Subcooling & Superheat Calculator
Diagnose system performance from pressure and temperature
Zeotropic Refrigerant Selected: This refrigerant has temperature glide. For accurate readings: use Dew Point for superheat calculation and Bubble Point for subcooling calculation. The calculator uses average values - for critical applications, refer to separate dew/bubble point P-T tables.
⚠️ HIGHLY FLAMMABLE REFRIGERANT (A3 Class): This refrigerant is extremely flammable with a low ignition energy. Safety requirements: No open flames, no sparking tools, ensure adequate ventilation, follow local safety codes. Maximum charge limits apply - typically 150g for domestic appliances. Only certified technicians should handle this refrigerant.
⚠️ TOXIC REFRIGERANT (B2L Class): R-717 (Ammonia) is toxic and mildly flammable. Safety requirements: Gas detection required, emergency ventilation, PPE (respirator, goggles, gloves). Exposure limit: 25 ppm TWA. Immediately evacuate area if leak detected. Industrial/commercial use only.
⚠️ HIGH PRESSURE REFRIGERANT: R-744 (CO2) operates at extremely high pressures (up to 1500+ psig). Safety requirements: Specialized high-pressure equipment required, pressure relief devices mandatory. Critical point: 31.1°C / 1070 psig. Transcritical operation above critical point. Ensure gauges rated for CO2 service.
Typical range: 150-500 psig
Typical range: 50-200 psig
Measured at liquid line near condenser
Measured at suction line near compressor
Saturation Temperatures (from P-T Chart)
Results
System Diagnosis
Diagnostic Reference
High Superheat + Low Subcooling
Likely cause: Low refrigerant charge
Action: Check for leaks and add refrigerant
Low Superheat + High Subcooling
Likely cause: Overcharge
Action: Recover excess refrigerant
High Superheat + Normal/High Subcooling
Likely cause: Restricted metering device, low airflow
Action: Check TXV, filter, and evaporator coil
Normal Superheat + Normal Subcooling
Status: System operating correctly
Action: No adjustment needed
Formulas
Superheat = Suction Line Temp - Low Side Sat. Temp
Subcooling = High Side Sat. Temp - Liquid Line Temp