wiring up furnace for generator


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Old 04-18-06, 11:42 PM
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wiring up furnace for generator

ok, im sure I'll get abused here, but here goes...

I am thinking of wiring up my furnace for use with a generator in emergency situations.

The easiest and simplest way to avoid hooking up my generator to the house panel, would be to put an outlet on the furnace, and then run a heavy guage wired plug to that outlet. then, should I need to hook up to the generator for any long term power outage, I can 'unplug' the furnace, and plug it into a heavy duty cord (or permanent wiring) to my generator outside (about a 15' run) to the outside.

crazy? not to code? or ok for a couple days should an ice storm hit us country folk?
 
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Old 04-18-06, 11:56 PM
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Originally Posted by RpmQ
ok, im sure I'll get abused here
If you can dish it out, you should be able to take it.

> The easiest and simplest way to avoid hooking up my generator to the
> house panel

This just came up recently also.

http://forum.doityourself.com/showthread.php?t=260403

There was a good thread on this.
Perhaps someone else remembers it and can point it out.


> would be to put an outlet on the furnace

What's an outlet? Did you realize that you are talking about a cord and plug?


> I can 'unplug' the furnace
Nope.
 
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Old 04-19-06, 05:00 AM
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Originally Posted by RpmQ
ok, im sure I'll get abused here, but here goes...

I am thinking of wiring up my furnace for use with a generator in emergency situations.

The easiest and simplest way to avoid hooking up my generator to the house panel, would be to put an outlet on the furnace, and then run a heavy guage wired plug to that outlet. then, should I need to hook up to the generator for any long term power outage, I can 'unplug' the furnace, and plug it into a heavy duty cord (or permanent wiring) to my generator outside (about a 15' run) to the outside.

crazy? not to code? or ok for a couple days should an ice storm hit us country folk?
Rpm,
I don't know much about code but I think connecting a furnace with a plug into a receptacle is not a good idea!

I wouldn't take that chance because if there were to be a fire in your home; and your insurance company found out you have your furnace connected with an extension cord, they'd probably deny your claim even if the fire was unrelated!

I just finished installing an 8 circuit transfer panel and it didn't cost too much. Of course, I have an electrician in the family so I didn't have to pay the top dollar for that. The panel cost $150 and about another 100 bucks or so for everything else. I hardwired everything so all I have to do is plug in the generator with a pigtail to a receptacle in my garage, flip the interlock switch on the transfer panel and Iím good to go on generator power.

You could buy a smaller version like a 4-circuit transfer switch and run a cord from the generator to the switch. This type of set-up would only set you back about $100 or so and you could run four of your most important circuits.

Donít screw around with back feeding from your generatorÖ..Itís not that much work or expense to do it the right way!!!!!
Phil
 
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Old 04-19-06, 05:22 AM
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Actually, that's exactly how my old gas furnace was connected. There was a box in the furnace housing with two outlets, the fan plugged into one outlet, the transformer into the other. The one the fan was plugged into was controlled by the transformer. I could 'swap' the plugs and the fan would run all the time but of course the ac/heat didn't work then.

As long as it's gas, I see no reason why not, the fan and electronics don't pull signifactly more power than a large floor fan you'd use in a garage.

Obviously if it's electric, then the generator isn't going to supply enough power for the heating elements anyway.
 
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Old 04-19-06, 08:40 AM
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Originally Posted by Philossifer
I just finished installing an 8 circuit transfer panel and it didn't cost too much. Of course, I have an electrician in the family so I didn't have to pay the top dollar for that. The panel cost $150 and about another 100 bucks or so for everything else. I hardwired everything so all I have to do is plug in the generator with a pigtail to a receptacle in my garage, flip the interlock switch on the transfer panel and Iím good to go on generator power.
That's what I did.. Ran a 220 line to the garage from the main..
My garage circuit box has 6 breakers plus the dual 30amp for the generator.. I just shut off the house main, plug in the generator, fire it up, and throw the breaker on.. That way I can power up anything in the house, but mainly the fridge, furnace, well, couple lights, or even the coffee pot on my 4400 watts..
 
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Old 04-19-06, 08:48 AM
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Originally Posted by AxlMyk
That's what I did.. Ran a 220 line to the garage from the main..
My garage circuit box has 6 breakers plus the dual 30amp for the generator.. I just shut off the house main, plug in the generator, fire it up, and throw the breaker on.. That way I can power up anything in the house, but mainly the fridge, furnace, well, couple lights, or even the coffee pot on my 4400 watts..
Your installation sounds illegal and dangerous. There must be a mechanical way to ensure that the generator breaker and the main breaker cannot both be on at the same time.

Please change what you have. You are putting people at risk of death with your setup, and putting yourself at risk of going to jail should someone get hurt.
 
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Old 04-19-06, 09:02 AM
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Originally Posted by racraft
Your installation sounds illegal and dangerous. There must be a mechanical way to ensure that the generator breaker and the main breaker cannot both be on at the same time.

Please change what you have. You are putting people at risk of death with your setup, and putting yourself at risk of going to jail should someone get hurt.
racraft,
You know it amazes me that people would risk their biggest investment in thier lives (their home) by running extension cords to back-feed their electrical service panel.

They'll spend hundreds of thousands of dollars on the purchase of their home but won't spend the few hundred dollars it takes to properly and safely connect a generator.

I don't get it?
Phil
 
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Old 04-19-06, 09:19 AM
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Originally Posted by racraft
Your installation sounds illegal and dangerous. There must be a mechanical way to ensure that the generator breaker and the main breaker cannot both be on at the same time.

Please change what you have. You are putting people at risk of death with your setup, and putting yourself at risk of going to jail should someone get hurt.
How so? I did it exactly as the neighbor down the street hired a licensed electrician to do his.. I shut off the house main, then engage the garage gen. breaker.. Are you saying I should install the gen. plug in the back of the house, connected to the main panel?
 
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Old 04-19-06, 09:52 AM
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If your setup allows the main breaker to still be turned ON while the generator is backfeeding into the panel then your installation is illegal and extremely dangerous.
 
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Old 04-19-06, 10:56 AM
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Originally Posted by AxlMyk
How so? I did it exactly as the neighbor down the street hired a licensed electrician to do his.. I shut off the house main, then engage the garage gen. breaker.. Are you saying I should install the gen. plug in the back of the house, connected to the main panel?
Axl,
What he's saying is: you need a "Mechanical" interlock that disconnects the transfer panel from the utilitly service when you're on generator power.
See this pic:
http://www.electricgeneratorsdirect..../30050_400.jpg
The top two breakers are interlocked so that when one is on, the other cannot be on. Switch on the utility main, it shuts off the breakers to the generator....Switch on the generator, it shuts off the breakers to the utility main.
Phil
 

Last edited by Philossifer; 04-24-06 at 10:42 AM.
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Old 04-20-06, 08:39 PM
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Well, backfeeding is definately something I wanted to avoid, which is why i had come up with this rudimentary solution. I figured this idea wasn't to code, but took a chance asking anyways.

But thanks to bolides link, I found a single circuit transfer switch that I think I can use, and will safely isolate the furnace from the main, and it's much more affordable than some of the full blown solutions that are overkill for my application.

btw, yes, its a gas furnace, so all I'm running is the blower, and probably one receptacle for radio... we have everything else we need with gas.
 
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Old 04-20-06, 09:34 PM
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> it's a gas furnace

I am a believer in ventless gas heaters.
It's a controversial issue for some people. But these heaters don't require any electricity. I don't like freezing. Natural gas is pretty reliable.

Even a 10,000 BTU/hr unit makes a lot of heat because it is continuous.
A 60,000 furnace running for 15 minutes per hour makes about the same.
(As you can see, a 30,000 heater would match a small furnace that was running half the time.)

You can further cut the demand for electricity with such heaters. They also cut your gas bill because they are 99.9% efficient; whereas your furnace could be 80-93% efficient.

If the "unvented" part is an issue for you, there are non-power vented versions including wall furnaces that do not use electricity (but are not so efficient) and cost a lot more.
 
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Old 04-20-06, 09:48 PM
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Last edited by mattison; 04-21-06 at 08:14 AM.
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Old 04-20-06, 11:32 PM
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Last edited by mattison; 04-21-06 at 08:15 AM.
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Old 04-21-06, 04:36 AM
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Last edited by mattison; 04-21-06 at 08:15 AM.
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Old 04-21-06, 06:39 AM
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We got off on a tangent here with the ventless issue, which is a moot point for the millions of people who have forced air heat. Regardless of the burner, you still need to run the fan,
 
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Old 04-22-06, 07:49 PM
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Originally Posted by Philossifer
Axl,
What he's saying is you need a "Mechanical" interlock that automaticlly disconnects the generator (or a transfer panel) from the utilitly service.
See this pic:
http://www.electricgeneratorsdirect..../30050_400.jpg
The top two breakers are interlocked so that when one is on, the other cannot be on. Switch on the utility main, it shuts off the breakers to the generator....Switch on the generator, it shuts off the breakers to the utility main.
Phil
That is a manual interlock transfer, nothing automatic about it. As said, the nature of the mechanism prevents the Main and the Gen breaker from being closed.

Since AxlMyk's Genny breaker is on a subpanel in a totally separate part of the house than the main, it is plainly impossible for an interlock system to be installed, and therefore illegal.
 
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Old 04-24-06, 10:55 AM
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Originally Posted by classicsat
That is a manual interlock transfer, nothing automatic about it. As said, the nature of the mechanism prevents the Main and the Gen breaker from being closed.

Since AxlMyk's Genny breaker is on a subpanel in a totally separate part of the house than the main, it is plainly impossible for an interlock system to be installed, and therefore illegal.
classicsat,
Okay.....You got me on that one because I used the wrong "Word."

Yes, the transfer panel I mentioned is "Not" automatic and I did not intend for my post to mean it is an automatic transfer panel!

I used the word "AUTOMATIC" in the sense that when your index finger "Manually" flips the generator breaker to the on position, the energy from your index finger also pushes on the metal interlock which moves the utility breaker to its off position.

I wonder if you read my whole post or if you just read the word "Automatic" and then fired back at me? It sure seems like the later, because had you read the rest of my post, it would have been very clear that I was not talking about an "Automatic Transfer" switch!

Sheeeeesh, I guess you really gotta' be careful how you word things around here. What's next, are we going to be graded on spelling? (((LOL)))
Phil
 
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Old 04-24-06, 05:27 PM
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The biggest concern would be that the plug(s) and socket(s) be rated for the current/voltage.
Since you say "furnace" I assume you have an oil or gas furnace, and the only electrical requirement is for the control circuits and blower motor.
A safer alternative is to route the circuit for the furnace through a generator transfer panel. You can get them at a decent price at a home improvement store. These type of panels have an interlock that does not allow mains and generator breakers to be on at the same time. With one of these panels installed, you can also route other circuits you wish to run from the generator through the panel.
SQUARE D GENERATOR PANEL
You would still need a generator cord with appropriate plugs, but run it to the panel instead of directly to the furnace.
If you're REALLY motivated, you could run wire from the generator breaker on the panel to an outside 240v outlet of the appropriate amperage. From there you would only need a short cord with plugs on both ends for the generator. Then you wouldn't have a cord snaking through a door or window.
 
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Old 04-24-06, 09:26 PM
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240v outlet of the appropriate amperage. From there you would only need a short cord with plugs on both ends for the generator. Then you wouldn't have a cord snaking through a door or window.
Safety depends on how you define plugs and outlets. If you define all plugs as male and outlets as female then it would be dangerous.

The "240 V outlet" should be Male. The end that plugs in should be female. Some might read "short cord with plugs on both ends" as having male plugs on both ends but that would leave exposed metal blades on the "hot" end that plugs into the wall outlet. A potentially lethal situation if unplugged while still plugged into a running generator.
 
 

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