Your thermostat is a very important part of your heating system and is extremely sensitive to the smallest change in reading the temperature. The thermostat control has very little moving parts than the rest of your heating system, but it can create problems to make your heater not run at all. If your cover to the thermostat was installed incorrectly or has been knocked by an object it can cause the heater from being able to start or even worse not work at all. If the thermostat was installed unlevel this can also cause the system not to operate correctly. The most common problem with thermostats is dirt. Dirt can change the calibration of your thermostat and not allow the heating system to work. For example if your thermostat was set for 69 degrees and your system is out of level or has dirt in it, the heating temperature is really running at 72 degrees.
By just having a 3 degree difference can increase your heating bill by as much as 8 percent. You should check your thermostat to make sure it is accurate every year prior to the beginning of the heating season. There are other problems that can create the thermostat not to work. These problems often are related to a bad switch on the base of the thermostat or a wire that has become loose or corroded. Check all your connections on the thermostat and clean any corrosion that may be visible on the wires.