Old System C-wire question (all help appreciated)

Hi there Wyze fam, apologies if this is in the wrong area, but I’m new to the community so thanks for your patience. I received the thermostat and thought with the C-adapter I’d be ok, but I’m a bit confused as to how the 5 wires end up on only 4 available terminals. This is my setup on an old gas heat system (photo attached). I think the adapter’s wires are long enough so as long as I pull them apart that shouldn’t be an issue, but can someone guide me as to where that 5th wire goes with only 4 available. Thank you all so much. I’m really loving the aesthetics and hope to get this baby fired up soon.

looks like the transformer on the left is for the thermostat. have you traced those 2 wires? You need to to find where the wires from the thermostat are connected. Post a pic of your current tstat wiring & also the wiring of the other end.

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Here’s the old faceplate with cover removed. The only wires I find in the basement are the ones in my original post photo. Thank you Ken.

this is outside my scope, gonna have to tag @speadie

Tape the red wire off on both ends. Take the Black wire off the Clock transformer and put it on the same terminal that the Green wire is connected to ( C ).
Then, on the wyze, connect the Black wire to C, the White wire to Rc, and the Green wire to W1.
Tell the wyze app that you have those wires (Rc, C, W1)
If, as soon as you connect the wyze, your boiler starts up or a fuse blows, then you need to switch the green and white wires on the wyze- I can’t tell from the picture which side has the boiler control on it, because the wiring is behind the fuse panel in the center.

If your old thermostat is in good condition, you might be able to sell it on ebay. Those old clock thermostats are something of a collectors item.


What are you like an expert or something!? Haha thanks so much man! Does this help clarify? The left side is scribbled thermostat and the right is clock. Trying not to blow a fuse if possible or worse . Ya think to proceed as previous message? I’m moms caregiver so I probably am in over my head with these pandemic projects. Much obliged.

In order for me to know which was which, you’d have to loosen the screws and remove that entire panel and take a picture of the wiring inside. but you have an extra fuse from the clock, which you could use if a fuse blows ( but it really shouldn’t)
And obviously, if you’re going to remove the side panel, make sure the power is off first.

As an alternative, is this the side of the boiler? do you see a relay anywhere inside? There are 2 armored cables going into that enclosure, where do they go? (one should be 110v, one should either be the switch or the thermostat wires)

I removed the face plate where the fuses are and that’s what it looks like on the inside if that at all helps. I feel like I’m in Diehard and any wrong move will blow everything up. Man I thought this would be easy. If you think your original wiring instructions hold true I’ll give it a go otherwise may look for a pro. Again, can’t say it enough. Thank you so much.

The wires go off to the right and I’m assuming go up behind the clock transformer in the smaller armored cable… Where does that cable go?

I’m 90% certain that the wiring I laid out for you will work. As I said, if it doesn’t, just swap the wire locations.

As an alternative, you could leave all the wires where they are on the furnace and just connect the black and red wires at the thermostat to Rc and C and the greenish blue and white wires to Rh and W1.
This will power the wyze from the clock transformer and switch the boiler on and off without having to find out which wire the boiler relay is actually attached to.
In order to do this, tell the wyze app that you have Rc, C, Rh, and W1 wires.

The clock hasn’t worked for a while so maybe that fuse is dead? Which of the two methods would you go with as a better bet? I think I may go with the option not touching the control panel. All this time I thought I’d need the C wire adapter. Fingers crossed, give it a go later today. Thank you.

So I went with your second recommendation not touching the control panel. The thermostat lit up with Wyze logo and I was able to setup through app after I skipped this warning - see photo. As of now, it just constantly shuts off when I try to ignite heat and scroll wheel on thermostat itself doesn’t show any menus? I got so excited when the logo turned on but now looks like a dud. Any more ideas? I’m gonna venmo you if we figure this out. Thanks again.

And just for giggles and process of elimination, I tried the first setup and that works! no error message from app etc. when I go to test I hear the pilot try to turn on but it’s faint and not enough to get it going. So the app and the thermostat are sending the signal but seems like the boiler now doesn’t have enough juice. Is it the spark plug? I’m sorry to be such a pain in the ass, but I think it’s almost solved!

Hmm. When you hooked it up with the clock transformer, did you tell the wyze app that you had Rc, C, Rh, and W1?

When you switched the wires, did you tell it you had Rc, C, and W1?
You will need to reset the thermostat and re-add it and tell it what wires you have each time you change something.

I did indeed, I followed your instructions very carefully. I had to turn the gas switch to off in basement bc it just kept trying to turn on with no luck. While it was on that meant the Wyze thermostat just keeps shutting off and on so didn’t even give me the time to reset to retry. Any idea why i would hear the pilot sorta tun on, but just not have enough ummmpphhh to get it going, like a little sound but not the full blast. Guess I’m SOL.

The transformer might not have enough power to run both the gas valve and the wyze.
You could buy a separate 24VAC “C wire” transformer and connect its leads to Rc and C if there is an outlet nearby. The clock transformer apparently only has 3VA, which is why it wasn’t powerful enough to run the wyze. It looks like the thermostat transformer is 25VA, which should be enough, but maybe the gas valve is old and draws more current than I’m expecting it to.

If I get that transformer, that goes in on thermostat end or panel end? Also, the C-wire adapter that comes with it won’t help huh? Thanks for your patience.

The C wire adapter that comes with it just gives you another wire if you don’t have enough in your run. Your issue is that your transformer isn’t powerful enough, so it wont be able to help with that. Because you have 2 unused wires in your run from the old clock circuit, you could connect a C- wire transformer to them and not have to deal with trying to run the wire directly to the thermostat.