How much does a gas furnace cost to run?
About 7.9p an hour in the UK and 5.5¢ an hour in the US. A gas furnace draws about 600 W for roughly 50% of the time it is switched on, so it averages 300 W. The gas makes the heat, but the blower that pushes warm air through the ducts is a real motor with a real start-up surge — far more than a British combi boiler. Variable-speed (ECM) blowers usually draw less.
What it costs, by how long it runs
| Running for | kWh | UK | US |
|---|---|---|---|
| 10 minutes | 0.05 | 1.3p | 0.92¢ |
| An hour | 0.3 | 7.9p | 5.5¢ |
| An 8-hour night | 2.4 | 63p | 44¢ |
| A full day (24 hours) | 7.2 | £1.90 | $1.32 |
| A month at 8 hours a day | 72 | £18.95 | $13.20 |
UK prices use the Ofgem price cap for 1 October to 31 December 2026 (direct debit, average across England, Scotland and Wales, with no VAT on electricity this winter): 26.32p per kWh (Ofgem). The standing charge of 54.83p a day is paid whatever you run, so it is left out. US prices use the US average residential price for June 2026 from the Energy Information Administration: 18.34¢ per kWh (EIA). Your own tariff is on your bill; scale the figures by it.
Measure your own
These are typical figures for a typical unit. A plug-in energy monitor between the socket and the appliance shows the real watts and adds up the kWh, so after a day or a week you know exactly what it costs on your tariff.
Compared with similar appliances
| Appliance | Average W | UK per hour | US per hour |
|---|---|---|---|
| Electric blanket | 21 | 0.55p | 0.39¢ |
| Heated throw | 40 | 1.1p | 0.73¢ |
| Gas combi boiler (its electrics) | 51 | 1.3p | 0.94¢ |
| Gas furnace (blower and controls) | 300 | 7.9p | 5.5¢ |
| Space heater, 750 W | 750 | 20p | 14¢ |
| Oil-filled radiator | 900 | 24p | 17¢ |
| Space heater, 1,500 W | 1,500 | 39p | 28¢ |
| Space heater, 2,000 W | 2,000 | 53p | 37¢ |
| Fan heater | 2,000 | 53p | 28¢ |
Running it in a power cut
See which power station will run a gas furnace, and for how long.
Appliance draw modelled on www.shareddocs.com. Carrier’s product data for the 58SB 80% furnace lists maximum unit current of 5.6 to 13.4 A at 115 V (roughly 640 to 1,540 W) with direct-drive blowers of 1/3 to 1 hp. Those are maximum ratings; 600 W is a typical running figure for a mid-sized blower at heating speed plus the inducer and controls, and the 1,500 W surge is an estimate of a blower motor starting.
Did this match what you measured?
Nothing is sent anywhere unless analytics is switched on, and no text is collected.