Power your furnace with an Inverter during a power outage – part 2

Frequent power outages left me concerned my furnace would be damaged while running. Brown outs, gradual black outs, over voltage, high and low frequency from tree’s on power lines in the City of Woodburn Oregon. And power outages that lasted hours typically. All this goes into our furnace and will gradually wear out the electronics, heat exchanger and more.

It is important to me to keep my family warm during power outages. Some heating the home options are better than others. Roughing it with lots of clothing, and a tent on the bed may get you by, but it won’t keep your pipes from freezing in your home.

Part 1 of this guide is here.

In February 2021 Valentines day weekend, we had an Ice Storm that took the utilities away from us for 5 days. No power.

I use an AIM’s 2500 watt inverter as a UPS power backup for my Rheem high efficiency hybrid furnace. Back in October 2018 I purchased the Inverter, and 5 AGM batteries as an experiment as a UPS for heating the house.

Disclaimer: I’m a DIY’er, AC and DC voltage can be dangerous, hire a professional to install a system like this.

Some of the technical details around this system;

  • The furnace is rated for a 3000 square foot home. It supports natural gas for emergency heat, as well as a Heat Pump for heating and cooling.
  • The furnace emergency heat runs off of 120 volts @ 20 amp circuit inside the home, which is independent of the Heat Pump which has its own dedicated 240 volts @ 45 amp circuit breaker outside the house.
  • The AIMS 2500 watt inverter has a 30 amp input, with a built in AC inverter output breaker at 20 amps. The breaker to the inverter is on a 20 Amp breaker. This makes it so I have to dial down the charger to be slower.
  • The AGM Battery bank is 100 Amps x 5 batteries = 500 Amp Hours. Or 6,000 watts total capacity before they are 0% DoD and damaged.
  • In the 2021 storm, the AGM batteries went to dead, due to generator issues that were designed to recharge it daily. (I thought it would last 2 days actually, it would have had it got above 45 F outside. For the 4 days the temperature was 32F and below).
  • The combination Battery Bank, and Inverter lasted 23 hours before they were dead.
  • I had multiple charging solutions, and only one inherited old and small 1600 watt (starting) 1000 watt running Coleman Generator.
  • All my RC charging solutions failed at anything more than 5-10 amps per hour charge rate on this generator.
  • The 240 volt 3500 watt contractor generator I purchased in 2018 ended up dead even with starter fluid spray. This was the chosen solution to recharge the batteries, as well as run the furnace and power some stuff in the home. = Failed. Read >> Here about the solutions my dad (Electrical Engineer) showed me<<

Some things to know before a storm or extended power outage;

  • How to fix and have the tools to repair a clogged carburetor.
  • How to ‘hack’ a generator to get it running with starter fluid. (See this page)
  • Have bypasses for generators that fail, and other options to get your heat up.
    • We have a pellet stove that is 120 volts, and can run from a smaller generator.
    • We have a Mr Heater camping heater that will help us heat a small room.

Things I wish I had;

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Bill Thompson

I am a mobile smartphone and embedded Linux engineer. I love to tinker with electronics and fly drones in spare time when not geeking out in a developers world!