How Long Will It Run

Can a power station run your gas furnace in a power outage?

A gas furnace burns gas, but it cannot heat the house without electricity. The inducer fan clears the flue, the igniter lights the burner, the controls watch the flame, and above all the blower pushes warm air through the ducts. When the power goes out, the furnace stops, even with a full gas supply.

The blower is the problem for a battery. Carrier's product data for its 58SB furnaces lists a maximum unit current of 5.6 to 13.4 amps at 115 V, roughly 640 to 1,540 W, with blower motors from 1/3 to 1 horsepower. This site models a typical furnace at 600 W while running and 1,500 W for a moment as the blower starts. Of the 80 stations in the catalogue, 58 can start it.

Size a station for your furnace The cheap outage kit

How long it would run

Modelled for the blower running about 50% of the time, as it does on a cold day. A milder day, a lower thermostat setting or a variable-speed (ECM) blower all stretch it further.

StationCapacityFurnace alone, from full
Jackery Explorer 300 Plus288 WhCannot start the blower
EcoFlow DELTA 3 Plus1,024 Wh2 h 23 min
Bluetti AC1801,152 Wh2 h 41 min
Jackery Explorer 2000 Plus2,042 Wh4 h 44 min
Anker SOLIX F38003,840 Wh8 h 47 min
EcoFlow DELTA Pro 34,096 Wh9 h 18 min

For comparison, an Anker SOLIX C1000 runs a British combi boiler, which only needs a small pump and fan, for about 12 h 23 min, but a furnace for about 2 h 28 min. Ducted warm air costs far more electricity than hot water in pipes.

Problem one: the furnace is hard-wired

Most furnaces are wired to a dedicated circuit with a service switch beside the unit, not plugged in. The safe ways to run one from a power station or generator are a transfer switch or a furnace power inlet fitted by a licensed electrician, which disconnects the furnace from the utility before connecting the backup source. Do not cut the cable and add a plug yourself, and never back-feed a house circuit through a wall outlet: it can kill a line worker restoring power.

Problem two: the furnace may not light

Modern furnaces confirm the flame with a flame sensor that passes a tiny current through the flame to ground. In a house, neutral is bonded to ground at the panel. Many portable power stations have a floating neutral, and some furnaces then fail to see the flame, shut down after a few seconds and flash a flame-sense fault. Whether yours does depends on the furnace. An electrician can advise on the right connection; ask the furnace manufacturer or your HVAC contractor before an outage, and test it on a calm day.

Problem three: clean power and the start-up surge

Furnace control boards expect a pure sine wave, which lithium power stations generally provide; check the specification. The blower's start-up surge is why a station needs both enough continuous watts and enough surge headroom, not just a big battery. The runtime pages linked above run that check for each station.

If the furnace cannot run