How to hook up a wifi thermostat to a millivolt pellet stove

[Skier76]

Disclaimer: I'm not an electrician or a stove tech; just a hobbyist. Here's what worked for me on my stove, it was a very simple process.

I opted to use a CT-50 Wifi Thermostat from Radiothermostat.com. They had a Black Friday deal for $75. I have this exact same t-stat running my oil boiler and central air system. I've had that setup for about 4-5 years. It's essentially the same unit, but branded as a 3M-50 and was sold at Home Depot for a few years at $99.

In addition to the thermostat, I purchased a 24V AC transformer from Radiothermostat.com to power the unit. Stoves don't have a C (Common), so this will power the wifi radio.

http://store.radiothermostat.com/24VAC-Transformer-CT-Transformer.htm

The wiring for this turned out to be very very simple. You're essentially hooking up 4 wires: Two from the stove, two from the transformer.

Here's some info I found here regarding the terminals to use for the stove:
"likely it is two wire as that is all that is needed, the RH (red) and white (W) no matter which is which.. " https://www.hearth.com/talk/bookmarks/1203/view-item (See attached pic below for a picture straight from the installation manual)

For the power wires, this is directly from radiothermostat.com:
"24VAC power adapter provides power to the thermostat from any standard 110VAC electrical outlet. Intended for use with HVAC systems that do not have a “C” or “Common” wire. Attach to the "Rh" terminal and the "C" terminal. Either wire can connect to either terminal."

The attached pic below shows the wiring:
The transformer wires go to the C and RH terminal; either wire can go to either terminal.
The stove wires go to W and RH (you'll have two wires in RH) either wire to either terminal
If you look closely at the pic, you can see the jumper is still in place.

That's it for wiring. Once it's all hooked up, plug in the transformer and the t-stat will turn on.

 

[Skier76]

Now that it's up and running, you'll need to connect it to your network. You can do this on a windows machine with wireless. This is a slightly more complex method. I opted to use an iPad which was very very simple. You basically connect directly to the thermostat, enter your wifi username and password and connect it to your network. From there, you can link it to an existing radiothermostat account. Since I have two thermostats, I can see both in the app.

The app received a neat update recently. You can now see run-time along with the room temperature. I've attached a pic of what it looks like below. The red bars are run-time per hour; the green is room temperature. Of course, you can adjust the temp remotely from your phone or tablet via the app.

I have this unit hooked up to a Regency GCI60, but this setup should be very similar to any millivolt stove that has a two wire t-stat hookup.

How's it work? In a word, "Outstanding"

In high/low mode; the stove will run at whatever heat level you have it set at until it reaches the setpoint. Once that happens, the stove will go to it's lowest setting until heat is called for again. It then ramps back up to the preset heat setting. I run high/low when we're at work for the day during the regular burning season.

Auto/Off Mode: I've geeked out a bit over this mode. In this mode, the stove runs at whatever setting you have it at, then drops to low if the t-stat stops calling for heat. If it doesn't call for heat for 30 minutes, the stove goes into shutdown mode. When heat is called for again, the stove fires up.

I've done a few experiments in this mode and it works perfectly. Before leaving the house (if we go away for the weekend), I fill the hopper with pellets. I then set the thermostat for "cool". This will eliminate it calling for heat at all. A few hours before we head home, I set it back to "heat". The stove will then light and run at the setting I left it at; usually 4 or 5. I have to say, it's pretty nice to come home to a house that's in the 70's after you've been away for a few days.

Any questions, just let me know. I'm really happy with this setup. I have a feeling over the next few years, a lot of this functionality will be built into new stoves. But for now, this is an easy work around.

 

[OK_Bill]

Great post!

I've been looking at this technology with the idea of controlling my Harman Accentra pellet stove *plus* two large HVAC units all through one WiFi system. For the pellet stove, I want to have the thermistor (heat sensor) mounted remotely on the opposite side of the room, which is where it will need to be for proper heat control in my home.

Question: Where is your CT-50 physically mounted?

 

[acammer]

Sounds like a slick setup. Someday I'll spring for a wifi stat, just can't beat that kinda convenience.

 

[hyfire]

Sounds like a slick setup. Someday I'll spring for a wifi stat, just can't beat that kinda convenience.

They are nice, but you also need a camera setup to make sure the stove is working and everything is OK... and a Wifi smoke detector.

 

[Skier76]

OK_Bill,
I have it mounted somewhat near the thermostat I have running the oil burner for that zone (downstairs level in a raised ranch). It's mounted at the same height as the other t-stat. I'll see if I can get a pic for you; it's a bit hard to explain where it is in relation to the stove. It's in the same room, but on a wall that's not in the direct path of the heat output of the stove. It's worked out well because it allows the room to heat up move evenly.

Part of what made this entire setup work is where my stove is mounted. I was able to run the t-stat wires from the stove, into the room the boiler is located in. From there, I used low voltage wire tacks to attached the wires to the studs. I did the same with the t-stat transformer. Luckily, I had an outlet already in the boiler room and the transformer came with plenty of wiring.

hyfire,
I've kicked around using an IP Camera. I have two Foscams at each house, so it would just be a matter of setting one up in the room and pointing it at the stove. However, the app gives you a pretty good idea of what's happening. If you look at the screen cap I attached, you can see when the stove shut down and the temp dropping. You can see the opposite when you turn it back on. But to your point, a camera would certainly give you a better idea of what's going on.