C wire adapter

So where does this adapter go in a “normal” installation? am I supposed to just cut a large hole and let it hang in the wall void covered by the Wyze face-plate? should we put in an old-work back-box?

Are there any recommendations? I don’t want it visible to the room its mounted in.

I was really surprised that it doesn’t somehow attach to the backside of the face-plate

Welcome @GMan650!
The adapter connects to your furnace control board. What wires do you have at your thermostat and what terminals do you have at your control board?
Try the thermostat setup in the app (until the “find thermostat” part) even if you don’t have one so you’ll know what to expect.

one cable with 4 conductors at the thermostat. I have an Arzel PAN-HPP2 control board where zone 1 has 11 connectors but only 4 with these wires connected. the C is not in use. So it seems like I was wrong in thinking this needed to be installed at the thermostat. Your saying the adapter goes at the panel… uses the 5 designated connectors (which includes the C terminal)… then i use the existing 4-conductor cable up to the thermostat and connect with only the 4 wires at the Wyze thermostat (R, W1, Y, & G)

Yeah, I tried that and my furnace kept cycling on and off. Now I wired it with a new 5-wire right to the furnace and it is working.

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Correct!
The adapter sends the power down the G wire to the thermostat. You would wire the G to the C terminal and follow the setup instructions in the app.

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Thanks for all the helpful answers everyone. I have a use case that I do not yet see clearly answered in this thread - a gas fireplace with a simple relay that controls it (off when wires are not touched, on when touched). I know I need to use a 24v adapter to power the wyze thermostat. And I am fairly sure if I wire it right, this should work for a heat only application. Can anyone give me extremely clear instructions- or ideally a diagram - on how to connect this up? I am sure this would be helpful to future Wyzers! Thanks so much.

Correct, 24VAC adapter leads go to Rc and C. Load to be switched goes to Rh and W1, You lose the ability to cool if you are going this way with the wyze.


When you are setting up the wyze, make sure to tell it that you have those 4 wires in your existing thermostat. (Rc,C,Rh, W1) Polarity is unimportant.

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Awesome! So for simple heat relay use-get power from 24c adapter, and have relay on Rh + W1. Works great!! Thank you. Hope this helps someone else. For me, I got my gas fireplace working with the thermostat. Yay.

Thank you so much! The instructions MUST be corrected- they do not say to switch the G to the C!!!

On my furnace I see the wires: R, C, Y, G, W
My existing thermostat (nest) was connected to: Rh, O/B, Y1, G, Rh.
The Wyze app tells me I need the C-wire adapter. However, I have a C coming off of the furnace as you can see in the photo.
When I connect the C wire (blue) from the furnace to the C on the Wyze Thermostat, it gets power.
If I tell the app the wires as indicated from the furnace, it says I do not need the adapter.
It powers the furnace but it does blow hot air.

What is the correct wire configuration?
Why is it telling me I need C adapter?
Why does it change from Rh to Rc?

Here’s the wires coming off the furnace

Need a wider view of the furnace wires showing which bundles they go into.

Thanks Speadie. The issue was not the thermostat. It was wired correctly. The issue was the control module next to the wires on the furnace. I had disconnected it but not fully reconnected it. I plugged it back in and hear the click into place. Now when I turn on the heat, it fires up right away and blows the hot air after a minute or two like it did with the nest. User error!

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Do you have a heat pump?
Because the only reason you would have a wire in O/B would be if you have a heat pump. Your heat might be coming from your backup source completely, or your A/C might not work if you put a heat pump’s O/B wire in series with your thermostat’s C connection.

Not all wires that go from your furnace board go back to your thermostat, so I wanted to verify that that blue C wire actually goes to the same wire bundle that your thermostat wires go to, and that it isn’t just going to your outdoor unit.

I have the se issue as beaumac. It tells me I need the adapter bit when I looked at the furnace there is a c wire so now I have no clue what to do.

Any help would be appropriate.

Furnace wires.

C is feeding your outdoor unit,
I see a blue wire here, where does it go?
image
Also, is there a blue wire in the wall behind your current thermostat?

It’s too late for me to check where that blue wire goes right now so I’ll check tomorrow when I get done with work. We don’t have AC so I don’t think the c wire is going to an outside unit. There is a blue wire behind the thermostat bit not sure what it’s connected to if anything.


Amy thoughts?

If the blue wire in the furnace doesn’t go anywhere and the blue wire behind the thermostat doesn’t go anywhere, then connect it to C on both ends. This means your furnace will have 3 wires on C, that’s just fine.