HVAC Pro Calculator: NEC + P-T

HVAC Pro Calculator — BTU load sizing, duct calc, NEC voltage drop, refrigerant P-T charts, superheat & subcooling, plus camera nameplate scanning. For HVAC techs and electricians. Cited formulas (ASHRAE, NEC, SMACNA). No ads, no tracking. WHAT YOU GET — FREE • BTU & Cooling Load — Heat and cool sizing using ASHRAE-derived rules of thumb. Square footage, ceiling height, climate zone, occupancy, and sun exposure. • Unit Converter — BTU/hr, kW, tons; CFM to L/s and m³/h; °F/°C; PSI to kPa and bar. • Save up to 2 jobs — Name and store calculations. Attempts private iCloud sync when available; no in-app sync switch or separate app account. UPGRADE TO PRO — 10 field calculators, PlateScan and Speak to Fill • PlateScan — Point your camera at a condenser or heat-pump data plate. On-device OCR reads the model and serial, then decodes tonnage, manufacture date, and likely refrigerant and offers them to your calculators. Not for furnaces or air handlers. Works offline. • Speak to Fill — Say the field and the number: "suction line temp fifty-two." Review before it fills. On-device, English only. • Duct Sizing — Manual D simplified via the ASHRAE friction-rate equation. Round and rectangular duct, equivalent-diameter solver, velocity check with noise warnings. • Voltage Drop & Wire Size — NEC voltage-drop formula, 1- or 3-phase, copper or aluminum. Recommends the smallest AWG that meets your drop limit, NEC 310.16 ampacity for that conductor, and 240.4(D) breaker limits. • Refrigerant P-T Charts — Pressure ↔ temperature for R-410A, R-32, R-454B, and R-22. Saturation tables from CoolProp data, cross-checked against manufacturer charts; interpolated in range. • Superheat & Subcooling — Charging diagnostics off the P-T tables. Enter the target from the unit's charging chart or nameplate and the badge reads On Target, Add Charge, or Recover Charge (±3°F). Leave it blank and you get the number only. • Refrigerant Charge — Adjusts the nameplate charge for non-standard line-set length (per Copeland AE 17-1335) and returns the exact amount to add or recover. • System Capacity (ΔT) — Actual sensible capacity an installed system is delivering, from measured airflow and supply/return temperature split. • Psychrometric — Enter dry bulb plus wet bulb, RH, or dew point; returns the full state: humidity ratio, enthalpy, specific volume, and the remaining temperatures (ASHRAE Fundamentals Ch. 1). • Fan Laws — Scales CFM, static pressure, and brake horsepower from a known operating point to a new RPM. • Sheet Metal Offset — Diagonal cuts and angles for duct transitions, per SMACNA HVAC Duct Construction Standards. • Capacitor Test — Actual μF of a run capacitor from in-circuit amps and volts, with a WITHIN TOLERANCE, MARGINAL, or REPLACE verdict. • Unlimited Saved Jobs — Remove the 2-job cap; save every calculation by job name. • PDF Export — One-tap PDF of the result and readings, for the customer or the job file. WHY PROS PICK HVAC PRO • Cited sources, not "approximate." Every formula references its standard (ASHRAE, NEC, SMACNA, manufacturer P-T tables). Warnings flag out-of-range readings. • Field-ready, high-contrast layout for one-handed use. • No ads, tracking, or separate app account. • Built in SwiftUI for iPhone and iPad, iOS 17 or later. Calculators work offline. PRICING HVAC Pro is a yearly (3-day free trial) or monthly subscription. Your price shows in the app first. One subscription unlocks every Pro calculator, PlateScan, unlimited saved jobs, and PDF export. Cancel anytime in Settings > Apple ID > Subscriptions. Auto-renews until canceled. — Built by PLAYRIOT LLC. Calculations are estimates intended for trade professional use. For code-compliant Manual J load submittals, use ACCA-certified software. Support: https://hvacprocalculator.com/support Privacy: https://hvacprocalculator.com/privacy Terms: https://hvacprocalculator.com/terms Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/