Ive had about 4yrs faultless service from my two CM927 thermostats until the other day.
Initially it would send a continuous call for heat signal to the relay. It did this for a few days before I noticed at which point I removed and reinstalled the batteries and it seemed to work for another 24-48hrs normally.
Then the LCD went very faint/blank. Again I removed the batteries, tested for voltage supply from the batteries and reinstalled them. The screen returned to normal, but now the Room Temp is showing 39-42.5 degrees (!), all other functions and the screen contrast are working fine. I can not get it to show the correct room temp.
I have removed the batteries and replaced with a fresh set and the problem remains. I have reset the user program to factory settings but that hasn't solved anything.
Anyone know if there is a software reset routine for it? I cant find one in the literature. Im guessing 4yrs is out of warranty, but surely you'd expect it to reasonably work for longer than that
Ive emailed honeywell tech support - finger's crossed they have a fix or a replacement for me.