top of page

The optimum room thermostat

You don’t need to wait until your boiler is replaced - modern heating controls are compatible with all types of boilers, and until March 2027 a 0% rate of VAT applies to both the installation of heating controls and the cost of the controls when installed separately from a boiler replacement.

Modern room thermostats offer far more functionality and potential for energy savings than older versions. For the optimum performance you should aim for one that is a programmable room thermostat, with load or weather compensation, and smart functionality. Thermostat products can have one or all of these features, and each offer real benefits as described below.

Programmable room thermostats

These days around half of all room thermostats installed are ‘programmable room thermostats’, which combine both the timer and room thermostat in one package. As well as being more convenient, there is the additional benefit that you can set different room temperatures at different times, giving you more power to make energy savings.


Load compensation and weather compensation

These functions improve the running efficiency of your boiler. Much like the miles-per-gallon of a car, this means that you get more heat per kWh of energy you pay for.

Traditional room thermostats send a simple on/off signal to the boiler. They turn the boiler on when the temperature falls below the setpoint, and off again when it rises above setpoint. With load compensation the thermostat adjusts the output of the boiler in relation to the predicted heating needs. Weather compensation is similar but also includes outside temperature data in the calculation. Both result in closer control of temperature and more efficient boiler operation, so you get better comfort and lower fuel bills while simply using the heating system the same way you did before.

Control manufacturers must indicate a Temperature Control Class number on their packaging so this will help your installer identify a suitable device. Your current thermostat is likely to be a basic Class I, but if installed within the last two years may already be a higher class so do ask your installer to check.

Ideally you want a control that communicates directly with the boiler; either a Class V (load compensation) or Class VI (weather compensation) would be suitable. If your existing boiler cannot be set up to communicate with a control, or is just of an older type, then a Class IV control (on/off load compensation) can offer a similar benefit. Your installer can advise you on which of these is most suitable based on the make and age of your boiler.        

Research carried out at the University of Salford in 2020 demonstrated that the amount of gas used by a boiler for heating can be reduced by 12% by replacing a standard Class I room thermostat with a Class V or VI room thermostat. They also show that this saving would be 10% with a Class IV thermostat.

Smart functionality

Room Thermostats can also be ‘smart’, allowing you to adjust settings remotely (usually through an app on your mobile phone) so you can easily adjust your heating to suit your lifestyle. They may also sense whether you are in or out and adjust the heating settings automatically. The overall impact is to make sure that your heating isn’t on when it doesn’t need to be.
Field trials show 6% less gas used in homes with a smart thermostat.

More information on upgrading your heating controls:
Adding individual room temperature controls
Estimated heating bill savings

Back to home

bottom of page