Power station for a gas furnace blower: size and runtime
A gas furnace makes heat with gas, but its blower fan, control board and igniter need mains power. In a winter outage the furnace will not run without electricity. The load is modest compared with electric heat, but the blower motor has a start-up surge.
Typical numbers
| Item | Typical running | Typical start-up surge | Per day |
|---|---|---|---|
| Gas furnace blower, board and igniter | 500 W | about 1,500 W | about 3,600 Wh |
Typical values, assuming the blower runs about 30% of the time on a cold day. Variable-speed (ECM) blowers often draw far less; the nameplate on your furnace gives amps. Watts are roughly amps × 120.
Worked example
500 W × 24 h × 0.30 = 3,600 Wh a day, or about 150 W on average. With 85% of rated capacity usable:
| Battery rating | Usable | Furnace runtime |
|---|---|---|
| 1,000 Wh | 850 Wh | about 6 hours |
| 2,000 Wh | 1,700 Wh | about 11 hours |
| 3,000 Wh | 2,550 Wh | about 17 hours |
Good to know
- Check the station's surge rating against about 1,500 W (older PSC blowers); an ECM blower usually starts far gentler.
- Most furnaces are hardwired, not plugged in. Powering one from a station or generator needs a properly installed inlet with an interlock or transfer switch, or a dedicated furnace plug installed by a licensed electrician. Never back-feed a panel with a cord. Local amendments apply and a permit may be required.
- Do not add an electric space heater to the same station: 1,500 W empties a 2 kWh station in about an hour. Never run fuel-burning heaters or generators indoors; carbon monoxide kills.
- If you also need the fridge and Wi-Fi, build the combined load in the calculator's "Winter: furnace fan and fridge" preset.
Open the calculator with a furnace blower filled in
Appliance figures are typical values, not measurements of your device: the label or a plug-in watt meter on yours wins. The sums assume 85% of a battery's rated capacity reaches your outlets (how the numbers work). We list no prices and have not hands-on tested any product.
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