What is Superheat and how do I measure it?

Superheat is the temperature of vapor above the boiling temperature of its liquid at that pressure. To measure superheat, perform the following steps.

1. Convert suction pressure to temperature, using a temperature/ pressure chart for the specified refrigerant.

2. Measure the suction line temperature near the service valve.

3. Subtract the pressure to temperature conversion from the suction line temperature. This results in the system superheat.

Example:

A suction pressure of 65 converts to a temperature of 37 degrees.
The measured suction line temperature is 53 degrees.
53 minus 37 equals 16, or 16 degrees of superheat.