Thermostats ensure your home heating system stays at a desired temperature. Combining the Greek-derived components 'thermo' (heat) and 'stat' (stasis or static), the term roughly translated means 'keeping the temperature the same'.

Types of thermostats

Many homes feature a thermostat that controls the temperature of the entire property. That means if your thermostat is set to 19 degrees, all radiators will be turned on when the temperature falls below that level.

Thermostatic radiator valves (TRVs)

Thermostatic radiator valves are used on individual radiators, offering the power to control the temperature in particular rooms. This system might be useful if you have rooms that are especially cold, or especially warm.

Wireless digital thermostats

Offering even greater accuracy than mechanical thermostats, wireless digital thermostats are becoming increasingly common. An electronic sensor compares the actual temperature with the desired temperature by way of advanced control software. These systems are effective at ensuring energy efficiency.

Internet-linked smart thermostats

Smart thermostats learn how you manually control the temperature in your home at various times of the day, or how your usage differs between weekdays and weekends. It develops a heating schedule that fits with your household. The level of control offered by internet-linked smart thermostats also mean you are less likely to simply leave your heating on, thereby saving you money. You can also switch on your heating remotely with your smartphone - so your home is warm by the time you return.

Technologies used in thermostats

Thermostats are distinct from thermometers, which only measure heat. Thermostats control heat.

A variety of technologies are used in thermostats. These include:

Bi-metal strips

This system features two combined strips of metal, one iron, one brass. Iron expands more than copper, causing the strip to bend as the temperature increases. As the strip heats, it disconnects from a circuit, which cuts electricity flow, thereby turning off the heating. When the strip cools, it moves back into the previous position and the heating comes back on.

Gas bellows

This system works in a similar way to the bi-metal strip, but is more sensitive. It uses metal discs between which are gas-filled bellows. When the temperature rises, the gas in the bellows expands, pushing the discs apart and breaking the circuit - which turns off the heating.


These thermostats harness contained wax which expands as it heats, pushing out a rod that breaks a circuit. Wax is used in a variety of thermostatic systems - such as showers and car engines. It is also used in thermostatic radiator valves (TRVs) - see below.

Digital thermostats

Digital thermostats are increasingly common in modern heating systems and, as mentioned, offer greater accuracy than the mechanical systems listed above. always recommend seeking the services of a professional tradesperson If you're not entirely comfortable carrying out repairs or maintenance by yourself.