Wyze Thermostat - Wiring Question

My old thermostat only has 4 wires (No C). I completed the install using the C-wire adapter. The Wyze thermostat does not come on. The wiring at the HVAC control board seems ‘standard’. The wiring at the thermostat also seems standard. The one catch is that my furnace has a sump pump with a float switch. The switch appears to be in series with the R wire. At a loss on what to do next other than taking the float switch out of the loop (not a good long term solution) or bypassing it to see if that is the problem. I could use some suggestions. I have added photos of both ends and of my initial attempt.

Welcome to the Wyze community @Vpel!
Did you wire the pump into the thermostat adapter? Try leaving it in the original terminal with the adapter wire.
Could you also upload some pictures of the control board and your old thermostat wiring?

Thanks for the quick response. I edited the original post and added 3 photos. Terminals at the thermostat and at the controller. Wiring diagram representing what is currently in place. My first failed attempt. Additional details. Replacing Honeywell Chronotherm III. Heating (propane) and cooling (AC unit). Thanks for your help.

Looking at your wires, it looks like there’s a yellow wire wrapped around the whites for the thermostat that isn’t being used. Could you see f this wire is at the thermostat too? If it is, wire everything back how it was before and wire the yellow wire to the C terminal on the control board. Then select the C terminal during setup. You can then wire the thermostat with a C wire ass if you had one before.

I like how you think. Unfortunately that 5-conductor cable gets spliced to a four conductor cable right outside the furnace. Then the 4-conductor cable is routed through the house to the thermostat location. Looks like when this furnace was installed (about 12 years ago) the installer reused the pre-existing cable. Anything else you think I could try or am I out of options? Thanks.

Would you happen to have a photo of the Wyze backplate when you wired it?

Excellent suggestion @Brlepage

I did not think to take a photo of the backplate. What I recall is R to Rc, G to G, W to W1 and Y to Y1. The first letter is the signal name out of furnace controller. Second is position I wired it to at Wyze backplate. Thanks.

Using the C-Wire Adapter, G needs to move to C on the Wyze backplate. The G wire becomes C. Give that a try.

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You can test the float switch with a multimeter to see if there’s continuity (turn off your furnace so the circuit isn’t energized) or voltage across the switch during normal operation (should be a Normally Closed switch). Likely hasn’t failed in the course of time that it took to change the thermostat, but you never know til it’s ruled out

Yeah, what he said. :slight_smile:

My wiring is the exact same set up. Mine runs the condensing unit and heat at the same time.

So you got it to work without changing how the condensate pump is wired in?

Yes the pump is wired to from R on the c connector trough the pump switch and back to the stat wire .

What do you do if your furnace doesn’t have a C label for the circuit board? I have G,O,B, W1,W2,W3, R,BK, T,Y,YLO. I don’t know where to connect the c wire to

Will it work with my thermostat? It Honeywell TH9421C1004
There is no letters, just numbers 1, 2, 3

Welcome to the community @dimashah!
Could you take a picture of your control board?

Thank you so much it worked!! You are guys are such a life saver!!

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Here you go

Hi, Let me know if this is the right thing. Thanks

Yes it worked. Thank you so much for helping me through this!