Superheat and Subcool
Superheat or subcool from line temperature and pressure.
Example
You enter
- Refrigerant R-410A
- System pressure (psig) 118
- Line temperature (°F) 50
- Mode superheat
You get
- Saturated temperature 40 F
- Result 10
Checked against published worked examples from: AHRI / manufacturer P-T charts.
Details, formula, and sources
Formula or tableSuperheat = suction-line temperature − saturation temperature at suction pressure. Subcool = saturation temperature at liquid-line pressure − liquid-line temperature.
Source and editionClassical refrigeration cycle; manufacturer P-T tables for the saturation lookup.
Free accessRefrigeration-cycle texts free at university OCW; manufacturer P-T tables free per refrigerant-pt.
What governsEstimate. AHJ and licensed mechanical contractor govern. ACCA Manual J / D / S supersede rules of thumb.
API field namesrefrigerant, system_pressure_psig, line_temperature_F, mode, saturated_temperature_F, superheat_F
- Superheat target manufacturer commissioning guide; typical 10–14 °Fmanufacturer technical bulletin
- Subcool target manufacturer commissioning guide; typical about 8–10 °F, flagged high above 10 °F (2–10 °F reads in range)manufacturer technical bulletin