The purpose of this procedure is to verify that residential split system air conditioners and heat pumps have the required refrigerant charge and that the metering device is working as designed. The procedures only apply to ducted split system central air-cooled air conditioners and ducted split system central air-source heat pumps for which the system manufacturer has specified that this procedure may be used to verify refrigerant charge.
The Standard Charge Verification Procedure (Section RA3.2.2 of the Reference Residential Appendices) calls for the outdoor temperature to be within the manufacturer's specified range. When outdoor temperatures are below 55°F, the setup for the Standard Charge Verification Procedure must be modified in order to achieve the proper system pressure differential needed for the procedure. The Winter Setup for the Standard Charge Verification Procedure (Winter Charge Setup) allows both installers and HERS Raters to utilize the Standard Charge Verification Procedure of Section RA3.2.2 in the winter. Note that the Weigh-in Charging Procedure specified in Section RA3.2.3 may also be used only by the installer.
The Winter Charge Setup creates the right conditions at the unit being tested for outdoor temperatures above 37°F and below 71°F that allow the system to operate in the same range of pressure differences between the low side pressure and the high side pressure as occurs during warm outdoor temperatures.
The Winter Charge Setup is used only for units equipped with variable metering devices, which include Thermostatic Expansion Valves (TXV) and Electronic Expansion Valves (EXV) for which the manufacturer specifies subcooling as the means for determining the proper charge for the unit, including units equipped with micro-channel heat exchangers. The Winter Charge Setup achieves an appropriate high side - low side pressure differential to conduct the Standard Charge Verification Procedure, by restricting the airflow at the condenser fan outlet through the use of a Condenser Outlet Air Restrictor. Once this pressure differential is achieved, the Variable Metering Device Calculations are conducted in the same way as the variable metering device procedures described in Reference Residential Appendix RA3.2.2.6.2. All other applicable requirements of Section RA3.2.2 remain the same and must also be completed when using the Winter Charge Setup.
Definition - Condenser Outlet Air Restrictor: A device which restricts the free area of the outlet from the condenser fan to reduce the air flow, but does not interfere with air entering the condenser coil. The amount of restriction shall be adjustable to allow the operator to vary the airflow to achieve the target refrigerant pressure difference.
- (a) Install the condenser outlet air restrictor on the outlet from the condenser fan:
- Position the restrictor so it does not interfere with the inlet airflow to the condenser.
- Start the air conditioner or heat pump in the cooling mode and restrict the outlet until the difference between the high side pressure and the low side pressure is between 160 psi and 220 psi for R-410A refrigerant and 100 to 145 psi for R-22 refrigerant.
- 160 psi ≤ (Phigh, – Plow ) ≤ 220 psi for R-410A refrigerant;
- 100 psi ≤ (Phigh, – Plow ) ≤ 145 psi for R-22 refrigerant
- Allow the unit to stabilize for 15 minutes, watching the pressures to make sure the differential achieves and remains within
- 160 psi ≤ (Phigh, – Plow ) ≤ 220 psi for R-410A refrigerant
- 100 psi ≤ (Phigh, – Plow ) ≤ 145 psi for R-22 refrigerant
- (b) Follow the test procedures specified in the Reference Residential Appendix, Section RA3.2.2.6.2, Variable Metering Device Calculations to determine compliance.
The Winter Charge Setup may only be used for equipment for which the air conditioning manufacturer approves the use of the Winter Charge Setup. Refer to the Energy Commissions website for the list of split system air conditioner units approved by the manufacturers to use the Winter Charge Setup. In addition to the requirements of Section RA1.2, manufacturers may issue additional instructions/clarification for the equipment and procedures required to be used to conduct the Winter Charge Setup. These additional instruction/clarifications shall also be available on the Energy Commission website: www.energy.ca.gov/title24/.
Winter Charge Setup may be used for systems that use a target subcooling for refrigerant charge verification, including units equipped with micro-channel heat exchangers where the manufacturer specifies subcooling for measuring refrigerant charge.
Similar to the Standard Charge Verification Procedure for warm weather, the Winter Charge Setup may be used by the Installer and/or the HERS Rater.
The system shall comply with the minimum system airflow requirements specified in Reference Residential Appendix Section RA3.3.3.1.
Similar to the Standard Charge Verification Procedure for warm weather, the Winter Charge Setup requires that the return air dry bulb temperature must be maintained within the manufacturer's specification during the test, as specified in RA3.2.2. Suggestions for methods to accomplish warmer return air are posted on the Energy Commission website at the following link:
http://www.energy.ca.gov/title24/orc/hvac/ Similar to the Standard Charge Measurement Procedure for warm weather, the Winter Charge Setup procedure does not relieve the installing contractor from any obligations to follow manufacturers’ specifications. The procedures in Section RA1.2 are used to demonstrate compliance with Title 24, Part 6 requirements for refrigerant charge verification.