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Temperature & pressure unit toggles
RefCalc can take field readings in imperial or SI-style units. Preferences apply to all RefCalc inputs (setup, gauges, coil, duct ΔT) and to on-screen results and the diagnostic PDF.
Where to switch
- Setup step — toggles for °F / °C and PSIG / PSIA / kPa.
- Settings — same choices, saved on this device for the next visit.
- Changing either place updates the other (shared device preference).
Temperature (°F / °C)
- Absolute temperatures (line temps, return DB/WB, discharge, water in/out, ODB) convert with the usual formula when you toggle.
- Differences (superheat, subcooling, coil TD, duct ΔT) convert as a scale only (×5/9) — no 32° offset.
- Filled fields convert in place so you can switch mid-job without retyping.
Pressure (PSIG / PSIA / kPa)
- PSIG — gauge pressure (most manifold sets in North America).
- PSIA — absolute pressure (gauge + atmosphere).
- kPa — gauge kilopascals (metric manifold style), not absolute kPa.
- Suction and liquid pressure fields convert when you change mode.
What stays under the hood
- Saturation tables and calculations always use °F and PSIA internally.
- Status bands (e.g. “good” SH/SC) are evaluated on those internal values; displays use your selected units.
- PT chart modal can show °C / kPa and follows your temperature preference when opened.
Not on these RefCalc toggles
- Duct static/total pressure stays in in. w.c.
- FPM, duct area (sq.in.), and tons stay imperial. RefCalc duct volume can display as CFM or L/s (Settings / duct toggle); math stays CFM.
- Settings °F/°C and PSIG/kPa apply to RefCalc, not Air Flow or sizing. Air Flow step 1 shows CFM and L/s (and ΔT °F / ΔT °C) as live pairs; Fan Laws uses the volume toggle.
Tip: Set units before a long job, or switch freely — values already entered are converted. See also Reload last session if you leave and return later.
Disclaimer: Field guide for technicians — not a substitute for nameplate data or local Code.