Your home has a comfort system of some type (central air conditioner, furnace, heat pump, or boiler for example). What they have in common is that they all require controls to measure and regulate temperature and, in some cases, humidity. Because controls can go awry--and because they are relatively easy to check and fix--let's take a look at comfort controls as a component.

How Does It Work?

The main comfort controller is a thermostat, which is basically a switch that turns a furnace or central air conditioner on or off at a preset temperature. Comfort controls may also include a humidistat, which is a device that senses changes in the moisture of your home.

A thermostat controls the temperature by sensing a temperature change at its location and turning the furnace on or off to maintain the preset temperature. Your comfort system's thermostat may be either mechanical or electronic. An automatic thermostat can be set to lower or raise the temperature in the home during preset times by using microprocessors and thermistor sensors.

A humidistat can change the humidity in your home by controlling a humidifier or dehumidifier in your comfort system.

What Can Go Wrong?

Thermostats usually work without problem for many years, but they eventually may become inaccurate or fail. You can clean, adjust, and replace a mechanical thermostat. An electronic thermostat, beyond replacing the backup battery, will require either replacement of the entire unit or repair by a professional technician.

If a mechanical thermostat is acting up, consider replacing it with a programmable digital thermostat. They've become inexpensive and can help you save energy costs because of their efficiency.

The location of your thermostat can greatly affect the efficiency of the comfort system. Make sure your home's thermostat is not placed in direct sunlight, in a draft, or near an exterior door or window. If it is, you can move it, or, if it is located within a wall, you can pack insulation behind it.