Superheat is a technical term used in HVAC that measures the amount of heat added to a vapor above its boiling point. It shows the amount of heat that the refrigerant has gathered over time. Superheating occurs when a gas is heated above the boiling point of that element in its liquid form. It is calculated as the difference between the saturation temperature of a substance and the actual temperature of the gas. In HVAC, refrigerants often boil at much lower temperatures than water. Superheat is important because it ensures that the liquid refrigerant is boiled off before it leaves the evaporator and heads to the compressor. If the superheat reading is too high, there isn’t sufficient refrigerant, and the system will be inefficient. But if it’s too low, there’s too much liquid in the evaporator, which could damage the compressor. To measure superheat, one needs to measure the suction pressure of the compressor using a gauge manifold, use a corresponding pressure chart to calculate the boiling point, let the unit run for about 15 – 20 minutes, and use a temperature probe to gauge the amount of refrigerant coming from the evaporator. Then subtract the saturation temperature to get the superheat measurement.