Replacing Ecobee Stat 02 with Amazon Thermostat. Taco Relay with Gas Fireplace.

mognog

Hello, I just moved into a home that had a Berkshire Lopi gas stove/fireplace connected to an old Ecobee Stat 02 thermostat via a Taco relay. The Ecobee servers connectivity ended which basically removed any wifi ability of the thermostat. I replaced it with an Amazon smart thermostat. Bummer when companies stop supporting devices but this was released in 2008, I'm actually impressed with the 16 year life. I have no confidence in Google hardware support which is why I chose Amazon over Nest. I actually worked on Google hardware for several years :)

I researched here quite a bit and also on Ecobees support page and got everything up and running in the first try but I'd still love to run it by the experts here to make sure this set up is correct and safe as the home is in the mountains and I rely on keeping it above 45-50F to keep the plumbing safe.

This is the original set up. Left module = Taco Relay. Right module = Ecobee EIM.

In the original set up, R and W was wired from the fireplace (R = TH) (W = THTP) to the Taco Relay. 120v power to the Taco Relay. Then the Taco relay to the Ecobee EIM. From the EIM to the Thermostat. The brown wire on the bottom right goes to the proprietary Ecobee connector (D+, D-, 12V, GND).

https://support.ecobee.com/s/articles/My-communicating-thermostat-has-non-standard-proprietary-connectors-can-I-install-an-ecobee-thermostat

Ecobee's instructions were to basically bypass the EIM directly to the thermostat. So I took the R, W and C (greenish wire) from the Taco relay and wired those to the R, W and C on the new Amazon Smart Thermostat. There was a blue wire connected to R on the Taco Relay to the EIM that I was unsure of. I disconnected this and ran the other wires as noted above.

So my wiring looks something like this. Also shown above in the photo.

Taco SR 501-4 Wiring Below

Everything seemed to function fine. Fireplace turned on when called for heat from the Thermostat. Fireplace turned off when temperature reached at Thermostat or if powered off by Thermostat.

Could anyone, maybe the famous EdTheHeaterMan :) check if the wiring is ok and safe? Also was removing the blue wire connected to the R the right move? Or should that have stayed and if so, where would I connect it on the Thermostat?

Bonus question, I'm not sure how long that Taco relay has been there but it's at least 8 years old. How reliable are these? Do I need to replace it?

EdTheHeaterMan

That wiring looks perfect.

Taco Relay shoold last another 20 years or so. Unless the relay is short cycled about 20 times an hour, 24/7/365 (with a vacation day every Feb 29) then it may only last 10 years.

mognog

Thanks @EdTheHeaterMan! I read several of your posts to figure out what to do here, you taught me well or I just got lucky. I'm a mechanical engineer so this is all greek to me.

Do you know what the blue wire on the original set up was for? My first thought was to leave it and maybe run it to Ground on the new thermostat, but I couldn't figure out the reason it was there and I am all for simplification so I removed it. Everything worked so I kept it that way for now.

Thanks again! I'll sleep better at night knowing you approve of the wiring 🙂

EdTheHeaterMan

i usually use Blue for C or COM on 24 VAC systems. It is just easy for me to do diagrams. That way when I explain to other mechanics how to wire stuff it is easier. Green is commonly used as the FAN relay, so I would have left that one unused. But I have found that Electricity is colorblind and can not follow direction arrows on the diagram. So, I don't use arrows to tell the electricity which way I want it to go. I just let it follow the path of least resistance. It can be shocking when you get it wrong. As a matter of fact, I had to fire an electrician from my crew because I caught him blowing fuses on company time. " Keep your personal life for after hours" I said!

mognog

Yep, I noticed Blue was typically used for C. Blue originally here was connected from the R on the Taco relay to the Ecobee EIM. Green was already connected to COM on the Taco Relay so I kept the green and ran it to C on the Thermostat.

I just didn't know why the Blue was wired from R on the Relay to the EIM in the first place.

EdTheHeaterMan

Blue may have been used to connect the R terminal from something to power the EIM. The EIM does not look like it has its own 24 VAC power source. Looks like your EMI needed 2 places for a 24 VAC source.