Hello. I have an older Williams furnace in my new place. Can I use my Wyze thermostat with it? The model # is 465FX-R NAT.
Thanks in advance.
What does the wiring look like at the thermostat location?
Bat signal for resident pro: @speadie
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Yes, however as this is a millivolt furnace, you will need a C transformer and an Normally open isolation relay.
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I’ll have to pull the cover off and have a look. Can I post photos here?
Oh my…This might be above my head.
it’s not too difficult. I’ve linked the items you would need. For the isolation transformer, pin 1 would need to be connected to W1 on the wyze and pin 3 to C on the wyze. Pin 4 would be connected to W1 on the furnace and pin 2 would be connected to C on the furnace. The wires from the C transformer would be connected to Rc and C on the thermostat, no need to worry about which ones go where.
Isolation transformer might not be necessary, but some people have reported erratic behavior on milivolt systems without one.
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Circling back to this. Without the isolation transformer, what would the wiring look like? What does the C transformer do?
Also, on the wiring from the furnace to the thermostat, how do I know which wire is which? Sorry for all the questions.
C transformer is needed because your furnace doesn’t have a 24v power supply, and the wyze thermostat needs that to operate.
Without the isolation relay, you have the C transformer connected to Rc and C, and the 2 wires from the furnace connected to Rh and W1
Polarity shouldn’t matter.
During setup, tell the wyze that your old thermostat has the following wires: Rc, C, Rh, W1.
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You’re awesome, sir. Thank you so much. I’m buying the transformer and installing this weekend. Appreciate you.
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