There are two main types of home thermostats: electromechanical and electronic. Deciding which one you want to control your home's air conditioning system is an important decision. In order to make an informed choice, you should understand how these two types of thermostats work, as well as their similarities and differences. The following will explain them to you.
These days, electromechanical thermostats are considered a bit old-fashioned, in part because they operate on a simple mechanical principle. Inside the thermostat, there are two pieces of metal joined together (known as a bimetallic strip). As the temperature inside the room changes, this coil of metal will contract or expand to make contact and activate the thermostat. It's somewhat similar to the way a light switch works. When flipped up, a switch allows current to flow to the light (or in the case of the thermostat, to your heating and cooling system).
In some models, this bimetallic strip is combined with a mercury switch. A mercury switch is a small plastic tube full of mercury that is designed to tilt as the bimetallic strip contracts or expands. The mercury in the tube acts as a liquid conductor, opening or closing the electrical contact. If your thermostat controls both the heating and cooling in your home, both ends of the mercury switch will have contacts. One side will control heating and one will control cooling, with control switching back and forth between them with the tilting of the bimetallic switch.
Rather than using bimetallic strips and mercury-filled tubes, electronic thermostats monitor the temperature in a room using heat sensing receptors. These thermostats have electronic circuitry designed to collect and respond to digital information, turning heating and cooling equipment off or on in response to the data it gets from the outside environment. Essentially a small computer, electronic thermostats can be programmed ahead of time with specific settings. That way, the house can be warm when you wake up, cool while you are sleeping and set to other specific temperature schedules while you are at work or away on weekends.
Thanks to their electronic circuitry and digital sensors, electronic thermostats are much more accurate than electromechanical thermostats. A condition known as "dead band" can occur with bimetallic strips and mercury switches in which the thermostat fails to activate the heating and cooling system even if the temperature falls well below or above your setting. In addition, electronic thermostats last much longer because they lack the many complex moving parts that mechanical thermostats have.
For more information about your thermostat options, contact a company like A/C Repairs, Inc.