Go back to: See also: What is a thermostat?A thermostat is a device that allows you to control the temperature inside your home by controls the functions of a heating and/or cooling system. Today's electronic models are a vast departure from earlier mechanical styles. Microprocessors allow you to program your home temperatures to suit your lifestyle, so you can keep things comfortable while you're home and automatically set back your temperatures to save energy when you're away or sleeping.How do the thermostats work?A typical thermostat turns on the heating device whenever the temperature falls below a certain temperature and turns it off whenever the temperature rises above another temperature. Those two temperatures are slightly separated so that the heating device doesn't turn on and off too rapidly, and are usually set within a couple degrees from the desired temperature (also called a set point). If, for example, you set your thermostat to 68°F, it does not maintain the temperature precisely at 68°F. The temperature will fluctuate between approximately 67°F - when the thermostat turns your heating device on and 69°F - when it turns your heater off. More sophisticated models can also control cooling devices - like turning an air conditioner on to cool the room down faster and turning it off when the air reaches the desired temperature.What are the different kinds of thermostats?There are three main kinds of thermostats:Electromechanical thermostatsIn a typical electromechanical thermostat, a coil made of two different metal strips sandwiched together tips a small mercury-filled glass bottle. As the temperature changes, the two metals expand differently and the coil winds or unwinds. As it does, it tips the glass bottle and the mercury rolls from one end of the bottle to the other. When the mercury falls to one end, it allows an electric current to flow between two wires and the furnace turns on. When the mercury falls to the other end of the bottle, the current stops flowing and the furnace turns off. So the winding and unwinding of the coil controls the furnace and the home temperature tends to hover at the point where the bottle of mercury is almost perfectly level.These are the oldest kind of thermostats. Although newer digital models are quite popular these days, electromechanical thermostats are still widely spread because of their simplicity and cheap cost. Their main setback is that they are less accurate than digital ones and cannot support programming features. Digital manual thermostatsDigital thermostats work in much the same way as older electromechanical thermostats did, except that the metal coil is replaced with an electronic temperature sensor. The microprocessor inside compares it's readings to the desired temperature you select. Then, it gives start and stop commands to the heating or cooling system to bring the temperature to a level that makes you comfortable.While digital thermostats are more accurate than electromechanical ones, changes in their temperature settings still have to be done manually. Digital programmable thermostatsProgrammable thermostats basically work the same way as the digital manual ones, but they are far more convenient. Once you program the thermostat to customize the system's operation to fit your lifestyle and schedule, all you have to do is relax and let it do all the work. You simply program into its memory the temperatures you need, at what time of the day, to stay comfortable and save energy all season. You only need to program it once - until the season or your lifestyle changes.Depending on the model, a thermostat can be programmed in one of four ways:
What are the benefits of using a thermostat?
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