Superheat Calculator - HVAC

HVAC Superheat & Subcool Calculator is the professional field diagnostic tool for AC service and system commissioning. Calculate superheat, subcooling, and saturation for 20 refrigerants including R-410A, R-454B (EPA 608 transition), and R-32 with smart charge diagnostics and color-coded results for instant field diagnostics.

FEATURES:
Instant Superheat & Subcooling Calculation — Get results in seconds
Smart Charge Diagnostics — Normal, Low, or High with recommendations
20 Refrigerants Supported — R-410A, R-22, R-454B, R-32, R-407C, R-134a, R-404A, R-507A, R-290, R-717, R-12, R-502, R-1234yf, R-448A, R-449A, R-513A, R-744, R-600a, R-407A, R-422D
Metering Device Support — TXV (expansion valve) or fixed orifice
Color-Coded Results — Green/yellow/red for quick decisions
P-T Saturation Data — NIST REFPROP-grade, verified against manufacturer charts
Zeotropic Blend Support — Correct bubble/dew handling for blends

100% OFFLINE:
All refrigerant data built-in. Works on job sites without cellular coverage.

HOW IT WORKS:
1. Select refrigerant (R-410A, R-454B, R-32, etc.)
2. Select metering device (TXV or fixed orifice)
3. Enter suction pressure & temperature
4. Enter liquid pressure & temperature
5. Get instant superheat, subcooling & charge diagnosis

UNDERSTANDING RESULTS:
Superheat — Temperature rise above saturation on low side. Normal 10-20°F TXV, 15-25°F fixed orifice. Low indicates overcharge; high indicates undercharge or low airflow.

Subcooling — Temperature drop below saturation on high side. Normal 10-20°F. Low indicates undercharge; high indicates overcharge.

DIAGNOSTICS:
Green — Normal charge, optimal operation
Yellow — Borderline condition requiring attention
Red — Undercharge, overcharge, or airflow issue

SUPPORTED REFRIGERANTS:
R-410A (residential), R-22 (legacy), R-454B (EPA replacement), R-32 (mini-splits), R-407C (commercial), R-134a (auto AC), R-404A (refrigeration), R-507A (low-temp), R-290 (propane), R-717 (ammonia), R-12 (legacy CFC service), R-502 (legacy low-temp), R-1234yf (auto AC), R-448A and R-449A (R-404A replacements), R-513A (R-134a replacement), R-744 (CO2), R-600a (domestic refrigerators), R-407A (R-22 retrofit), R-422D (R-22 drop-in)

OPTIONAL PRO UPGRADE — $2.99 ONE-TIME IN-APP PURCHASE
The following features require a separate one-time in-app purchase. They are not required to use the calculator:
• Unlimited saved calculation history
• PDF export of results
• Dark theme
• Ad-free experience

USE CASES:
AC service calls, refrigerant charge diagnostics, equipment commissioning, troubleshooting complaints, EPA 608 certification study, preventive maintenance checks, system optimization, R-454B transition preparation.

PERFECT FOR:
HVAC technicians, refrigeration mechanics, AC contractors, HVAC apprentices, building engineers, commissioning specialists, HVAC students.

All P-T saturation data from NIST REFPROP-grade equations of state, cross-checked against manufacturer charts, covering -60°F to +150°F, with correct bubble/dew blend calculations.

Part of HVACTools Suite — professional HVAC technician tools for field service and diagnostics.

Recent changes:
Added 10 refrigerants: R-12, R-502, R-1234yf, R-448A, R-449A, R-513A, R-744 (CO2), R-600a, R-407A, R-422D — now 20. Saturation tables from NIST REFPROP-grade data, checked against manufacturer charts.