What the checklist does
The rules organize reported observations; they do not measure temperatures or electrical power. Reported smoke/electrical warnings come before mode guidance. A home continuing to get colder or persistent equipment concerns leads to professional help even if possible defrost or recovery is also selected. Unknown safety or operation answers never become reassurance.
An occasional Aux message can be consistent with normal control only in a limited context: no reported hazard, home warming and outdoor unit appearing to run. That is still not a fault-free certification. Brand selection links a checked model guide; it does not authenticate your installation or choose a lockout.
Calculation and input limits
Energy (kWh)= power (kW)× time (hours). Energy cost (USD)= energy× rate (USD/kWh). DOE explains that electricity use over time is measured in kilowatt-hours. The calculator applies this unit identity, not a heat-pump efficiency multiplier.
For a hypothetical constant-power example, 10 kW × USD 0.16/kWh × 1 hour = USD 1.60. Running at that same power and rate for 24 hours gives USD 38.40. Another example, 0.5 kW × USD 0.01/kWh × 24 hours, gives USD 0.12. The tool calculates the full product before rounding the displayed cost to cents.
The tool accepts 0.01–100 kW, 0–10 USD/kWh and 0–744 hours, with up to 2 decimals for power/time and 6 for rate. These are software input bounds, not equipment ratings or recommended runtime. Zero hours and a zero entered unit rate are accepted arithmetic scenarios, not free-heating claims.
Use the effective power/stages for the scenario. A nameplate may describe a maximum or a rating at a stated voltage; an Aux runtime is not proof that every strip stage ran continuously. If the rating is unknown, ask for documentation without opening a panel. Gas/oil or unknown backup is refused by the electric-strip calculator. Compressor, blower, fixed fees, other energy use and changes in tariff or duty cycle are excluded. For time-of-use rates or multiple stages, calculate each known segment separately; do not treat a single run as a forecast bill.
Manufacturer references
- ecobee Enhanced Setup and User guide (2023 PDF)
- Google Heat Pump Balance (live help)
- Honeywell Home T6 Pro Smart 33-00392 and T6 Pro II ISU table
- Honeywell Home T9 user guide 33-00478
- T10/T10+ Advanced Features and ISU table
- Daikin One+ unitary reference and aux heater setup
Documents were retrieved and relevant sections reread November 13, 2026. Paths and defaults are tied to the models/configurations cited; later firmware or revisions can differ. Other models and an unavailable earlier Nest configuration PDF are not silently treated as reviewed.
Independent guidance and safety
- DOE/BSESC controls and secondary heating
- DOE/BSESC heat-pump homeowner guide
- Trane not-heating guidance — manufacturer troubleshooting context, not an independent second experiment.
- CPSC home wiring hazards and USFA home-fire guidance
Illustrations and privacy
Four AIGC images depict generic equipment, labels and a winter setting. They are labeled generated; no image is a manufacturer screenshot, actual measurement, real installation, authentic nameplate or fault diagnosis. Code diagrams express the cited relationships and their limitations. Never use the fictional 10 kW plate as your equipment input.
Both tools run in the browser. This site sends no form answers, saves no answers and includes no analytics or external-font requests. Ordinary website asset requests still occur. No user account or paid diagnosis is offered. Examples are hypothetical; this site claims no field tests, user success rate or energy-saving percentage for your home.