On my old (very simple) Miller furnace, I bought a marine battery and a 750 watt inverter. It didn't have enough power to run the blower motor. But, my generator did the job.
The inverter draws power even when turned off, so it killed the battery while I wasn't using it.
Necessary to actually try it out before depending on it for power cut. Might not work. Regular testing and maintenance.
Even if you manage to find one big enough to run the furnace the run time will probably be inadequate. If the power outage is short enough to get through with a battery powered system then you can probably get through without getting too cold.
Checking on it my unit is rated at 9 Amps. To run for
10 hours that would require 9 * 120 * 10 about 12 kWh of storage capacity. That is a pretty big battery, especially since that disregards inefficiencies in the system. Figure a safety factor of 50 percent and you will be talking about 20 kWh (all rough figures). For comparison my UPS' have ratings of something like 750 Watt hours, or .75 kWH.
In fact of course you may not need to run the heater that much, but if the power is going to be off for more than one day you would really need a big one.
IDK about the exact numbers, but agree with the overall principle. He could put an amp meter on his system to get the actual numbers. For the $425 you're in the range where you can get a generator. A generator makes more sense to me. If you have nat gas available, getting a generator that runs on it is perfect. There are conversion kits available for many generator engines that allow you to use nat gas, propane, or gas and switch between them.
IMHO you'd be much better off getting a small backup generator to power your furnace fan and electronic ignition for the furnace. Even an el cheapo from Harbor Fright or a small, used one from Craigslist will fit the bill.
A UPS will NOT economically deliver what you want. The run time would be just too short. Likewise, you're really only going to need this in a prolonged power outage. Unless you live in a tent in Maine, a two or three hour outage is likely to have very little impact on your comfort. OTOH, if you DID have a UPS in play, its energy would likely would be depleted in that same period of time and you'd be...
The backup generator will allow you to prevent loss of food, etc. should you lose power in the summer, etc.
IF the inverter will start the furnace, you have, at best, 3 hours of run time for your furnace, and most likely by the time the battery is down to 50% it won't START the furnace any more.
Even an inverter requires all of the transfer equipment/care that a generator does, and a twist-lock single outlet/plug for a furnace can be made code compliant and will allow you to unplug the furnace and direct connect it to a generator - or a 3 way switch can be used to "transfer" the furnace from the grid to the generator.
I'm putting a "motorsnorkel" conversion on my 7200 watt Champion generator and will have an interlock onmy new breaker panel when it is installed next spring.
Please do try it with the furnace. You may find out that your battery and inverter either do not work, or don't run very long. Nice to know before the power goes off for a week that you need a bigger power supply for the furnace.
There are also vented wall heaters for propane or NG, you might be able to buy NOW before it gets too much worse.
they need to be replaced every 3 years. about $60 each. Vs the gasoline and upkeep on a generator. gasoline clogs fuel lines and has to be fussed with to keep working
The Xantrex-802-1500 is not a UPS. I can not be plugged in (charging) while it is discharging. One of the other.
The Xantrex-802-1500
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Product Specifications
120 Vac AC output power (continuous): 1350 W AC output surge capacity (peak): 3000 W AC output voltage: 120 Vac AC output frequency: 60 Hz AC output waveform: Modified Sine Wave
But a battery has a VERY limited capacity 100AH out of a 60 lb lump
- while a generator keeps providing power as long as you can feed it. Having a battery and inverter for low power short term loads to avaid running the generator full time can make sense - as long as the battery is charged by the generator when the generator is running.
A UPS will only run the furnace a relatively short time and if the power is only out for a short time, the temperature in the house won't drop much. A back up generator is the way to go and should be used with an automatic transfer switch. A small UPS could be used to hold power until the generator kicked in, but would not be necessary unless there is medical life support equipment (which should be on a UPS anyway)
Further note:
For anyone here who does have a UPS and the battery is on float charge, it is important that you use the more expensive VRLA battery . (Valve regulated Lead Acid)
It is designed to NOT emit hydrogen. If you use a standard "wet" type car or marine battery indoors, there is a potential explosion hazard!
What are the actual odds? How many exploding batteries really happen?
The only time in my life I've known of an exploding battery was when an old farmer was using 12 volt boost setting on a car battery. I could smell the acid, and I was on the other side of the machine from the battery. He leaned over and wiggled the cable clamps on the post. It sounded a bit like a short barrel revolver shot. "Get some water for my eyes" he said.
I considered this for my furnace, but decided a generator would be more cost effective for the few times the power goes out for periods longer than the thermal time constant of the house. The batteries won't run that long anyway.
What happens when the batteries are low, the furnace kicks on and preheats...later, the air handler starts, dropping the battery voltage below the cutout threshold and shuts it down...until it restarts. I just don't like gas on fire in the midst of electronics that's surging on and off. Sure, it's all protected so that can never happen. Until it does. YMMV
My experience is that the gas valve and ignitor (well, my old furnace had pilot light) were fine. The air handler blower would not power. So, all that heat and no where to blow with it. That didn't seem safe.
I did get a two stroke ETQ generator. it doesn't start very well, needs ether if it's been sitting. But, the generator provides a few hours of run time. An hour of furnace before bed time is enough to keep the place over night. Let the generator cool, and bring it indoors. Less likely to be stolen.
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