Instapundit, musing about running your furnace off a 1500VA UPS: "Yeah, though I suppose you could run it for a while on a big UPS. A furnace fan doesn’t draw that much power. And even running the furnace for half an hour and re-warming the house would sure be nice if the alternative was nothing."
Good luck with that. A 1/4 HP 120V motor pulls around 6A, or 720 watts. And that's just the running amperage. If you got five minutes out of a 1500VA UPS I would be surprised, especially given that the larger furnaces these days often have 1/3 HP motors. Plus you're powering a transformer that operates the gas valve, and if you have a modern furnace you're running another transformer that heats a glow plug to light the pilot light...and we're still assuming you're talking about a gas furnace and not a heat pump or an electric furnace, in which case, why are you bothering?
During a long power outage a few years ago, I tried to use a 1500VA UPS to open the garage door. It didn't even budge. The startup draw was so heavy it drained the battery straight away.
A gasoline generator is what you want. Live with it.
If you are going to write in a foreign language I am not even going to bother.
ああ、あなたが理解できないのですか？
Actually, the very best deal is a gas generator. They make them with auto start and all kinds of goodies, and as natural gas service (At least around here) is 10 times as reliable as electricity, it's a good bet you won't even know it's running. Until you get the gas bill, that is.
A natural gas generator is great if your line from the street is big enough to run it and your furnace at the same time.
My understanding is that in some cases the gas company has to run a bigger line to feed both units.
I keep looking at them but I can buy a lot of 5K gasoline generators for the $10K it would cost to get a natural gas one installed.