furnace runs on backup power directly, but not through main panel

[dtiemeyer]

I just bought a LPG generator from the local big-box chain, it only has two 120v 'plugs', there is no 240v. I have fabricated an adapter cord with 2 male ends (10ga wire, 20a ends) to connect the generator to the house - there is a 20a rated wire and breaker I am backfeeding into. With the main off, I am leaving ON only the breaker of the circuit that I'm plugging the generator into and the breaker of the furnace. Both are on the left side of the panel. When I backfeed through a plug into my main panel in this condition, all my lights will work, refrigerator, etc, everything but the 95% Goodman furnace which will not turn on the fan nor ignite.

My furnace has a receptacle and switch mounted to it. And the receptacle is upstream of the switch, meaning the switch does not toggle on/off the receptacle, only the furnace downstream of it. When I plug the generator directly into this plug (and leave the switch on, of course) the furnace runs beautifully.

Ideally I would like the furnace to run while the entire house is backfed, but I dont understand why the furnace runs when fed directly by the generator, but not by the generator through the house main panel.

Its a 4000w generator, and the furnace fan only draws 8A at startup (less while running), so I dont think the problem is related to load.

Thank you for any insight. And yes, I realize that I could injure myself, and that I should have a disconnect.
Dustin

[buford]

+The way you are doing that you are only energizing half of the panel. I am sure there is other things that do not work also. You should get a transfer switch put in to protect your house and to protect from feeding back down the utilities line. The way you are doing it is not safe for you or your neighbors if you forget to turn off the main!!!

[dtiemeyer]

I know I'm powering only half the panel, that's why I pointed out that both the back feed breaker and furnace breaker are on the same side of the panel.
And I know the dangers, that's why I mentioned turning off the main during backup supply situations. Do you have any constructive thoughts?

[jnaas2]

Just because the breakers are on the same side doesnt mean that its the same phase, As you come down one side they change which phase they are on. To get both breakers on the same phase they must be on a 1, 3, 5, 7, etc or 2, 4, 6, 8, etc. What dtiemeyer says is correct, He was giving you constructive thought, If you forget to turn off your main breaker what will happen, this is a test, there are reasons for generator transfer switches because what you are doing could get someone killed if someone forgets

[jnaas2]

One other thing I forgot, Cheap generators produce a square sign wave and they are usually very dirty and some computers and other equipment dont like this dirty power and this can damage the equipment and burn up circuit boards

[buford]

According to your profile, this should be easy to do for you. sounds like a DIY to me. You have more than enough info to figure this out.

[dtiemeyer]

Gentlemen, thank you. And my apologies to buford, with the help of jnasas2's more concise answer, I now realize you *we're* pointing me in the right direction and providing constructive feedback, whereas upon first reading your response it seemed only like you were telling me I was wrong about the panel being powered, then scolding me for something I already knew was wrong and admitted as much so.

It turns out that getting the furnace breaker onto the same 'leg' as the incoming generator power breaker did the trick. And turning off the 240v breakers in the panel helped too, I think.

Next step, disconnect switch

[DavidDeBord]

What brand of LP Generator did you pick up atr the "Big box store"? And, hopefully, by now, you've gotten the transfer switch, & some form of disconnect between the Generator, & your panel.

[dtiemeyer]

It was the Sportsman 4000w/3250w model from the 'orange' colored big-box store. It also happens to be on sale for $300 right now ($320 for CA). It has been great, although I haven't had much need for it, but I start it every couple months, and it always starts on within 3 pulls. For that price you can get a disconnect and at least 1 filled 25 pound propane can and have it all done for less than $500. Just remember it's only 120v. It wont push your electric stove/ac/dryer. But it meets my needs for my little 750sqft house just fine.

[DavidDeBord]

Sir,
Have you looked into the possibility of installing a larger generator, such as a 8KW, or even a 17KW? I ask this because units of that size would safely meet your Primary needs, & a unit possibly even smaller than 17 KW would power your entire home.

[dtiemeyer]

3250w (27amps) does run my whole house, in fact, every light and appliance in my house together add up to less than 25amps. My range and dryer are both gas, and I dont have AC. This generator will power everything I own (never mind 75% of it is not on at the same time) and it will run almost 24 hours on 1 can of propane. Now if you have a big house, or power-hungry kids, or 240v appliances, it may not be the right solution for you. But it works like a charm for me.

[DavidDeBord]

Excuse me Sir. I'm looking at your situation from not only the practical view point, but from what is safe, what will meet the NEC Code minimum requirements, & what will satisfy your Insurance company, "if", any problems do arise where you might need their help.
It doesn't matter what "the right solution for me", would be, as I don't live there, it's not work that I performed, nor would I, unless it was a matter of Life & death. You've taken a unit, & greatly stepped outside of the parameters that it was designed for, & installed it in such a manner, that "if" you forget the sequence of operation that you have set up, then the result could be harm to Life &/or property, ..., let alone, getting into some very serious trouble with your Utility Provider, & the local Authorities.
Carry on Sir, You've got it all together, ..., in your eyes.

[dtiemeyer]

Why did you even bother asking me what brand of generator it was if you only ever intended to chastise me for the setup you *assume* I still have in place? Why not just get on with it from the get go? Troll...