Using a thermostat to control central heating can save you energy and money

According to the Energy Savings Trust (EST) turning your room thermostat down and reducing your room temperature by just 1°C could cut your heating bills by up to 10% which typically saves around £55 per year.

Stable temperatures save energy

Many thermostats have a 'switching differential' of about 1.5°C. This means they switch the heating on until the room reaches the target temperature, then switch them off until the room has cooled to target temperature minus 1.5°C.

As a result the room temperature cycles up and down by at least 1.5°, probably more because it takes time for heat to get from the heater (radiator) to the thermostat.

Even a 1°C change in temperature can be noticeable. For instance, suppose you find that 20°C is comfortable, but you begin to feel cold at 19°C; due to the 'switching differential' you may have to set a basic thermostat to 22°C to feel conformable all the time. However, this is a waste of energy and money because for much of the time the room is hotter than it needs to be.

So, what does a room thermostat do?

Most common room thermostats are simply an On/Off control and this and this is the method of control used by most heating systems in the UK.

A standard thermostat simply allows the heating system to come on or off depending on the room temperature, a separate control (Programmer) is usually used in conjunction with the thermostat so the boiler is only on at certain times. Programmable thermostats combine both functions and switch the boiler on and off when programmed and depending on the room temperature.

When the controls switch on, the current opens the gas valve in the boiler, strikes a spark and allows the boiler to burn whilst there is a live supply to it. When the current is interrupted, the boiler ceases to fire.

Some thermostats are "intelligent" and predict the anticipated heating and cooling based on historical performance, this is usually called "Time Proportional Integral" control (TPI) and can offer significant energy savings.

What types of thermostats are available?