One thermostat works, the other doesn't
 

Hi,

I recently moved into a new apartment. I have one thermostat on the first floor and one thermostat on the second floor. At first, both thermostats worked, but now only the second floor thermostat works. I purchased a new thermostat and installed it on the first floor, but no luck. To make sure I purchased I working thermostat, I installed it on the second floor and it works. I don't know what it could be. Any suggestions??? And how much might this cost to get fixed??? Thanks!!!

Hi Churley:
Thermostats work on a 24v system. You may have a burned out transformer or your heater may have a burned out contactor. Has the contactor been making a buzzing noise while the unit runs lately? That would be a good indicator of a burn out.
If these two attempts fail, you will need to trace the entire 24v system to find the trouble; could be a wire broken or an in-line fuse blown, etc.
Let us know how it turns out.
Glenn