Curious, do you have fresh batteries in it? (If it takes batteries)

 

Hi...this unit doesn't have batteries.

 

I have the same model thermostat. Many reports of screen going blank, especially once the warranty is up. Replacements are very pricey and must be installed by a Lennox licensed Pro for warranty. Humidity sensor goes out of whack too. Never connected mine to WiFi. My suspicion is with it's Internet security. Is yours connected to WiFi? Does it come back to life if removed from the mount and re-inserted? If so, try turning off the Wifi and see if it runs again. If not, it's time to ditch these proprietary gizmos and go with DIY models like Honeywell RTH series or Sensi Touch 2 (by Emerson). Honeywell and Emerson are two of the original sensors & controls people.

You will need extra wires (the 10F81 runs on four wires). Unused extra wires may already be in the wall. If not, it may still be worth running the needed extra wire or two so you can take back control of your comfort If you decide to go that route, your system installation manual will have details on how to connect to a non-communicating thermostat. You can ask questions here as well.

 

I have the same model thermostat. Many reports of screen going blank, especially once the warranty is up. Replacements are very pricey and must be installed by a Lennox licensed Pro for warranty. Humidity sensor goes out of whack too. Never connected mine to WiFi. My suspicion is with it's Internet security. Is yours connected to WiFi? Does it come back to life if removed from the mount and re-inserted? If so, try turning off the Wifi and see if it runs again. If not, it's time to ditch these proprietary gizmos and go with DIY models like Honeywell RTH series or Sensi Touch 2 (by Emerson). Honeywell and Emerson are two of the original sensors & controls people.

You will need extra wires (the 10F81 runs on four wires). Unused extra wires may already be in the wall. If not, it may still be worth running the needed extra wire or two so you can take back control of your comfort If you decide to go that route, your system installation manual will have details on how to connect to a non-communicating thermostat. You can ask questions here as well.

That may not be possible.
The Lennox 10F81 is a communicating thermostat.....those Honeywell or Sense Touch are not.
It's a proprietary system. The upper end of the Lennox equipment won't work on anything but those stats.
I found out myself last winter.

 

Thanks! Mine IS connected to wi-fi, so I can control it from the app thank Goodness! I've tried removing it from the mount and replacing it multiple times with no luck. I'm fairly handy but not sure I'd be comfortable running extra wires but I'll look into it

 

If you have a Harmony 3 Zoning panel and modulating furnace there may be features that you need a Lennox thermostat for that a generic brand may not work with or you lose.

You will not get the error code info on a non Lennox thermostat. You can get them from the furnace but it is tricky to decipher the flash codes and reading them off the thermostat is a lot easier plus recalling them.

Flipping the DIP switches and reconfiguring the circuit board is not a easy DIY job and can be overwhelming for some people. Just sayin. It is not easy peasy plug and play.

 

The S40 is a direct replacement........it's about $1000.
I just had to replace my model 10F81 last winter.......
Sorry for the bad news.
rndiy explained it perfectly....
Which furnace / heat pump do you have?