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wiring an attic fan in parallel

Posted by reed_nj (My Page) on
Sun, Oct 2, 11 at 19:59

I'd like to wire a new attic gable vent fan so I can turn it on and off from a switch downstairs, but still allow the attached thermostat to operate the fan as well. The added downstairs switch must be wired in parallel to the thermostat, but do you simply connect all the black wires together and whites together at the thermostat, or do you connect the black wire from the new switch directly to the fan motor, thus bypassing the thermostat?

Follow-Up Postings:

RE: wiring an attic fan in parallel

Hello reed_nj

This is one way to do it, Power goes to the fan first..If the thermostat
calls for power, your new switch will not shut off the fan..


Hope this helps

Let us know how you made out with your wiring project

Have A Nice Day

RE: wiring an attic fan in parallel

Thanks Linesman. Diagram makes sense, although not sure if the wiring at the fan is accessible. I'm getting the fan tomorrow, but I think between the fan and the thermostat the wires are in a flexible conduit. If the wires are only exposed at the thermostat, is there still a way to wire it up parallel?

RE: wiring an attic fan in parallel

If you look at the diagram again you will see two wires added to the thermostat that run to the new switch. You should only add the wires at the thermostat.

RE: wiring an attic fan in parallel

OK...I see that. And the two wires from the power source go to the fan? If so, not sure where they would connect to due to the conduit.

RE: wiring an attic fan in parallel

Is your purpose to be able to turn on the fan without the thermostat? Or is it to energize the fan and let the thermostat do what it was designed to do?

RE: wiring an attic fan in parallel

The latter....allow the thermostat to control the fan when temps get high enough, but also I want to be able to turn the fan on at any time.

RE: wiring an attic fan in parallel

Received the fan today and it answered my question. Inside the thermostat housing, the wiring setup allows for connections both before AND after the thermostat. This will allow me to connect the extra wire from the new switch to the thermostat wire that's "downcurrent" of the thermostat switch.

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