10 C.F.R. § R app C to Subpart R of Part 431
Note: Prior to October 31, 2023, representations with respect to the energy use of refrigeration components of walk-in coolers and walk-in freezers, including compliance certifications, must be based on testing conducted in accordance with the applicable provisions of 10 CFR part 431 , subpart R, appendix C, revised as of January 1, 2022. Beginning October 31, 2023, representations with respect to energy use of refrigeration components of walk-in coolers and walk-in freezers, including compliance certifications, must be based on testing conducted in accordance with this appendix. For any amended standards for walk-in coolers and freezers published after January 1, 2022, manufacturers must use the results of testing under appendix C1 to this subpart to determine compliance. Representations related to energy consumption must be made in accordance with appendix C1 when determining compliance with the relevant standard. Manufacturers may also use appendix C1 to certify compliance with any amended standards prior to the applicable compliance date for those standards.
1.0 Scope
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.
2.0 Definitions
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.
3.0 Test Methods, Measurements, and Calculations
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:
Table 15-Refrigerator Unit Cooler
| Test description | Unit cooler air entering dry-bulb, °F | Unit cooler air entering relative humidity, % | Saturated suction temp, °F | Liquid inlet saturation temp, °F | Liquid inlet subcooling temp, °F | Compressor capacity | Test objective |
| Off Cycle Fan Power | 35 | [LESS THAN]50 | - | - | - | Compressor Off | Measure fan input power during compressor off cycle. |
| Refrigeration Capacity Suction A | 35 | [LESS THAN]50 | 25 | 105 | 9 | Compressor On | Determine Net Refrigeration Capacity of Unit Cooler. |
| Refrigeration Capacity Suction B | 35 | [LESS THAN]50 | 20 | 105 | 9 | Compressor On | Determine Net Refrigeration Capacity of Unit Cooler. |
Note: Superheat to be set according to equipment specification in equipment or installation manual. If no superheat specification is given, a default superheat value of 6.5 °F shall be used. The superheat setting used in the test shall be reported as part of the standard rating.
Table 16-Freezer Unit Cooler
| Test description | Unit cooler air entering dry-bulb, °F | Unit cooler air entering relative humidity, % | Saturated suction temp, °F | Liquid inlet saturation temp, °F | Liquid inlet subcooling temp, °F | Compressor capacity | Test objective |
| Off Cycle Fan Power | -10 | [LESS THAN]50 | - | - | - | Compressor Off | Measure fan input power during compressor off cycle. |
| Refrigeration Capacity Suction A | -10 | [LESS THAN]50 | -20 | 105 | 9 | Compressor On | Determine Net Refrigeration Capacity of Unit Cooler. |
| Refrigeration Capacity Suction B | -10 | [LESS THAN]50 | -26 | 105 | 9 | Compressor On | Determine Net Refrigeration Capacity of Unit Cooler. |
| Defrost | -10 | Various | - | - | - | Compressor Off | Test according to Appendix C Section C11. |
Note: Superheat to be set according to equipment specification in equipment or installation manual. If no superheat specification is given, a default superheat value of 6.5 °F shall be used. The superheat setting used in the test shall be reported as part of the standard rating.
3.1.6. Test Operating Conditions for CO2 Unit Coolers
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.
Table C.1-Test Operating Conditions for Medium-Temperature CO2 Unit Coolers
| Test description | Unit cooler air entering dry-bulb, °F | Unit cooler air entering relative humidity, % | Suction dew point temp, °F | Liquid inlet bubble point temperature °F | Liquid inlet subcooling, °F | Compressor capacity | Test objective |
| Off-Cycle Power | 35 | [LESS THAN]50 | Compressor Off | Measure fan input power during compressor off-cycle. | |||
| Refrigeration Capacity, Ambient Condition A | 35 | [LESS THAN]50 | 25 | 38 | 5 | Compressor On | Determine Net Refrigeration Capacity of Unit Cooler. |
Notes:
1 Superheat shall be set as indicated in the installation instructions. If no superheat specification is given a default superheat value of 6.5 °F shall be used.
Table C.2-Test Operating Conditions for Low-Temperature CO2 Unit Coolers
| Test description | Unit cooler air entering dry-bulb, °F | Unit cooler air entering relative humidity, % | Suction dew point temp, °F | Liquid inlet bubble point temperature °F | Liquid inlet subcooling, °F | Compressor capacity | Test objective |
| Off-Cycle Power | -10 | [LESS THAN]50 | Compressor Off | Measure fan input power during compressor off cycle. | |||
| Refrigeration Capacity, Ambient Condition A | -10 | [LESS THAN]50 | -20 | 38 | 5 | Compressor On | Determine Net Refrigeration Capacity of Unit Cooler. |
| Defrost | -10 | [LESS THAN]50 | Compressor Off | Test according to Appendix C Section C11 of AHRI 1250-2009. |
1. Superheat shall be set as indicated in the installation instructions. If no superheat specification is given a default superheat value of 6.5 °F shall be used.
3.1.7. Test Operating Conditions for High-Temperature Unit Coolers
For high-temperature cooler unit coolers, conduct tests using the test conditions specified in table C.3 of this appendix.
Table C.3-Test Operating Conditions for High-Temperature Unit Coolers
| Test description | Unit cooler air entering dry-bulb, °F | Unit cooler air entering relative humidity, %1 | Suction dew point temp, °F23 | Liquid inlet bubble point temperature °F | Liquid inlet subcooling, °F | Compressor capacity | Test objective |
| Off-Cycle | 55 | 55 | 105 | 9 | Compressor Off | Measure fan input power. | |
| Refrigeration Capacity Suction A | 55 | 55 | 38 | 105 | 9 | Compressor On | Determine Net Refrigeration Capacity of Unit Cooler. |
Notes:
1 The test condition tolerance (maximum permissible variation of the average value of the measurement from the specified test condition) for relative humidity is 3%.
2 Superheat shall be set as indicated in the installation instructions. If no superheat specification is given a default superheat value of 6.5 °F shall be used.
3 Suction Dew Point shall be measured at the Unit Cooler Exit.
3.2. General Modifications: Methods of Testing
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 0.50F 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 ft2- °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.
Table 1-Test Condition Tolerances and Hierarchy for Refrigerant Charging and Setting of Refrigerant Conditions
| Priority | Fixed orifice | Expansion valve | ||
| Parameter with installation instruction target | Tolerance | Parameter with installation instruction target | Tolerance | |
| 1 | Superheat | ±2.0 °F | Subcooling | 10% of the Target Value; No less than ±0.5 °F, No more than ±2.0 °F. |
| 2 | High Side Pressure or Saturation Temperature | ±4.0 psi or ±1.0 °F | High Side Pressure or Saturation Temperature | ±4.0 psi or ±1.0 °F. |
| 3 | Low Side Pressure or Saturation Temperature | ±2.0 psi or ±0.8 °F | Superheat | ±2.0 °F. |
| 4 | Low Side Temperature | ±2.0 °F | Low Side Pressure or Saturation Temperature | ±2.0 psi or ±0.8 °F. |
| 5 | High Side Temperature | ±2.0 °F | Approach Temperature | ±1.0 °F. |
| 6 | Charge Weight | ±2.0 oz | Charge Weight | 0.5% or 1.0 oz, whichever is greater. |
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.
EFcomp,on Total electrical power input to fan motor(s) of Unit Cooler, W
FS Fan speed(s), rpm
N Number of motors
Pb Barometric pressure, in. Hg
Tdb Dry-bulb temperature of air at inlet, °F
Twb Wet-bulb temperature of air at inlet, °F
V Voltage of each phase
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.
= 0.1 * EFcomp,on
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:
Where:
DFd = the defrost energy, in W-h, measured at the dry coil condition
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, qmix,evap, is determined from the test data for the unit cooler at the 38 °F suction dewpoint.
Where:
Where:
BL is the non-equipment-related box load;
LF is the load factor; and
Other symbols are as defined in section 8 of AHRI 1250-2009.
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. Dedicated condensing units that are not matched for testing and are not single-package dedicated systems
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
Where:
qmix,cd is the gross cooling capacity of the system in Btu/h, found by a single test at the Capacity A, Suction A condition for outdoor units and the Suction A condition for indoor units.
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
Where:
EFcomp,on is the on-cycle evaporator fan power in watts.
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,cd1.27 * NDF
Where:
qmix,cd is the gross cooling capacity of the system in Btu/h, found by a single test at the Capacity A, Suction A condition for outdoor units and the Suction A condition for indoor units, and
NDF is the number of defrosts per day, equal to 4.
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
Where:
DF is the daily defrost energy use in watt-hours.
3.5 Hot Gas Defrost Refrigeration Systems
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 QDF, expressed in Btu/h, as follows:
10 C.F.R. § R app C to Subpart R of Part 431