Trying to get rid of Lenox thermostats

Hello all! New user here. I have a Lennox system with 2 SLP98UH070XV36B-07 Furnaces and 2 XC25-024-230-02 AC Units. The two zones in the house are wired to iComfort WI-Fi touchscreen thermostats. One of the thermostats broke and it is not covered under warranty. When I tried to replace it I found out that this discontinued thermostat is over $700 and the new model over $1,000. That killed Lennox for me but, since the heaters and ac units are still chugging along, I want to replace the thermostats with Nest or Ecobee. When I called Lennox to ask if I can do this, the guy told me they will not work and I have to re-wire many things.

Now, I don’t trust these people, and I understand that there is a way that I can do this “re-wiring” because it is not too complicated. A friend sent me here to ask, so hopefully, someone can give me a hand.

I found this topic Lennox furnace with ecobee3 (or nest) - Devices & Integrations - SmartThings Community, but it is from 2018, so not sure if it still applies.


The first issue is the basic hardware compatibility, so I would contact ecobee and ask them.

As I understand it, the primary issue you’re going to have is that you have a variable speed furnace and ecobee will only be able to let you do on/off, not switch between speeds. But they will know for sure.

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The Lennox folks won’t help you. I tried many times. Getting an Ecobee or any other normal thermostat to work with Lennox in Heat mode is easy. You’ll have to do some rewiring and yes the old post from 2018 is still valid. To get it working in AC mode is harder and I haven’t done it. I understand it can be done but you have to rewire things on the AC unit outside as well as the furnace inside. For the heater mode you only have to tweak the inside wiring as shown on the 2018 post so it is easier. I’ll never buy a Lennox heater again because of their attitude about using their own crappy thermostats that don’t work with ST or Hubitat. They do work with HomeKit and Alexa so I have as others have done hacked up workarounds like having our speakers tell Alexa to change the thermostat or making routines in Homekit to mimic what ST is better at doing. Anyway, good luck.

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Thank you kewashi. Not only their attitude but their price gouging practices. I can’t believe that a top-of-the-line Ecobee is around $250 and an outdated piece of crap Lennox thermostat retails for over $700. When I contacted their CS, their response was that they have no control over the retailers’ price. Umm…yes you do! If you give them thermostats at a high price and they mark it up, then the retail price is exorbitant!

This post shows how to do heat and AC. Again I haven’t tried it.

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Will see if this works. Thank you!