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Superheat and Subcooling Calculator

HVAC Tools

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.

How to Use Superheat and Subcooling Calculator

1. Select refrigerant type (R-410A, R-22, or R-134a) from the dropdown. 2. Select what you're calculating: Superheat or Subcooling. 3. Enter the pressure reading (from manifold gauge). 4. Enter the actual line temperature at the measurement point. 5. Click "Calculate" — the tool will: • Use the PT chart to convert pressure to saturated temperature. • Apply the formula: - Superheat = Actual Temp – Saturated Temp (for suction line) - Subcooling = Saturated Temp – Actual Temp (for liquid line) 6. Compare the result to the system’s target value (from the nameplate). - High subcooling = likely overcharged - Low subcooling = likely undercharged - High superheat = likely underfed - Low superheat = risk of floodback

Frequently Asked Questions

Do I need to know the metering device type?

Yes. Use subcooling if your system has a TXV. Use superheat if your system uses a fixed orifice or piston.

Where do I measure the pressure?

Measure suction pressure near the evaporator outlet for superheat. Measure liquid pressure at the condenser outlet for subcooling.

Where do I measure the temperature?

For superheat: on the suction line near the evaporator outlet. For subcooling: on the liquid line near the condenser outlet.

What is a typical subcooling target?

Most systems with TXVs target 8°F to 12°F. Check the system nameplate for the exact value.

What is a typical superheat target?

It varies based on indoor wet bulb and outdoor dry bulb, but typically ranges from 8°F to 20°F.

What is a Saturation Temperature in HVAC ?

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.