Heat won't turn off

[mrinella]

Hi,
Starting sometime yesterday, my thermostat will not turn off the heat. Its currently about 10 degrees warmer in the house than the max temp on the device is set to. I've tried many things, but the only way I can get the heat off is to shut off the breaker. Even when the thermostat says it is off, the heat is running. I've had it installed since July 2011 without any issues until now.

Thanks,

[blaine]

What kind of heat, what model thermostat?

If you have a wire on W (normal heat return wire) disconnect it from the thermostat, if the heat stays on, the HVAC has a problem.

With good batteries reset the thermostat and put it in the OFF mode; then when you disconnect the W wire, if the heat goes off, the problem is the thermostat.