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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:
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
o
correct location on the suction tube.
Subtract the saturation temperature reading (step 2) from the measured temperature (step 3). The
o
difference is the evaporator superheat.
Temperature
Temperature minus
pressure converted to
temperature equals
superheat
Pressure
17
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