Accurately calculate superheat or subcooling for HVAC systems using R-410A, R-22, or R-134a. Ideal for verifying refrigerant charge on systems with TXV or fixed orifice metering devices.
This tool is designed to translate real-world HVAC measurements into actionable diagnostics using precise pressure–temperature (PT) relationships for the industry's most common refrigerants, including R-410A, R-22, R-134a, R-32, and R-454B. By utilizing embedded PT data with intelligent interpolation, the calculator accurately estimates saturation temperatures directly from your gauge pressure readings.
To accommodate different field preferences, the tool supports two distinct workflows. In PT Chart Mode, saturation temperature is derived automatically from your pressure inputs for both low-side and high-side calculations. For those preferring specialized reference material, the Manual Mode allows you to directly input saturation and line temperatures from external charts or verified manufacturer values.
The calculator provides two critical performance metrics: Superheat, which compares suction line temperature to evaporator saturation to assess compressor protection and evaporator efficiency; and Subcooling, which compares liquid line temperature to condenser saturation to evaluate the refrigerant charge—essential for systems utilizing a Thermal Expansion Valve (TXV).
To ensure global utility, all inputs support both °F and °C with consistent internal conversion for maximum accuracy. Because results are based on interpolated reference data, they are intended as high-quality field estimates. For the most reliable diagnostics, ensure proper sensor placement and wait for stable operating conditions before taking your final readings.
Yes. Use subcooling if your system has a TXV. Use superheat if your system uses a fixed orifice or piston.
Measure suction pressure near the evaporator outlet for superheat. Measure liquid pressure at the condenser outlet for subcooling.
For superheat: on the suction line near the evaporator outlet. For subcooling: on the liquid line near the condenser outlet.
Most systems with TXVs target 8°F to 12°F. Check the system nameplate for the exact value.
It varies based on indoor wet bulb and outdoor dry bulb, but typically ranges from 8°F to 20°F.
Saturation temperature is the temperature at which a substance changes phase — typically between liquid and vapor at a given pressure. When a liquid absorbs heat the temperature increases up to a certain point where the heat absorbed changes the phase of the liquid instead of increasing the temperature. For a liquid turning to vapor (boiling), the saturation temperature is the boiling point and for a vapor turning to liquid (condensation), the saturation temperature is the condensation point.