How do you calculate R-454B superheat?
Enter suction pressure (psig) and suction line temperature (°F). For R-454B, superheat uses dew-point saturation temperature. The app selects dew point automatically so you do not mix bubble and dew.
R-454B · R-32 · R-410A
R-454B superheat and A2L max charge on your phone.
Gauge pressure and line temp in, superheat or subcooling out, with R-454B bubble and dew points handled correctly. Room dimensions in, maximum allowable A2L charge out. Two inputs. One answer. Under 30 seconds — even with zero bars.
- Free
- iPhone & iPad
- Works offline
- No account
Take A2L charging math offline. PT tables travel with the app — no signal required.
In the field
Charging and A2L safety math on one screen.
Who it’s for
Making the jump from R-410A? So is everyone.
Built for residential HVAC techs and apprentices moving to R-454B and R-32. The new refrigerants need different PT references, glide handling, and room safety math than what you have been running for a decade. This puts R-454B superheat and A2L max charge on your phone instead of scattered across manufacturer PDFs.
- Superheat and subcooling in seconds. Enter suction or liquid pressure in psig and line temp in °F. Get the actual number with typical-range context and an optional OEM target comparison.
- Glide handled right. R-454B superheat uses dew point, subcooling uses bubble point, automatically. The app will not let you mix them up.
- Max allowable charge from room dimensions. Length, width, and mount location in. Max A2L charge in pounds out, for floor, wall, or ceiling units.
- Active mitigation toggle. Systems with leak detection and response controls get the expanded limit. The passive number stays on screen for reference.
- PT tables built in. R-454B, R-32, and R-410A data ship inside the app. Basements, mechanical rooms, rooftops. Zero bars, full function.
- A2L quick reference. Refrigerant comparison, safety rules, and a bubble-and-dew explainer. The cheat sheet stays in your pocket.
- PDF job reports. Export any calc as a one-page PDF with your company name, tech name, and license number. Generated entirely on the device.
- History that writes the ticket. Every calc auto-saves with a timestamp and optional job label. Pull it back up at the truck.
The numbers behind the numbers
Sourced data, shown sources.
- Max charge formula: structured per UL 60335-2-40 / ASHRAE Standard 15.2, with the attribution shown on every result and PDF.
- Flammability limits: LFL values from ASHRAE 34-2022 (R-454B 0.303 kg/m³, R-32 0.307 kg/m³), with installation heights for floor, wall, and ceiling mounts.
- Active mitigation: expanded limit attributed to UL 60335-2-40 Ed. 3 Annex GG.
- PT data sources shown on every result: Chemours Opteon XL41 (NIST REFPROP 10.0) for R-454B, Daikin / Hudson Technologies (NIST) for R-32, National Refrigerants Reference Guide 7th Ed. for R-410A.
- Field units throughout: °F, psig, square feet, pounds.
- Honest results: typical ranges are shown for context, never pass-fail badges, and every result carries a disclaimer. It is a calculation aid, not a substitute for the OEM charging procedure or code compliance. The OEM plate overrides field bands.
Common questions
R-454B superheat and A2L max charge FAQ
Do you use bubble or dew point for R-454B?
Use dew-point saturation temperature for superheat and bubble-point saturation temperature for subcooling. The app selects the correct value automatically.
How is A2L max charge calculated?
Enter room length, width, and mount location (floor, wall, or ceiling). The app estimates maximum allowable charge using methods structured per UL 60335-2-40 and ASHRAE Standard 15.2, with an active-mitigation option when leak detection and response controls are present. OEM nameplate and local code still override field estimates.
Does the charging calculator work offline?
Yes. Pressure-temperature data for R-454B, R-32, and R-410A is stored in the app, so R-454B superheat and A2L max charge calculations work without an internet connection.
Is this a substitute for the OEM charging procedure?
No. A2L Safe Charge is an informational estimating aid for qualified technicians. Results are estimates, not code compliance. Follow the equipment manufacturer’s charging procedure and applicable codes; the OEM plate overrides field bands.
Which refrigerants are supported?
R-454B, R-32, and R-410A, with PT tables, glide handling where applicable, and flammability reference data for the A2L refrigerants.
Get it offline
Free. On your gauges’ side before the next A2L call.
Install once. Run R-454B superheat and A2L max charge in the mechanical room when cellular is gone — PT tables never leave the device.
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