Gas heat still needs electricity
A gas or propane furnace burns fuel for heat, but its blower fan, igniter and controls run on electricity. Without power the furnace won’t start, and heating with a gas oven or stovetop instead is dangerous.[1] The blower motor is the part to size for.
Furnaces are hardwired, so connecting one to a generator takes a transfer switch or interlock installed by a qualified electrician.[2]
Furnace fan plus the rest of the house
Motors don’t all start in the same second, so you only add the single biggest startup jump on top of everything that’s running.
- Furnace fan + fridge + lights: 1,675 W running, 3,950 W starting → at least 2,094 W rated (mid portable). Open in calculator
We divide the running load by 0.8 because a generator shouldn’t sit above about 80% of its rating for hours.
Questions
Can a generator run an electric furnace?
An all-electric furnace or heat strips draw far more than a gas furnace’s blower — usually a home standby job. Check the furnace label.
Will an inverter generator protect the furnace controls?
Inverter generators produce clean power that’s gentle on electronic boards, which is one reason they’re popular for furnaces.