17
Evaporator Superheat
• Check the evaporator superheat once the walk-in has reached the desired temperature. Generally, systems with a
design temperature drop of 10°F should have an evaporator superheat value of 6°-10°F on freezers and 8°-12°F on
coolers for maximum efficiency.
• To determine the evaporator superheat:
o Measure the suction pressure at the evaporator outlet.
o Convert the pressure to saturation temperature referencing a temperature-pressure chart.
o Measure the temperature of the suction line at the expansion valve bulb. Ensure the bulb is mounted at the
correct location on the suction tube.
o Subtract the saturation temperature reading (step 2) from the measured temperature (step 3). The
difference is the evaporator superheat.
pressure converted to
temperature equals
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