Experts recommend that you adjust your heater thermostat at least once a year. Dust and time can cause the sensitive sensors in a thermostat to get out of balance, and could result in erratic heater operation. Adjusting them is an easy process, and requires only a small flathead screwdriver.
Setting the Room Temperature
Pull the face off the thermostat. You should see what looks like a coiled of metal with a small screw set in its center. This is used to synchronize the room temperature with the temperature measured by the sensors. Using a digital thermometer, make small adjustments until the thermometer matches the reading given by the thermostat.
Adjusting Heater Operation
There is a second adjustment which affects the way the heater runs, and how often it turns on. This will either be a sliding adjustment, or another small screw, usually with a gradients marked around it's edge. Reducing this setting will cause the heater to run less often, and increasing it will cause the heater to run for longer periods when it is operating. In some cases, this setting is actually two different controls, so look at the markings inside you thermostat to make sure you are adjusting the correct one.