# Control Window Unit Air Conditioner With Thermostat?



## Tommy Plumb (Oct 7, 2006)

I have a 120v window unit and I was wondering how feasible it would be to wire it into a wall thermostat. My first though was to use a 120v Taco switching relay made for a boiler but that won't take the amperage and I'd have a big relay box to stare at. 

My second though was to add an outlet by the air conditioner. Then I'd use a line voltage thermostat to control the neutral. I don't really see any problem with that.


Next question. I'd like to do the same with a 220v unit and use an existing 24v thermostat that currently controls the heat. The thermostat does have a cooling feature on it that is currently unused. 

My thought here is I'd need some sort of enclosure which I could mount on the wall in my unfinished basement below the unit. The wire to the outlet for it is pretty easy to get to. I'd cut the wire and run both ends into the enclosure. The neutral would get spliced together and be un-switched. I'd need to find a double pole relay and run both hots to it. Then I'd have to find somewhere nearby I could put a 24v transformer. Then I'd run 24v into the box and into the relay using the thermostat to switch a side of it. 


Is this practical or safe? Any recommendations on parts, specifically what relay and enclosure I'd need?


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## Bud Cline (Mar 12, 2006)

> I have a 120v window unit and I was wondering how feasible it would be to wire it into a wall thermostat.


What's wrong with the internal thermostat it already has?


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## Code05 (May 24, 2009)

Tmb9862 said:


> My second though was to add an outlet by the air conditioner. Then I'd use a line voltage thermostat to control the neutral. I don't really see any problem with that.


I do, switching a neutral only is illegal.


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## Missouri Bound (Apr 9, 2011)

Switching an outlet would work (but not the neutral...that's a no no) if you want simply on and off. Most window air conditioners are designed to run the fan after the internal thermostat is satisfied. This allows a more even room temperature by keeping the circulating fan running at all times. You could switch the whole unit off and on with an outlet controlled by a line voltage thermostat.


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## josall (May 7, 2011)

What are you tryiing to accomplish?


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## biggles (Jan 1, 2008)

you can wire in a line voltage thermostat just disconnect the exsisting stat pair of wires and run them out to the location of the new stat.....check the ratings on that new stat from the unit tag totals..that 220v unit you might be able to sneek a relay inside the control area behind the dials..the amp rating will be lower then that 115V unit with the 3220V..and you only need to break one leg to shut it off.get a 24V relay and run R and Y1 to the coil on it...from the subbase...and on the N.O. contacts wire in one side of that 220V might be the same as that 115V just bring the stat wires over


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