🔍 Key Concepts

• Evaporator pressure regulator (EPR) valve function in multi-box (multi-evaporator) systems • Relationship between evaporator pressure and evaporator temperature (pressure–temperature chart for the refrigerant) • Difference between individual box temperature control and compressor suction pressure control

💭 Think About

• Ask yourself: Does this valve mainly protect against pressure getting too high, too low, or is it balancing conditions between multiple boxes? • Think about what happens to the evaporator temperature when the pressure in that evaporator drops too far for a given refrigerant. • Which component in a refrigeration system is normally responsible for controlling overall suction pressure: an EPR valve at each box, or another control closer to the compressor?

✅ Before You Answer

• Verify which device is normally used to protect against excessively low coil temperatures (and coil icing) in individual boxes. • Check whether an evaporator pressure regulator is installed on each evaporator or only at the compressor suction line. • Confirm whether the purpose of the EPR is more about local evaporator conditions or system-wide suction control/balancing.