Calculators

Refrigerant and system check calculators

Charging and checking a system comes down to a few readings: suction and liquid line pressures and temperatures, indoor wet-bulb, outdoor dry-bulb, and the temperatures across the coil. These calculators turn those readings into superheat, subcooling and split.

Pressure-temperature data comes from CoolProp and is checked against manufacturer charts. For blends with glide, the calculators read the dew line for superheat and the bubble line for subcooling. The manufacturer's charging chart and installation instructions still govern.

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Which one you need

Every tool in this section

  • Refrigerant charge

    Superheat and Subcooling Calculator

    Superheat and subcooling from gauge readings for R-410A, R-454B, R-32 and R-22.

    Reads the dew point line for superheat and the bubble point line for subcooling, and gives a fixed-orifice target from indoor wet-bulb and outdoor dry-bulb.

    Based on CoolProp PT data, manufacturer charging charts

  • Refrigerant charge

    Refrigerant PT Chart

    Saturation pressure from temperature and temperature from gauge pressure for R-454B, R-410A, R-32 and R-22.

    Shows the dew and bubble point lines and the glide on blends, with an optional elevation correction for gauges above sea level. Refuses readings outside -40 to 140°F instead of extrapolating.

    Based on CoolProp PT data, checked against Daikin, Honeywell and Chemours charts

  • Diagnostics

    AC Temperature Split Calculator

    Expected cooling split from SHR and CFM per ton, or delivered BTU/h and SHR from your readings.

    Delivered mode uses return and supply dry-bulb and wet-bulb with the ASHRAE enthalpy equations. Cooling only, no charge diagnosis, no model ratings.

    Based on ASHRAE Fundamentals psychrometrics

  • Refrigerant charge

    Line Set Charge Calculator

    Ounces to add past the factory line length, from the rate in your installation instructions.

    Reference liquid per foot from ACR tube ID and CoolProp density. No line sizing and no A2L charge limit.

    Based on Manufacturer's rate, Goodman TP-107M example

  • Diagnostics

    Furnace Temperature Rise Calculator

    Rise from supply and return readings against the rating plate range, the CFM that rise implies, or the rise at a given CFM.

    Enter the return and supply temperatures and the rise range from the rating plate for a verdict, and the furnace output (or input and AFUE) for an airflow estimate. Or enter the output and CFM for the expected rise. Elevation is corrected with the ASHRAE standard atmosphere. Gas furnaces only; the output is not derated for altitude.

    Based on Furnace manufacturers' instructions, ASHRAE Fundamentals Ch. 1 (1.08)

Other calculators

Every calculator here lists the standard it works from and what it leaves out. The numbers are for sales-phase sizing and field checks, not a permit submittal. Methodology lists the standard behind each one.