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kodak_jack
Running 95% furnace on a Generator
kodak_jack

Our area just went through a wind storm that left us without power for 4 days. I have a 2003 Troy-Bilt 5500 generator (model 01919), but didn't dare plug my furnace into it for fear of blowing the control board with "dirty power". The electronics on most appliances are very sensitive. Isn't there any way to clean up the output of my generator so it will run my furnace? I would hate to have to buy a second inverter generator so I have to maintain and run two. A 2400 watt inverter generator is around $1,000, just for that one circuit. If I go to the heating and cooling contractor, they want to sell me a mega buck whole house generator. I accept that, in an outage, I do not have to power my entire house. I am only concerned with that one circuit. When the furnace was installed, I told them I wanted it capable of running off of a generator, so, they installed a switch to isolate it from the panel box (no feedback to the grid) and left me a pigtail so I could plug in my generator. When asked about the vulnerability of the board, the installer said to just make sure the generator was up to speed before switching over. I have asked many people who are "in the know" and I get a different answer from each one. What about a power conditioner? Another suggestion is an uninterrupted power supply. I can't imagine what one that is big enough for 2400watts would be!
I cannot find a useful sticker anywhere on the outside of my furnace. It is a 2010 Rheem 95% at about 80,000 BTU's.

Jack
Re: Running 95% furnace on a Generator
Jack

1- if you use a generator you must make sure it is grounded to your grounding system, the furnace requires a ground for the flame sensor to work properly.
2-A generator should not be a problem because the 120 volt in feeds a transformer that steps it down to 24 volts which is the voltage required bu the control board. While the blower, fan and ignitor use 120 volts they will run on dirty power.

Jack
P.S. I've run my furnace several times with my 5500 watt generator.

kodak_jack
Re: Running 95% furnace on a Generator
kodak_jack
JLMCDANIEL wrote:

1- if you use a generator you must make sure it is grounded to your grounding system, the furnace requires a ground for the flame sensor to work properly.
2-A generator should not be a problem because the 120 volt in feeds a transformer that steps it down to 24 volts which is the voltage required bu the control board. While the blower, fan and ignitor use 120 volts they will run on dirty power.

Jack
P.S. I've run my furnace several times with my 5500 watt generator.

From a twist lock connector on the generator, I go to a twist lock receptacle on my house. From there, I have it go into my basement where another twist lock receptacle allows me to plug in a cable that came with the generator that gives me four 120VAC outlets. I've essentially eliminated having to have a door open with extension chords running inside. One of the outlets I would use to power the furnace. The furnace installer gave me a switch to isolate the furnace from the panel box and a pigtail for the generator to plug into. If I need a ground, where and how would I hook that up considering what I have? The generator has a ground lug, but I think it's to prevent a shock to me from the generator while being around it, right?

Jack
Re: Running 95% furnace on a Generator
Jack

The twist lock plug should have 4 prongs, L1, L2, Common, and ground. The cable should be 4 conductors. When you go to 120 outlets you just have to make sure that the hot, neutral and ground are included.

You can pick up a circuit tester like below to test the outlets.

Jack

kodak_jack
Re: Running 95% furnace on a Generator
kodak_jack
JLMCDANIEL wrote:

The twist lock plug should have 4 prongs, L1, L2, Common, and ground. The cable should be 4 conductors. When you go to 120 outlets you just have to make sure that the hot, neutral and ground are included.

You can pick up a circuit tester like below to test the outlets.

Jack

Yes, there are 4 wires. I'll have to pick one of those up.

Marc
Re: Running 95% furnace on a Generator
Marc

I just had a manual transfer switch installed in basement. When testing with generator (7000w continuous) to run furnace (and other essentials), the furnace sounded much like a car whose battery was weak...and wouldn't "kick over." Reading online comments, it seems that the neutral of my generator may not be bonded correctly to its frame. I also did not ground the generator from its lug. I just drove a ground rod 4 feet into ground and attached to gen via 6gauge ground wire. Should this solve the problem or will I need an AC line conditioner? Any insight will be helpful. Thanks.

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