Has anyone here installed a smart thermostat with a variable speed Trane AC Unit?

I’d like to say that we just had a new Trane installed, and that the challenge of finding a smart thermostat has been thwarted by the incompatibility with variable speed motors, but the fact is, it’s been 10 years since we had it installed. Time really can fly.

I tried to install a Nest thermostat years ago, and it failed because of the variable nature of the motor. Trane makes a thermostat with a ludicrous price that works with my unit, but since it’s been 10 years, I’m on the hunt for something that’s not so expensive and doesn’t require a cloud account to operate.

So, I’m reaching out to the community to see if there’s a reasonable alternative that works well with HA and works with the variable speed Trane system.

Any A/C experts out there?

I have an American Standard variable about that old. As far as I understand the only ones that support the Trane Variable Speed is the American Standard / Trane Acculink head units themselves because that’s where the logic is to drive the darn thing. If you put something like an ecobee or Nest you get operation but lose all the variable speed benefits… (I may very well be mis-stating that, or things could have changed in thermostat world but it was how it was described to me by a reputable Trane tech - not trying to sell me a thermo - a couple years ago…)

I’ve got an XL950 but it’s not supported anymore and it works fine - I’m probably moving mine to an XL1050 next year. The Nexia Integration drives these thermos for HA and while cloud, I do have full control of the thermo except when the network drops. (The 2.5Ghz wifi in these need some love… Make sure you have the latest firmware when its installed.)

The problem we had was that the Nest wouldn’t push the motor at it’s full speed, rather it’s slowest speed, so while it would work it would blow really slow…

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Yep that’s the net result - it only runs on the lowest speed. You have to use a Trane head unit. I asked my friend about a Nest or Ecobee and basically the word was you can but you won’t like it - describing exactly what you are experiencing.

So it looks like I’m stuck with the Trane…but that raises another question. How is it that the current thermostat has been working? Have we potentially been running our variable speed unit at full speed for 10 years without realizing it? The current thermostat is a basic programmable honeywell with the old LCD screen and simple M-F SS programming.

Unknown, likely. Whats definitely affected by non Trane here is the way they did variable speed on those model and the thermos (and had I known I would have bought a Lennox)

Thats said as hot as it’s been this year Mines 100% all the time anyway.

But what info know is everyone I’ve talked to when I’ve asked about an alternative thermo. I get ‘no, if you want it to work as designed go XL950/1050’

I considered buying a spare when I get the 1050, but I’m just going to replace the 950 before it fails and box it as the spare.