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------ Update ------

I followed the instructions from Casa: I made A1 go into the new thermostat and then out into the blacks of B1 and C1 (see my diagram of the old setup below). Then I connected A2 directly to the whites of B2 and C2. This DOES work—the thermostat did power on but the heaters were turning on and off every 3 seconds. I have since learned that CASA DOES NOT support fan-forced heaters :(

For anyone interested, I did find a smart line-voltage thermostat that does support fan-forced heater: https://getmysa.com/.

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My old thermostat provides electricity to two wall heaters with fans (I believe the heat and fans always run at the same time). I'd like to replace the thermostat with the Wifi thermostat from Casa, which only has two wires, a line and load.

As you can see, the black and white wires coming into the old thermostat are both hot. Then they go out to two lines, B and C.

I don't understand what is going on after that. One wire coming out of the thermostat (D1) connects to the black wires of B and C and the other (D2) connects to the white wires of B and C.

How do I wire the new wifi thermostat?

Diagram of old thermostat wiring

Here is what the old thermostat looks like when I opened the back:

old mechanical thermostat

And here are some instructions from Casa, but I'm not sure they apply to my situation.

instructions from Casa Connect for the Caleo thermostat

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  • 1
    Have you looked at the "4 wire install" instructions?
    – ThreePhaseEel
    Nov 5, 2017 at 18:31
  • Yes, I looked at that. I thought about making A1 go into the new thermostat and then out into the blacks of B and C. Then I would connect A2 directly to the whites of B and C. But I'm still not sure.
    – David Scoville
    Nov 5, 2017 at 18:48
  • Ok I just tried what I commented above. Oddly the thermostat came on but the heaters kept turning on and off every 3 seconds.
    – David Scoville
    Nov 5, 2017 at 19:47
  • 1
    Curious...edit your question into that :) Hopefully someone can lick this mystery
    – ThreePhaseEel
    Nov 5, 2017 at 19:55
  • 1
    Post your update as an answer and I'll give you an upvote :)
    – ThreePhaseEel
    Nov 8, 2017 at 1:44

1 Answer 1

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1

I followed the instructions from Casa: I made A1 go into the new thermostat and then out into the blacks of B1 and C1. Then I connected A2 directly to the whites of B2 and C2. This DOES work—the thermostat did power on but the heaters were turning on and off every 3 seconds. I have since learned that CASA DOES NOT support fan-forced heaters :(

For anyone interested, I did find a smart line-voltage thermostat that does support fan-forced heater: https://getmysa.com/.

Improve this answer

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