HVAC Calculators

HVAC service measurements are inherently quantitative — superheat, subcooling, condenser approach, and refrigerant charge all reduce to PT chart lookups plus arithmetic. The calculators on this site formalize that arithmetic with verified saturation data so the only thing a technician needs to bring to the field is accurate pressure and temperature readings.

The previous WordPress version of this site shipped with approximately 25,000 fabricated quantitative errors — PT values wrong by 2-15×, some above critical pressure (physically impossible), several A2L/A3/B2L refrigerants classified as "A1 non-flammable" (safety-critical misclassifications). The current rebuild was structured specifically to make those failure modes impossible: every value comes from CoolProp 7.2.0 or a cited manufacturer datasheet, safety class is a Zod enum (impossible to display the wrong class), and any input outside the valid chart range returns "out of range" instead of an extrapolated number.

This means the calculators here are deliberately less "smart" than some competitors — they refuse to guess. That's the feature, not a bug.

Saturation data: CoolProp 7.2.0 (Bell, Wronski, Quoilin, Lemort 2014, doi:10.1021/ie4033999) implements REFPROP-compatible Helmholtz EOS for pure refrigerants and predefined mixtures. Cross-checked against AHRI Standard 700-2019 specifications where applicable. For 11 manufacturer-blend refrigerants not in CoolProp's library (R-448A, R-450A, R-1336mzz(Z), etc.), values come from named manufacturer datasheets (Honeywell, Chemours, Arkema, AGC).

Target SH and SC ranges: ACCA Manual T (2017) for fixed-orifice charging charts and diagnostic patterns; ASHRAE Handbook of Refrigeration 2022 (Chapter 23) for application-specific target ranges; equipment OEM service literature (Carrier, Trane, Lennox, Daikin, Goodman, Mitsubishi) for equipment-specific setpoints; AHRI Standard 540-2020 for compressor protection minimums.

Regulatory context: EPA AIM Act (40 CFR Part 84) for HFC phase-down dates and GWP caps; ASHRAE Standard 34-2022 for safety classifications; IEC 60335-2-40 for A2L equipment requirements; EPA Section 608 for refrigerant handling and leak repair.

Every claim on every calculator page traces to one of these primary sources. The footer of each calculator lists the specific sources used.

Equipment-specific charge values. The calculators reference equipment OEM literature for nameplate charge but don't store per-model factory charges. Always read the nameplate or service manual for the specific equipment being serviced.

Real-time pricing or availability. Refrigerant prices and supply fluctuate based on AIM Act allocations, weather, and import/export dynamics. Use distributor pricing for current quotes.

Equipment-specific charging procedures. The calculators surface the general procedure (charge by SC on TXV, charge by SH on fixed-orifice with ACCA Manual T chart). Specific equipment may have OEM-specific procedures that override the general approach — always check.

Real-time diagnostic recommendations. The diagnostic calculators surface pattern-matched root causes and ordered investigation steps; they don't replace technician judgment. Treat the flags as "here's what to investigate first" rather than "here's the definitive answer."

For these, refer to the specific equipment OEM, your distributor, and your own field experience — the calculators are a thinking aid, not a replacement.

The first version of these calculators shipped on WordPress with approximately 25,000 fabricated quantitative errors — PT values wrong by 2-15× across the dataset, several values physically impossible (above critical pressure), and safety-critical misclassifications (A2L/A3/B2L refrigerants labeled "A1 non-flammable"). That version of the site was technically a calculator but structurally a liability — a technician trusting the numbers risked equipment damage or safety incidents.

The current rebuild started from the data layer. Every refrigerant property comes from a primary source (CoolProp 7.2.0 / NIST REFPROP / manufacturer datasheet); every value passes Zod schema validation at build time; safety class is a typed enum so the wrong class cannot be displayed; values outside the valid range return "out of range" instead of an extrapolated fabrication. The calculator code then sits on top of this verified data layer with minimal computation — usually just unit conversion, interpolation between adjacent data points, and pattern-matched diagnostic logic from ACCA Manual T.

This means the calculators are deliberately "thin" — they do less than some competitors but the small amount they do is verifiable. Each calculator page lists every source feeding into the calculation. The downloadable refrigerant dataset under CC BY 4.0 is the same dataset the calculators read from, so independent verification is possible.

The trade-off is conservatism: when a refrigerant has limited published data, the calculator reports "out of range" rather than guessing. For mainstream HVAC refrigerants (R-22, R-410A, R-32, R-454B, R-134a, R-407C, R-404A, R-454C, R-744, etc.), data coverage is comprehensive across the full operating envelope. For specialty or very rare refrigerants, coverage is intentionally limited to what's verifiable from primary sources.