Generator to gas furnace

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Old 01-21-16, 10:04 PM
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Generator to gas furnace

We have a blizzard coming and I already had one burst heating pipe this season and would like to make sure I have heat if I lose power.

I've got a portable generator and I'm thinking it should be easy to build a simple device that switches the gas furnace electric line from house power to an extension cord that plugs into the generator.

I've got hydronic heat so the power is mostly for the circulator pumps and the blower in my high efficiency boiler. Some rough calls and I think I'm at 12A if everything is running - which they won't.

I've got the furnace line and control box running to what looks like a small circuit breaker - of maybe it's just a heavy duty on-off switch. That box has a line from the panel.

So....is this as easy as wiring a box with a DPDT 20A switch and connecting a cut off extension cord to one side and my line from the panel to the other? If I want to switch to the generator I throw the switch and plug the male coming off my new switch box into an extension cord I run to the generator outside?

Any risk the switch could fail someday and then the male connection coming off the box is hot? And do I just connect all ground wires together?

Anything else I got to worry about? Part of me wants to just build a plug off the furnace box and install a regular wall outlet. Then if I need to use the generator I just unplug it from the wall into the generator via an extension cord.

Thoughts?
 
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Old 01-21-16, 10:40 PM
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Any risk the switch could fail someday and then the male connection coming off the box is hot? And do I just connect all ground wires together?
Sure the switch could fail. Anything can fail. The grounds would get connected.

I'm not a big fan of putting the heating system on a plug and receptacle but you do what you need to do in a storm situation.

They make a transfer switch just for what you are doing.
Reliance Controls Furnace Transfer Switch-TF151 - The Home Depot
 
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Old 01-22-16, 02:39 AM
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You do not want to use a cord with two male ends. They are called suicide cords.
 
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Old 01-22-16, 03:08 AM
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Who wrote anything about a cord with two male ends?

The OP asked about installing a (female) receptacle on the fixed wiring and then using a flexible cord with a male plug from the furnace. Then he could use a standard extension cord from the generator, remove the plug from the receptacle and plug the furnace into the extension cord.

While technically a violation of the NEC I understand that somewhere ( I think it was even in Arizona or perhaps New Mexico) this method IS allowable and not at all uncommon.
 
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Old 01-22-16, 06:33 AM
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I would go with a double pole double throw switch (common terminals connected to the furnace leads) and wall mounted male receptacle (instead of a hanging cord and plug). This is the equivalent of a standard generator transfer switch although for much lower amperage compared with a whole house transfer switch.

Yes, you connect all incoming ground wires together in each box. Together with jumpers (pigtails) to switches and receptacles in the box and to the box itself if metal.

.
 
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Old 01-22-16, 11:48 AM
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The OP asked about installing a (female) receptacle on the fixed wiring and then using a flexible cord with a male plug from the furnace.
Furd, the way I understood the OP was that the cord with male plug would be wired to one side of the DPDT switch and the existing circuit wired to the other side of the DPDT switch. It would work, but isn't in my mind a safe way to do it. I'd substitute a male power inlet for the cord with male plug.

Actually, I wouldn't di it this way at all, I'd opt for the Reliance single circuit transfer switch that PJ linked to. This way there wouldn't be any chance of a future home inspection being failed.

I've got hydronic heat so the power is mostly for the circulator pumps and the blower in my high efficiency boiler.
Now, tell us about the furnace you want to get power to.
 
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