Superheat & Subcooling Calculator

Read the suction (low-side) pressure and convert it to the saturation temperature with the refrigerant's PT chart. Measure the suction line temperature near the service valve. Superheat = suction line temperature − saturation temperature. For blends with glide such as R-454B or R-407C, use the dew point (vapor) column.

Read the liquid (high-side) pressure and convert it to the saturation temperature. Measure the liquid line temperature near the service valve. Subcooling = saturation temperature − liquid line temperature. For blends with glide, use the bubble point (liquid) column.

Fixed-orifice (piston) systems are charged by superheat against a target from the outdoor and indoor conditions. TXV and EEV systems are charged by subcooling against the target on the outdoor unit's nameplate or the manufacturer's charging chart. Always follow the manufacturer's instructions for the specific unit.

No. R-454B is an A2L (mildly flammable) refrigerant for equipment designed for it, with its own pressures, glide and safety requirements. Use the R-454B chart, not the R-410A one, and follow the A2L handling rules.

From the published Arkema Forane® pressure–temperature charts (NIST REFPROP data). Between the printed 5 °F points the calculator interpolates along the vapor-pressure curve. It is a reference tool: verify against the equipment manufacturer's data.