Superheat & Subcooling Calculator
Enter a line pressure and temperature. Get superheat or subcooling for 19 refrigerants.
How to use ↓Enter the pressure and the line temperature.
How to use
- Pick the refrigerant and choose Superheat or Subcooling.
- Superheat: suction pressure, and the suction line temperature near the evaporator outlet or the compressor.
- Subcooling: liquid line pressure, and the liquid line temperature near the condenser outlet.
- Compare with the target on the equipment’s charging chart or the manufacturer’s instructions.
How it works
Superheat is the line temperature minus the saturation temperature at the suction pressure. Subcooling is the saturation temperature at the liquid pressure minus the line temperature. For blends the calculator uses the vapor (dew) value for superheat and the liquid (bubble) value for subcooling, from the same tables as the PT charts.
FAQ
Why dew for superheat and bubble for subcooling?
Blends with glide boil and condense over a range. Vapor in the suction line leaves at the dew point; liquid leaving the condenser starts at the bubble point.
What does a negative result mean?
Usually a reading is off, the probe is in the wrong place, or the wrong refrigerant is picked. Check the gauges and the thermometer first.
What superheat or subcooling should I aim for?
It depends on the system and its metering device. Use the target from the equipment’s charging chart or the manufacturer’s instructions.