Code Cycle: 2016 & 2019 Standards
Reference: See footnotes and code references below
Reference: CalCERTS Alterations training Manual Chapter 9, Section 6
Weigh-In Charging Procedures For Air-Cooled Air Conditioners And Air-Source Heat Pumps, Including But Not Limited To Ducted Split Systems, Ducted Package Systems, And Mini-Split Systems.
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Applicable in Climate Zones 2 and 8-15
For systems of a type that CAN utilize the standard charging verification4
When the outdoor temperature is 55°F or higher:
- The installer may choose to perform the evacuation and Weigh-in Charge Verification Method2, regardless of the weather/temperatures; AND
- The HERS rater shall verify the charge using the standard charge verification1 procedure utilizing superheat/subcool.
When the outdoor temperature is less than 55 degrees, there are two options3:
The installer shall:
- Perform the weigh-in charging procedure2; AND
- Install an Occupant Controlled Smart Thermostat (OCST)4.
The HERS Rater shall:
- Observe the evacuation and weigh-in2, and confirm the correction calculations; AND
- Complete the CF3R documentation to close out the project.
The installer shall:
- Perform the evacuation and weigh-in charging procedure2; AND
- Include the homeowner’s and HERS rater’s signatures on the CF2R-MCH-25c form3; AND
- Provide written notice to the homeowner that the charge has not been verified3; AND
The HERS rater shall:
- Return at a later date when the weather is warmer; AND
- Use the standard charging method of verification; AND
- Complete the CF3R documentation to close out the project upon obtaining passing results.
For systems of a type that CANNOT utilize the standard charging method (superheat/subcool), such as mini-splits6
- The installer shall perform the evacuation and Weigh-in Charge Verification Method2; AND
- The HERS rater shall observe the evacuation and weigh-in2, and confirm the correction calculations; AND
- The HERS rater shall complete the CF3R documentation to close out the project.
Foot Notes and References:
- Standard Charging Verification Procedure: Reference Appendices RA3.2.2.
- Weigh-in Charging Procedure: Reference Appendices RA22.214.171.124.5 for installers; RA126.96.36.199 for the HERS Rater Observation; Enforcement Agency RA2.4.4
- Weigh-in Charging Procedure at Low Temperatures: Standards Exception 1 to §150.1(c)7AicIII; Exception to §150.2(b)1Fiib; Res Compliance Manual RCM188.8.131.52
- OCST: Reference Appendix JA5
- Sample groups are prohibited when the weigh-in method is used: RCM 184.108.40.206; RA220.127.116.11(d)
- Equipment Limitations/Mini-splits: RCM 18.104.22.168
- Weigh-in charging procedure is an acceptable method at any outdoor temperature: RA3.2.3
RA22.214.171.124.5 Weigh-in Procedure
The weigh-in procedure shall be performed in accordance with all manufacturer specifications to confirm:
(a) Liquid line filter drier has been installed if required per outdoor condensing unit manufacturer's instructions, and installed with the proper orientation with respect to refrigerant flow, if applicable.
(b) The system is braised with dry nitrogen in the lines and indoor coil.
(c) The system is evacuated to 500 microns or less and, when isolated, rises no more than 300microns over five minutes.
(d) The lineset correction is calculated based on the length and diameter of the lineset.
(e) The indoor coil correction to refrigerant weight is used if it is supplied by the manufacturer.
(f) The amount of charge calculated for the lineset correction (and indoor coil correction if available) is added or removed, or the total charge based on the lineset, indoor coil, and standard label charge is installed.
The HVAC Installer shall certify on the Certificate of Installation that the manufacturer's specifications for these procedures have been met.
RA126.96.36.199 - HERS Rater - Observation of Weigh-In Charging Procedure
When the Standards indicate this procedure is required, or is an option for compliance, the HERS Rater shall coordinate with the HVAC Installer to observe the weigh-in charging procedure.
HERS Rater shall observe and confirm:
(a) The system is evacuated to 500 microns or less and, when isolated, rises no more than 300 microns over five minutes.
(b) The lineset correction is calculated based on the length and diameter of the lineset, including the liquid line filter drier if required per outdoor condensing unit manufacturer instructions.
(c) The indoor coil correction to refrigerant weight is used if it is supplied by the manufacturer.
(d) The installer adds or removes the amount of charge calculated for the lineset correction or installs the total charge based on lineset, indoor coil, and standard label charge.
Minimum System Airflow
Systems that utilize forced air ducts shall comply with the minimum system airflow rate requirement in Section 150.2(b)1Fiia provided the system is of a type that can be verified using the procedures in RA3.3 or an approved alternative procedure in RA1.