You’re cold, so you turn the thermostat up. You get hot, and you turn it back down. Have you ever wondered exactly how thermostats and controls manage temperatures in your home or office? It’s one of those little conveniences that you might just take for granted. First of all, the thermostat is not just a glorified power button. Its main job is to maintain a constant temperature so that you don’t have to manually turn the heat or air conditioning on and off all day. In fact, the roots of the word thermostat basically mean temperature and same. Pretty simple, right? But how exactly does a thermostat work?


Although older types are mechanical contraptions that use mercury to trigger changes in heating and cooling equipment, most modern thermostats and controls manage temperatures by means of a digital interface. The digital thermostat uses a thermistor, or thermal resistor, to read the ambient temperature of the room that it’s in. It uses this temperature reading to trigger the heater or air conditioner to cycle on or off. Most digital thermostats are programmable.


If you have one of these digital thermostats, make it work most efficiently for you by programming it and then leaving it alone. For example, set the heater thermostat to warm up a bit an hour or two before you usually get up in the morning, then to keep the house cooler during the day if no one will be home. Set it to a cooler temperature again when you will be going to bed. A common misconception is that thermostats and controls manage temperatures on demand, so many people turn the thermostat way up whenever they get cold. This is counter-productive, since the thermostat’s only job is to shut the heat off when a certain temperature is reached, not to produce heat quickly. If you turn the thermostat too high, you will only waste energy when you overheat the house, and wasted energy means wasted money.