with a very small generator or battery - but you can't run a heat pump on a generator without going with a much bigger one, (and much more expensive one).

My furnace's air handler fan pulls hundreds of watts. That's generator territory. And I'd have to re-wire it somehow to give it a male plug or better yet add a transfer switch.

A gas-fired boiler with radiant heat needs very little power for its fans and pumps.

I wish residential-sized gas-fired cogeneration systems were a thing.

My forced air heater was noisy and getting old. I installed a "Direct Vent" heater near the stairs in the basement and it keeps the whole house warm via natural convection. No electricity needed. You get to watch the cheery flame in the window, it is great.

I was worried the bedrooms would get too cold when the doors were closed but it turned out not to be an issue. The bedrooms do get colder but this actually is better for sleeping.

We still have the forced air system as a backup.

https://wildoaktrail.com/collections/martin-heaters