Thermostat and outside boiler

Ok I have a normal forced air furnace and the wyze works great for that. I only use this to heat for a couple weeks. I also have an outside wood boiler system that I use for main heat during the winter. The boiler system runs through a radiator in the furnace plenum. When I need heat I would need only the fan to kick on. Is there a way to accomplish this with the wyze?

This seems to be a pretty specialized situation. I suppose you could manually turn the fan on under Controls, just leaving it run whenever you engage the outside wood boiler system…

Put a switch inline with the thermostat wire, so that if the switch was flipped one way, it feeds the gas furnace, and when you flip it the other way, it feeds the other furnace fan.
You’d just need to manually flip the switch when you want the wyze to control the other device.
assuming the 2 furnaces have different transformers, you would need a 4PDT switch to switch all the wires at once (R, C, W, G)


using this switch

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I think think this might be down a good path …the following is a little better explanation.

The boiler system only circulates the hot water through a radiator in the forced air furnace plenum. When i need to call for heat I only need the fan to turn on as it already has hot water (180degree) water that will warm the air. The gas part does not need to turn on at all.

In the past I would jumper power and the fan to a rotary thermostat. The fan wire would be hooked to heat so when called for heat it would just turn on the fan. But with the wyze now I do not want another thermostat hanging on the wall, it just looks bad. And with smart ones you would think there could be a way to accomplish this.

Yes I could, but not going to do that every time I need to heat the house. I would be having to wake up all night long as the temps dip way into the negatives in the middle of winter…lol.

I do think I did explain what I want better down below in another reply. Please see that if you want to understand more.

In your case, you’d want the fan wire that goes to your blower fan (G) connected to the W terminal on the switch from the thermostat. You still need R and C, to power the wyze, and make sure that you’re feeding the right transformer’s voltage to the fan relay coil.

Can you use them as two separate stages of heat? W1 and W2? You probably have a switch on the furnace to turn it off when you don’t need it, and maybe the same on the radiator fan.

Very importantly, there are two separate power sources involved, and they will turn off. I’d power Wyze with its own transformer, and use separate relays for the furnace and radiator fan (look up a device called a RIBU1C for the relay. I see them all over eBay, $15.00 with free shipping. )


No this is one unit. A forced air furnace that just uses the fan to blow air across a radiator in the plenum. The air gets heated and heats the house.

As mentioned above in a reply I use the forced air with LP only for the first month about. Until the temps outside start staying colder during the day. I then fire up the outside boiler which just circulates warm water through the radiator in the plenum. The goal is to have the forced air furnace still do the heating by turning on its fan only and not igniting the burners.

This is what I used to do before Wyze

This is what I want to get to. Click Here It would be great if the Wyze operated as a multistage thermostat

So maybe, have the LP as the second stage. It will operate as needed if for some reason you don’t want to get up to feed the boiler some night. For the first stage, use an aquastat to tell you when you have sufficient heat in the water. Wire that is series with a relay fired off of the first stage of heat. Put that series combination in parallel with the fan contacts. That would make it fully automatic. You should not have to intervene with a switch.

The sequence of operation would be something like this.
On the first call for heat, when the water from the wood boiler is warm enough to heat, the fan will run, blowing air across the hot water coil.
The second call for heat will happen when the first stage cannot keep up, or is not operational. The second stage will operate the LP burner, and the fan will operate via the bonnet stat in the unit.

Does this make sense?

In this case, I’d still use a switch, but all it needs to do is convert the W1 signal from the thermostat to G on the furnace, so it can be a SPDT switch.
When you wanted to switch the furnace to wood heat (fan only), you would just flip the switch.


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If the wyze could have it’s second stage setup to do that, it would be nice, but it will likely think that it’s taking too long with the wood boiler and kick on the gas heat randomly throughout the winter.

Speadie, I would agree if the thermostat was starting the boiler.

My understanding is that the Wyze thermostat would not be energizing the boiler, so there should be no delay. There would be hot water available without delay when he is manually firing the boiler. The thermostat would be simply energizing the fan, with already available hot water. This should be even faster to get heat than going through the induced draft fan / heat proof / bonnet stat / fan sequence of the LP furnace. The only thing I would like to have available when using LP for backup heat when he doesn’t feel like firing the boiler off is an adjustable interstage differential setting.

I would want the second stage (backup LP heat) available automatically, in case of illness, unexpected travel, or some other reason that the wood boiler is not firing.