Quote Cart
Superheat Calculator
Calculate refrigerant superheat to verify your expansion device and refrigerant charge are correct. Enter the suction line temperature and evaporator saturation temperature to get instant results.
What is Superheat?
Superheat is the temperature difference between the actual refrigerant vapour temperature at the compressor suction line and the saturation temperature at the same pressure. It ensures all refrigerant has boiled off before entering the compressor, preventing liquid floodback.
A target superheat of 4–8°C is typical for most residential and commercial air conditioning systems. Fixed orifice systems have variable superheat that changes with load, while TXV systems maintain a relatively constant superheat.
Frequently Asked Questions
What should superheat be on an AC unit?
Target superheat is typically 4–8°C for residential and commercial AC. Fixed orifice systems may vary from 5–15°C depending on load, while TXV systems hold closer to 5–7°C.
What happens if superheat is too low?
Low superheat (below 4°C) risks liquid refrigerant entering the compressor, causing floodback, oil dilution, and potential compressor damage.
What causes high superheat?
High superheat indicates insufficient refrigerant flow — caused by undercharge, a restricted expansion device, or a dirty evaporator coil reducing heat transfer.
Superheat Calculator
Related Refrigeration Tools
Subcooling Calculator
Calculate liquid line subcooling to verify condenser charge and performance.
Refrigerant P-T Calculator
Convert refrigerant pressure to temperature and vice versa for common refrigerants.
Refrigerant Charge Calculator
Calculate total refrigerant charge including factory charge and pipe length allowance.
Additional Pipe Length Charge Calculator
Calculate the extra refrigerant needed for additional pipe length beyond standard.
Need Professional Help?
Post a request and get competing quotes from rated HVAC engineers nationwide.