Also know as:
- Pressure reducer valve
- Two temperature valve
- Constant valve
- Valve operation ORI (opens on a rise of inlet)
Purpose:
- To prevent an evaporator from going below a set predetermined pressure (temp)
Types:
- Pressure operated
- Temperature operated
Application:
- Any application where a abnormal Low Temp. could create a problem
- On system operating two or more conditioned spaces at different temperature
- On ammonia system, one setting used for operating cycle, the other setting used during defrost mode (two temperature valve)
- Controlled evaporator must not exceed 40% of total load
- Check valve must be located at outlet of coldest coil
Location:
- Outlet of the evaporator
- Multiple temperature system at outlet of warmest coil
- Required if temperature diff. between warmest and coldest exceed 5 degrees F
Considerations:
- @ 40% EPR load, system may require capacity control using a discharge bypass valve to compressor
- control using a discharge bypass valve to compressor suction, along with desuperheating expansion valve (quenching valve)
ot gas bypass to suction)
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