7500 W Garage Heater Thermostat


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Old 01-25-22, 01:56 PM
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7500 W Garage Heater Thermostat

Hello All,

I have a question about wiring a external thermostat on a garage heater. I picked up some great info from this post: Garage heater Thermostat but still have some questions.

The goal is to be able to remotely turn on my heater a few hours before I get to the garage as it is uninsulated and takes a few hours to warm up. I currently have the heater hard wired to a 40amp breaker using stranded #8 copper. I would like to be able to use a standard 24v wifi thermostat so I can turn the heater on and monitor the temperature when I am not at the garage.

I can't seem to get the diagram to add to this post but here is a link to it (page 8):
https://hw.menardc.com/main/items/me...HP-6354251.pdf

My question is if I can I use a relay something like this:
https://www.amazon.com/gp/product/B0...qh_dp_hza?th=1
wired to the 1/2 connection of the external thermostat loop to allow for a 24v thermostat.

What I can't figure out is how much power Is running through the external thermostat loop. Is it just the L1 leg? Will the 240v/20 amp rating of the relay be adequate or do I need to try and find a 40amp relay?

I also considered using a relay to break L1/L2 before the thermostat but can't seem to find a 40 amp relay.

Thank you for your help,
-Kevin





 
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Old 01-25-22, 02:35 PM
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Update, photos attached.

Update:

Here is an internal shot of the heater and the diagram:



 
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Old 01-25-22, 03:16 PM
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Welcome to the forums.

You need to make sure the two power connections are labeled L1 and L2 and that the external thermostat terminals are labeled 1 and 2. Since you are dealing with 240v we don't want to get anything backwards. The colors shown for inside the heaters are arbitrary and are for discussion only. The three wires from the Aube RC840T-240 are the actual colors of the module.

 

Last edited by PJmax; 01-25-22 at 04:04 PM.
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Old 01-25-22, 03:31 PM
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Thanks Pete! Much appreciated.
 
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Old 01-25-22, 04:05 PM
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My post is updated with diagram.
 
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Old 01-25-22, 04:36 PM
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Amazing Thanks, I am really glad I asked. Just to clarify the blue wire on the Aube RC840T-240 should be making contact with the hot wire coming in at the terminal at L2? And just to double check I am good with the 22 amp rating of the Aube RC840T-240?
 
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Old 01-25-22, 04:42 PM
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Yes.... the blue needs a connection to L2.

The external thermostat connection is for remote control of the contactor inside the heater.
So it only needs to switch approx 1A. (fan and contactor coil)

As the thermostat cycles.... you will hear the contactor operate.
 
 

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