🔍 Key Concepts

• Solenoid valve orientation in refrigeration systems (effect of gravity and valve design) • What the box thermostat is actually measuring and controlling in a refrigerated box • Normal location of a liquid-line solenoid valve relative to the thermal expansion valve (TXV)

💭 Think About

• Ask yourself: Should the solenoid valve control based on the box air temperature or evaporator superheat, and which device normally controls superheat? • Consider whether the solenoid should see high-pressure liquid or low-pressure mixture/vapor—does that place it before or after the thermal expansion valve? • Think about how most solenoid coils and plungers are designed to sit—does their construction usually require a specific upright or horizontal position?

✅ Before You Answer

• Verify what device is normally responsible for controlling evaporator superheat in a TXV system • Check where the liquid line is in relation to the thermal expansion valve and where a solenoid is typically installed in that line • Confirm common manufacturer recommendations for mounting orientation (upright vs horizontal) for box solenoid valves in refrigeration service