Specifications

2008 Residential Appendices RA3-13
Appendix RA3 – Residential Field Verification and Diagnostic Test Protocols
3. Turn the cooling system on and let it run for 15 minutes to stabilize temperatures and pressures before
taking any measurements. While the system is stabilizing, proceed with setting up the temperature
sensors.
4. Attach one pipe temperature sensor to the suction line near the suction line service valve and attach
one pipe temperature sensor to the liquid line near the liquid line service valve.
5. Attach a temperature sensor to measure the condenser entering air dry-bulb temperature. The sensor
shall be placed so that it records the average condenser air entering temperature and is shaded from
direct sun.
6. Be sure that all cabinet panels that affect airflow are in place before making measurements. The
temperature sensors shall remain attached to the system until the final charge is determined.
8. Place wet-bulb temperature sensor (cotton wick) in water to ensure it is saturated when needed. Do not
get the dry-bulb temperature sensors wet.
9. Insert the dry-bulb temperature sensor in the supply plenum at the "Title 24 – Supply Temperature
Access" detailed in Section RA3.2.2.2.2.
10. At 12 minutes, insert a dry-bulb temperature sensor and a wet-bulb temperature sensor into the return
plenum at the "Title 24 – Return Temperature Access" detailed in Section RA3.2.2.2.2.
11. At 15 minutes when the return plenum wet-bulb temperature has stabilized, using the temperature
sensors already in place, measure and record the return (evaporator entering) air dry-bulb temperature
(T
return, db) and the return (evaporator entering) air wet-bulb temperature (Treturn, wb).
12. Using the dry-bulb temperature sensor already in place, measure and record the supply (evaporator
leaving) air drybulb temperature (T
supply, db).
13. Using the refrigerant gauge or saturation temperature measurement sensor already attached, measure
and record the evaporator saturation temperature (T
evaporator, sat) from the low side gauge.
14. Using the refrigerant gauge or saturation temperature measurement sensor already attached, measure
and record the condenser saturation temperature (T
eondenser, sat) from the high side gauge.
15. Using the pipe temperature sensor already in place, measure and record the suction line temperature
(T
suction,).
16. Using the pipe temperature sensor already in place, measure and record the liquid line temperature
(T
liquid).
17. Using the dry-bulb temperature sensor already in place, measure and record the condenser (entering)
air dry-bulb temperature (T
condenser, db).
The above measurements shall be used to adjust refrigerant charge and airflow as described in following
sections.
RA3.2.2.6 Refrigerant Charge and Metering Device Calculations
The followi
ng steps describe the calculations to determine if the system meets the required refrigerant charge
and metering device function using the measurements described in Section RA3.2.2.5. If a system fails, then
remedial actions must be taken. If the refrigerant charge is changed and the airflow is being tested with the
Temperature Split Method, then the airflow shall be re-tested. Be sure to run the air conditioner for 15 minutes
after the final adjustments before taking any measurements. Both the airflow and charge must be re-tested until
they simultaneously pass.
RA3.2.2.6.1 Fixed M
etering Device Calculations
The Superheat Charging Method is used only for systems equipped with fixed metering devices. These include
capillary tubes and piston-type metering devices.
1. Calculate Actual Superheat as the suction line temperature minus the evaporator saturation
temperature.