Enter the suction line temperature (measured at the evaporator outlet / compressor inlet) and the saturation temperature (the refrigerant saturation temperature that corresponds to the measured suction pressure for the same refrigerant) into the Superheat Calculator. You may use °F or °C. The calculator will evaluate the superheat.
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Superheat Formula
The following example problem outlines the steps and information needed to calculate the superheat.
SH = T_{\text{suction}} - T_{\text{sat}}Variables:
- SH is the superheat (a temperature difference, in °F or °C)
- Tsuction is the measured refrigerant vapor temperature at the evaporator outlet / suction line (often measured near the compressor inlet), in °F or °C
- Tsat is the saturation temperature that corresponds to the measured suction pressure for the same refrigerant, in °F or °C
To calculate the superheat, subtract the saturation temperature (from pressure) from the measured suction line (vapor) temperature.
How to Calculate Superheat?
The following steps outline how to calculate the superheat.
- First, measure the suction line (vapor) temperature at the evaporator outlet / compressor inlet (°F or °C).
- Next, measure the suction pressure and use the correct refrigerant P-T chart (or gauge scale) to determine the corresponding saturation temperature (°F or °C).
- Next, gather the formula from above: SH = Tsuction – Tsat.
- Finally, calculate the superheat.
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
suction line temperature (°F) = 51
saturation temperature (°F) = 24
SH = Tsuction – Tsat = 51 – 24 = 27 °F
