Superheat is the temperature difference between the refrigerant gas leaving the evaporator coil and the refrigerant’s boiling point at that pressure. It’s measured in degrees F, typically 8-12°F for a properly charged AC system.
Why it matters: liquid refrigerant entering the compressor is catastrophic — it doesn’t compress and can destroy the compressor. Superheat ensures all the refrigerant has fully evaporated to gas before reaching the compressor. Too little superheat = liquid floodback risk. Too much superheat = system is undercharged and inefficient.
What superheat readings tell us
- 0-5°F superheat — danger zone. Possible liquid floodback. Overcharged or TXV problem.
- 8-12°F superheat — normal, target range for most systems
- 15-25°F superheat — undercharged or restricted refrigerant flow
- 30+°F superheat — significantly undercharged. Refrigerant leak likely.
Measuring superheat (and subcool) is what separates a proper commissioning from “topping off the freon.” It’s how we know the system is actually performing as designed, not just guessing.
Related: Subcool, Refrigerant, TXV, Compressor.
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Right Way Mechanical is a family-owned HVAC contractor serving Wheat Ridge, Arvada, west Denver, and the Colorado foothills.