What Is the Thermostat?

The word "thermostat" is derived from two Greek ones: "thermo," which means heat, and "statos," which means standing or static. A thermostat is what "keeps the heat the same." When the temperature gets cold, the thermostat activates the heater. When the temperature reaches a set level, the thermostat shuts off the heater.

How Thermostats Work

A thermostat must be able to "read" the temperature of the living space and activate the heater when temperatures get low then shut off the heater when the temperature is "just right." There are a few mechanisms that can get the job done, but we will go over two of the more common types: those that use bimetallic strips and those that use gas-filled bellows.

Bimetallic Strip

A bimetallic strip is two different metals bolted together within the electrical wiring. This strip acts as a switch which turns the heater on and off. Here’s how.

You set the temperature at a desired level which activates the heater. As things heat up, so does the bimetallic strip. However, one of the metals in the strip expands more than the other, bending the whole strip very slightly – but enough to disrupt the electrical circuit and cut the electricity supply. This turns off the heater.

Once the temperature cools, so does the strip. As the strip, and the two metals, cool down, the strip bends back into its original shape and restarts the electrical flow. This turns the heater back on.

Gas-filled Bellows

Traditional thermostats use the bimetallic strip, but these can take a long time to heat up or cool down. An alternative design senses temperature changes more quickly.

This type of thermostat uses a pair of metal discs with a gas-filled bellows in between. The metal disks are corrugated, meaning they have ridges, which gives them a large surface area and makes them springy and flexible. When temperatures rise, the gas in the bellows expands and pushes the discs apart. The inner disk, in turn, pushes against a microswitch which turns the electrical circuit off. When temperatures drop, the discs move back toward each other and switch the electrical circuit back on.

Need a Technician’s Assistance?

As you can tell, the thermostat has very sensitive components. Damage or even dirt can disrupt the whole system. If your thermostat is not activating the heater, then call Rooter Hero to have a dedicated technician come by and inspect your unit. We are ready to arrange an emergency heating repair in Davis today.