About HVAC PT Charts
A field reference for HVAC professionals: verified pressure-temperature charts for 61 refrigerants, plus calculators and guides for the daily charging, diagnostic, and retrofit work that depends on them.
What HVAC PT Charts is
HVAC PT Charts is a free reference and tooling resource for refrigerant service technicians, equipment specifiers, and HVAC engineers. The site covers every refrigerant a technician is likely to encounter in modern service — from current A2L refrigerants (R-32, R-454B, R-454C, R-1234yf) to legacy HCFCs still in service (R-22, R-123) to industrial naturals (R-717 ammonia, R-744 CO₂, R-290 propane).
| Refrigerant detail pages | 61 | Full PT chart, properties, safety class, retrofit paths |
| Calculators | 9 | PT, superheat, subcooling, combined, system diagnostic, charge, saturation properties, PT comparison, retrofit compatibility |
| Long-form guides | 5 | PT chart reading, SH/SC fundamentals, high head pressure diagnosis, GWP rankings, safety classifications |
| Operating-pressure references | 9 | R-410A, R-22, R-32, R-454B, R-134a, R-404A, R-407C, R-454C, R-744 |
| Pair comparisons | 13 | R-22 vs R-410A, R-32 vs R-410A, R-410A vs R-454B, plus 10 other retrofit / transition decisions |
How the data is built
Saturation data for the 61 refrigerants in the dataset comes from one of two primary-source paths.
| Source path | Refrigerants | Method |
|---|---|---|
| CoolProp 7.2.0 REFPROP-compatible Helmholtz EOS | ~50 | Generator script computes saturation pressures at every °F from −40 to 150 (or the refrigerant's critical temperature, whichever is lower). Output written to a committed JSON file. |
| Manufacturer datasheets Honeywell, Chemours, Arkema, AGC | ~10 | For blends CoolProp doesn't model (R-448A, R-450A, R-1336mzz(Z), etc.) values come from the named manufacturer datasheet with the URL recorded per refrigerant. When transcription is pending, the page displays an honest disclosure with the source citation — never a fabricated value. |
A build-time verifier cross-checks the data against anchor values (R-22 = 121.44 PSIG at 70°F, R-410A = 201.76 PSIG at 70°F, etc.). If any anchor drifts more than ±5%, or if any saturation pressure exceeds the critical pressure (physically impossible), the build fails. Direct edits to the generated JSON are a code smell — the fix belongs in the source config or the manufacturer-blend skeleton, and the data is regenerated.
Structural guarantees, not careful prose
The data layer is Zod-validated at build time. Safety class is a typed enum; it's structurally impossible to render the wrong class for a refrigerant once the enum value is set correctly. Per-refrigerant prose lives in MDX files separate from templates — templates render structure and data only, so there is no path for refrigerant-A copy to accidentally appear on refrigerant-B's page.
- No fabricated PT values.Every saturation pressure comes from the data layer (CoolProp or named manufacturer datasheet). Refusal is structural: when source data isn't available, the page shows an honest disclosure naming the missing source, not a guess.
- No template-swap copy.Refrigerant-specific prose lives only in per-refrigerant MDX. Templates can't print refrigerant-specific copy from the dataset layer.
- Safety class is structural. Zod enum + dedicated component. R-32 cannot accidentally display A1; the data layer says A2L and the component renders the correct chip.
- Every claim has a source. Source registry in the repo; inline citations on each refrigerant page; provenance footer on every page.
- Anchor verifier blocks the build. If PT data drifts outside ±5% of anchored reference values, or if any saturation pressure exceeds the critical pressure, the build fails before deploy.
Editorial principles
Per-refrigerant prose is written in MDX files — one per refrigerant — separate from the page templates. Templates render the structural sections (PT chart, properties grid, comparison cards) from the data layer; MDX provides the narrative context (history, applications, retrofit guidance, service notes). A page without MDX renders honestly: data sections appear, narrative sections are omitted — no substituted boilerplate.
- No paragraph over 3 sentences. Information density is high; text walls are not.
- Every factual claim cites a source from the source registry.
- Reference values (NBP, Tcrit, GWP, etc.) come from the data layer, not from prose retyping.
- No fake author personas. Author = the Organization.
- No emoji as decoration. Use icons (lucide-react) when a visual marker is needed.
- No paywalls, no signup, no email harvesting. Display advertising via Raptive supports the cost of keeping the dataset free.
Open data
The full PT chart for every refrigerant is downloadable as CSV or JSON from the refrigerant's detail page footer. The complete dataset is licensed under Creative Commons Attribution 4.0. Use it for HVAC service apps, training simulators, OEM internal tooling, academic research, building-energy modeling, or any other purpose — attribute the source and the underlying primary source for the specific values (CoolProp citation, manufacturer datasheet citation).
The site itself is a Next.js 16 application, statically generated. Source data is committed to git; the calculator math is open in the page bundles. For bulk programmatic access, the master dataset is available at /api/refrigerants.json (also CC BY 4.0).
What this site is not
HVAC PT Charts is reference material, not replacement for formal HVAC training, equipment OEM service literature, or jurisdictional code compliance. A few intentional non-features:
- Not a substitute for EPA Section 608 certification. Legal handling of refrigerants in the US requires Section 608 certification. The site does not replace the formal training pathway.
- Not a substitute for equipment OEM service literature. Reference targets here (target superheat / subcooling, charge nameplate values) are generic. Always defer to the equipment OEM's charging procedure for the specific equipment.
- Not a Manual J load calculator. Heat load and equipment sizing belong in ACCA Manual J / S / D software (Wrightsoft, Elite, CoolCalc). This site covers refrigerant-side service measurement, not upstream load calculation.
- Not a live refrigerant price feed. Distributor pricing changes with AIM Act allocations, weather, and import dynamics. Use your distributor for current quotes.
- No user accounts, no signup, no chat AI bolted on top. The site is what it is: structured data, calculators, and reference guides. Visit, look up what you need, leave.