Using ac setting to turn on heater?


Old 10-08-19, 02:38 PM
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Using ac setting to turn on heater?

I'm installing a new mr heater big max 50,000 btu in my garage and using a programmable thermostat I just replaced from in my house with a smart thermostat to operate it. I want to use the heat mode to run the heater 99.9% of the time with a garage door switch to shut heater off when the door is opened. I plan to use the switches below that pjmax recommended in an earlier post I found. My question is can I also hook up the ac mode to the heater so I can use it to run the heater to bypass the garage door switch the .01% time i need to? Thanks
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Old 10-08-19, 07:24 PM
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Welcome to the forums.

Yes..... you can use the magnetic switch on the heat (W) output of the thermostat and connect the heater directly to the cool (Y) terminal.

When using the cooling mode..... the Y connector will be energized when the temperature is over the set temperature. That's basically opposite of how you'd want a heater to work.
Old 10-09-19, 05:35 AM
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As said, heat will not operate when conected to the cooling terminal.
Also, you would need to connect the door switch in series with the heating function of the heater.
If the heater is operating when you open the door heating will stop but the fan will continue to run untill the heater cools down.
Don't connect the door switch to the fan circuit.

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