerances. However, in the event of conflicting charging information between installation instructions, follow the installation instruction hierarchy listed in section 3.5.2.4. Conflicting information is defined as multiple conditions given for charge adjustment where all conditions specified cannot be met. In the event of conflicting information within the same set of charging instructions (e.g., the installation instructions shipped with the dedicated condensing unit), follow the hierarchy in Table 19 for priority. Unless the installation instructions specify a different charging tolerance, the tolerances identified in table 19 of this appendix shall be used.

3.5.2.5.2. Dedicated Condensing Unit.

If the Dedicated Condensing Unit includes a receiver and the subcooling target leaving the condensing unit provided in installation instructions cannot be met without fully filling the receiver, the subcooling target shall be ignored. Likewise, if the Dedicated Condensing unit does not include a receiver and the subcooling target leaving the condensing unit cannot be met without the unit cycling off on high pressure, the subcooling target can be ignored. Also, if no instructions for charging or for setting subcooling leaving the condensing unit are provided in the installation instructions, the refrigeration system shall be set up with a charge quantity and/or exit subcooling such that the unit operates during testing without shutdown (e.g., on a high-pressure switch) and operation of the unit is otherwise consistent with the requirements of the test procedure of this appendix and the installation instructions.

3.5.2.5.3. Unit Cooler. Use the shipped expansion device for testing. Otherwise, use the expansion device specified in the installation instructions. If the installation instructions specify multiple options for the expansion device, any specified expansion device may be used. The supplied expansion device shall be adjusted until either the superheat target is met, or the device reaches the end of its adjustable range. In the event the device reaches the end of its adjustable range and the super heat target is not met, test with the adjustment at the end of its range providing the closest match to the superheat target, and the test condition tolerance for super heat target shall be ignored. The measured superheat is not subject to a test operating tolerance. However, if the evaporator exit condition is used to determine capacity using the DX dual instrumentation method or the refrigerant enthalpy method, individual superheat value measurements may not be equal to or less than zero. If this occurs, or if the operating tolerances of measurements affected by expansion device fluctuation are exceeded, the expansion device shall be replaced, operated at an average superheat value higher than the target, or both, in order to avoid individual superheat value measurements less than zero and/or to meet the required operating tolerances.

3.5.2.5.4. Single-Packaged Unit. Unless otherwise directed by the installation instructions, install one or more refrigerant line pressure gauges during the setup of the unit, located depending on the parameters used to verify or set charge, as described in this section:

3.5.2.5.4.1. Install a pressure gauge in the liquid line if charging is on the basis of subcooling, or high side pressure or corresponding saturation or dew point temperature.

3.5.2.5.4.2. Install a pressure gauge in the suction line if charging is on the basis of superheat, or low side pressure or corresponding saturation or dew point temperature. Install this gauge as close to the evaporator as allowable by the installation instructions and the physical constraints of the unit. Use methods for installing pressure gauge(s) at the required location(s) as indicated in the installation instructions if specified.

3.5.2.5.4.3. If the installation instructions indicate that refrigerant line pressure gauges should not be installed and the unit fails to operate due to high-pressure or low-pressure compressor cut off, then a charging port shall be installed, and the unit shall be evacuated of refrigerant and charged to the nameplate charge.

3.5.2.6 Ducted Units

For systems with ducted evaporator air, or that can be installed with or without ducted evaporator air: Connect ductwork on both the inlet and outlet connections and determine external static pressure (ESP) as described in sections 6.4 and 6.5 of ANSI/ASHRAE 37. Use pressure measurement instrumentation as described in section 5.3.2 of ANSI/ASHRAE 37. Test at the fan speed specified in the installation instructions—if there is more than one fan speed setting and the installation instructions do not specify which speed to use, test at the highest speed. Conduct tests with the ESP equal to 50% of the maximum ESP allowed in the installation instructions, within a tolerance of −0.00/+0.05 inches of water column. If the installation instructions do not provide the maximum ESP, the ESP shall be set for testing such that the air volume rate is 2/3 of the air volume rate measured when the ESP is 0.00 inches of water column within a tolerance of −0.00/+0.05 inches of water column.

If testing using either the indoor or outdoor air enthalpy method to measure the air volume rate, adjust the airflow measurement apparatus fan to set the external static pressure—otherwise, set the external static pressure by symmetrically restricting the outlet of the test duct. In case of conflict, these requirements for setting airflow take precedence over airflow values specified in manufacturer installation instructions or product literature.

3.5.2.7. Two-Speed or Multiple-Speed Evaporator Fans. Two-Speed or Multiple-Speed evaporator fans shall be considered to meet the qualifying control requirements of section C4.2 of Appendix C of AHRI 1250-2020 for measuring off-cycle fan energy if they use a fan speed no less than 50% of the speed used in the maximum capacity tests.

3.5.2.8. Defrost

Use section C10.2.1 of Appendix C of AHRI 1250-2020 for defrost testing. The Test Room Conditioning Equipment requirement of section C10.2.1.1 of Appendix C of AHRI 1250-2020 does not apply.

3.5.2.8.1 Adaptive Defrost

When testing to certify compliance to the energy conservation standards, use NDF = 4, as instructed in section C10.2.1.7 or C10.2.2.1 of AHRI 1250-2020. When determining the represented value of the calculated benefit for the inclusion of adaptive defrost, use NDF = 2.5, as instructed in section C10.2.1.7 or C10.2.2.1 of AHRI 1250-2020.

3.5.2.8.2 Hot Gas Defrost

When testing to certify compliance to the energy conservation standards, remove the hot gas defrost mechanical components and disconnect all such components from electrical power. Test the units as if they are electric defrost units, but do not conduct the defrost tests described in section C10.2.1 of AHRI 1250-2020. Use the defrost heat and power consumption values as described in section C10.2.2 of AHRI 1250-2020 for the AWEF2 calculations.

3.5.2.9 Dedicated condensing units that are not matched for testing and are not single-packaged dedicated systems.

The temperature measurement requirements of sections C3.1.3 and C4.1.3.1 appendix C of AHRI 1250-2020 shall apply only to the condensing unit exit rather than to the unit cooler inlet and outlet, and they shall be applied for two measurements when using the DX Dual Instrumentation test method.

3.5.2.10. Single-packaged dedicated systems

Use the test method in section C9 of appendix C of AHRI 1250-2020 (including the applicable provisions of ASHRAE 16-2016, ASHRAE 23.1-2010, ASHRAE 37-2009, and ASHRAE 41.6-2014, as referenced in section C9.1 of AHRI 1250-2020) as the method of test for single-packaged dedicated systems, with modifications as described in this section. Use two test methods listed in table 20 of this appendix to calculate the net capacity and power consumption. The test method listed with a lower “Hierarchy Number” and that has “Primary” as an allowable use in table 20 of this appendix shall be considered the primary measurement and used as the net capacity.

3.5.2.10.1 Single-Packaged Refrigerant Enthalpy Method

The single-packaged refrigerant enthalpy method shall follow the test procedure of the DX Calibrated Box method in AHRI 1250-2020, appendix C, section C8 for refrigerant-side measurements with the following modifications:

3.5.2.10.1.1 Air-side measurements shall follow the requirements of the primary single-packaged method listed in table 20 of this appendix. The air-side measurements and refrigerant-side measurements shall be collected over the same intervals.

3.5.2.10.1.2 A preliminary test at Test Rating Condition A is required using the primary method prior to any modification necessary to install the refrigerant-side measuring instruments. Install surface mount temperature sensors on the evaporator and condenser coils at locations not affected by liquid subcooling or vapor superheat (i.e., near the midpoint of the coil at a return bend), entering and leaving the compressor, and entering the expansion device. These temperature sensors shall be included in the regularly recorded data.

3.5.2.10.1.3 After the preliminary test is completed, the refrigerant shall be removed from the equipment and the refrigerant-side measuring instruments shall be installed. The equipment shall then be evacuated and recharged with refrigerant. Once the equipment is operating at Test Condition A, the refrigerant charge shall be adjusted until, as compared to the average values from the preliminary test, the following conditions are achieved:

(a) Each on-coil temperature sensor indicates a reading that is within ±1.0 °F of the measurement in the initial test,

(b) The temperatures of the refrigerant entering and leaving the compressor are within ±4 °F, and

(c) The refrigerant temperature entering the expansion device is within ±1 °F.

3.5.2.10.1.4 Once these conditions have been achieved over an interval of at least 10 minutes, refrigerant charging equipment shall be removed and the official tests shall be conducted.

3.5.2.10.1.5 The lengths of liquid line to be added shall be 5 feet maximum, not including the requisite flow meter. This maximum length applies to each circuit separately.

3.5.2.10.1.6 Use section C9.2 of appendix C of AHRI 1250-2020 for allowable refrigeration capacity heat balance. Calculate the single-packaged refrigerant enthalpy (secondary) method test net capacity

UAcond and UAamb are, for the condenser/evaporator partition and the evaporator compartment walls exposed to ambient air, respectively, the product of the overall heat transfer coefficient and surface area of the unit as manufactured, i.e. without external insulation that might have been added during the test. The areas shall be calculated based on measurements, and the thermal resistance values shall be based on insulation thickness and insulation material;

Tevapside is the air temperature in the evaporator compartment—the measured evaporator air inlet temperature may be used;

Tcondside is the air temperature in the condenser compartment—the measured chamber ambient temperature may be used, or a measurement may be made using a temperature sensor placed inside the condenser box at least 6 inches distant from any part of the refrigeration system; and

Tamb is the air temperature outside the single-packaged system.

3.5.2.10.1.7 For multi-circuit single-packaged systems utilizing the single-packaged refrigerant enthalpy method, apply the test method separately for each circuit and sum the separately-calculated refrigerant-side gross refrigeration capacities.

3.5.2.10.2 Calibrated Box Test Procedure

3.5.2.10.2.1 Measurements. Refer to section C3 of AHRI 1250-2020 (including the applicable provisions of ASHRAE 41.1-2013, ASHRAE 41.3-2014, and ASHRAE 41.10-2013, as referenced in section C3 of AHRI 1250-2020) for requirements of air-side and refrigerant-side measurements.

3.5.2.10.2.2 Apparatus setup for Calibrated Box Calibration and Test. Refer to section C5 of AHRI 1250-2020 and section C8 of AHRI 1250-2020 for specific test setup.

3.5.2.10.2.3 The calibrated box shall be installed in a temperature-controlled enclosure in which the temperature can be maintained at a constant level. When using the calibrated box method for Single-Packaged Dedicated Systems, the enclosure air temperature shall be maintained such that the condenser air entering conditions are as specified for the test.

3.5.2.10.2. The temperature-controlled enclosure shall be of a size that will provide clearances of not less than 18 in at all sides, top and bottom, except that clearance of any one surface may be reduced to not less than 5.5 inches.

3.5.2.10.2.5 The heat leakage of the calibrated box shall be noted in the test report.

3.5.2.10.2.6 Refrigerant lines within the calibrated box shall be well insulated to avoid appreciable heat loss or gain.

3.5.2.10.2.7 Instruments for measuring the temperature around the outside of the calibrated box to represent the enclosure temperature Ten shall be located at the center of each wall, ceiling, and floor. Exception: in the case where a clearance around the outside of the calibrated box, as indicated in section 3.5.2.10.2.4 of this appendix, is reduced to less than 18 inches, the number of temperature measuring devices on the outside of that surface shall be increased to six, which shall be treated as a single temperature to be averaged with the temperature of each of the other five surfaces. The six temperature measuring instruments shall be located at the center of six rectangular sections of equal area. If the refrigeration system is mounted at the location that would cover the center of the face on which it is mounted, up to four temperature measurements shall be used on that face to represent its temperature. Each sensor shall be aligned with the center of the face's nearest outer edge and centered on the distance between that edge and the single-packaged unit (this is illustrated in figure C5 of this section when using surface temperature sensors), and they shall be treated as a single temperature to be averaged with the temperature of each of the other five surfaces. However, any of these sensors shall be omitted if either (a) the distance between the outer edge and the single-packaged unit is less than one foot or (b) if the sensor location would be within two feet of any of the foot square surfaces discussed in section 3.5.2.10.2.8 of this appendix representing a warm discharge air impingement area. In this case, the remaining sensors shall be used to represent the average temperature for the surface.

3.5.2.10.2.8 One of the following two approaches shall be used for the box external temperature measurement. Box calibration and system capacity measurement shall both be done using the same one of these approaches. 1: Air temperature sensors. Each temperature sensor shall be at a distance of 6 inches from the calibrated box. If the clearance from a surface of the box (allowed for one surface only) is less than 12 inches, the temperature measuring instruments shall be located midway between the outer wall of the calibrated box and the adjacent surface. 2: Surface temperature sensors. Surface temperature sensors shall be mounted on the calibrated box surfaces to represent the enclosure temperature, Ten.

3.5.2.10.2.9 Additional surface temperature sensors may be used to measure external hot spots during refrigeration system testing. If this is done, two temperature sensors shall be used to measure the average temperature of the calibrated box surface covered by the condensing section—they shall be located centered on equal-area rectangles comprising the covered calibrated box surface whose common sides span the short dimension of this surface. Additional surface temperature sensors may be used to measure box surfaces on which warm condenser discharge air impinges. A pattern of square surfaces measuring one foot square shall be mapped out to represent the hot spot upon which the warm condenser air impinges. One temperature sensor shall be used to measure surface temperature at the center of each square (see figure C5 of this section). A drawing showing this pattern and identifying the surface temperature sensors shall be provided in the test report. The average surface temperature of the overall calibrated box outer surface during testing shall be calculated as follows.

3.5.2.10.2.11 The average air dry-bulb temperature in the calibrated box during Single-Packaged Dedicated System tests and calibrated box heat leakage tests shall be the average of eight temperatures measured at the corners of the box at a distance of 2 inches to 4 inches from the walls. The instruments shall be shielded from any cold or warm surfaces except that they shall not be shielded from the adjacent walls of the box. The Single-Packaged Dedicated System under test shall be mounted such that the temperature instruments are not in the direct air stream from the discharge of the Single-Packaged Dedicated System.

3.5.2.10.2.12 Calibration of the Calibrated Box. Calibration of the Calibrated Box shall occur prior to installation of the Single-Packaged Dedicated System. This shall be done either (a) prior to cutting the opening needed to install the Single-Packaged Dedicated System, or (b) with an insulating panel with the same thickness and thermal resistance as the box wall installed in the opening intended for the Single-Packaged Dedicated System installation. Care shall be taken to avoid thermal shorts in the location of the opening either during calibration or during subsequent installation of the Single-Packaged Dedicated System. A calibration test shall be made for air movements comparable to those expected for Single-Packaged Dedicated System capacity measurement, i.e., with air volume flow rate within 10 percent of the air volume flow rate of the Single-Packaged Dedicated System evaporator.

3.5.2.10.2.13 The heat input shall be adjusted to maintain an average box temperature not less than 25.0 °F above the test enclosure temperature.

3.5.2.10.2.14 The average dry-bulb temperature inside the calibrated box shall not vary more than 1.0 °F over the course of the calibration test.

3.5.2.10.2.15 A calibration test shall be the average of 11 consecutive hourly readings when the box has reached a steady-state temperature condition.

3.5.2.10.2.16 The box temperature shall be the average of all readings after a steady-state temperature condition has been reached.

3.5.2.10.2.17 The calibrated box has reached a steady-state temperature condition when: The average box temperature is not less than 25 °F above the test enclosure temperature. Temperature variations do not exceed 5.0 °F between temperature measuring stations. Temperatures do not vary by more than 2 °F at any one temperature- measuring station.

3.5.2.10.2.18 Data to be Measured and Recorded. Refer to Table C5 in section C6.2 of AHRI 1250-2020 for the required data that need to measured and recorded.

3.5.2.10.2.19 Refrigeration Capacity Calculation.

The heat leakage coefficient of the calibrated box is calculated by

For each Dry Rating Condition, calculate the Net Capacity:

3.5.2.10.3 Detachable single-packaged systems shall be tested as single-packaged dedicated refrigeration systems.

3.5.2.11 Variable-Capacity and Multiple-Capacity Dedicated Condensing Refrigeration Systems

3.5.2.11.1 Manufacturer-Provided Equipment Overrides

Where needed, the manufacturer must provide a means for overriding the controls of the test unit so that the compressor(s) operates at the specified speed or capacity and the indoor blower operates at the speed consistent with the compressor operating level as would occur without override.

3.5.2.11.2 Compressor Operating Levels

For variable-capacity and multiple-capacity compressor systems, the minimum capacity for testing shall be the minimum capacity that the system control would operate the compressor in normal operation. Likewise, the maximum capacity for testing shall be the maximum capacity that the system control would operate the compressor in normal operation. For variable-speed compressor systems, the intermediate speed for testing shall be the average of the minimum and maximum speeds. For digital compressor systems, the intermediate duty cycle shall be the average of the minimum and maximum duty cycles. For multiple-capacity compressor systems with three capacity levels, the intermediate operating level for testing shall be the middle capacity level. For multiple-capacity compressor systems with more than three capacity levels, the intermediate operating level for testing shall be the level whose displacement ratio is closest to the average of the maximum and minimum displacement ratios.

3.5.2.11.3 Refrigeration Systems with Digital Compressor(s)

Use the test methods described in section 3.5.2.10.1 of this appendix as the secondary method of test for refrigeration systems with digital compressor(s) with modifications as described in this section. The Test Operating tolerance for refrigerant mass flow rate and suction pressure in Table 2 of AHRI 1250-2020 shall be ignored. Temperature and pressure measurements used to calculate shall be recorded at a frequency of once per second or faster and based on average values measured over the 30-minute test period.

3.5.2.11.3.1 For Matched pair (not including single-packaged systems) and Dedicated Condensing Unit refrigeration systems, the preliminary test in sections 3.5.2.10.1.2 and 3.5.2.10.1.3 of this appendix is not required. The liquid line and suction line shall be 25 feet ± 3 inches, not including the requisite flow meters. Also, the term in the equation to calculate net capacity shall be set equal to zero.

3.5.2.11.3.2 For Dedicated Condensing Unit refrigeration systems, the primary capacity measurement method shall be balanced ambient outdoor calorimeter, outdoor air enthalpy, or outdoor room calorimeter.