Understanding how your radiator thermostat works helps ensure your home is kept at a comfortable temperature, while maintaining control over heating costs. Efficient use of heating controls also benefits the environment, because you waste less fuel or heat.


Whether you have a gas, LPG or oil-fired central heating system, your controls are likely to include a boiler thermostat, a programmer or timer, thermostats for the rooms and thermostatic radiator valves (or TRVs).


Room thermostats

These control the temperature in a particular room, ensuring it does not get warmer than needed. Once the requisite temperature is reached, they turn the heating off until the room temperature falls.


It's important that room thermostats are not blocked by furniture or curtains, because they need to be exposed to the air in the room in order to determine the temperature.


Ideally, each room should be set to the lowest comfortable temperature - for most people this lies between 18 and 21 degrees.


Even if it is colder outside, the thermostat will ensure the room heats up to the desired temperature - although it may take a little longer to do so in winter months.


You can set the temperature to vary at different times of day.


In order to control the heat in each room, you will need to install thermostatic radiator valves.


Thermostatic radiator valves (TRVs)

These work by controlling the flow of water to a radiator when it gets too hot.


It's important not to use radiator covers, as they confuse the thermostatic sensor - making it believe the room is warmer than it actually is.


You can still use TRVs even if you have un-removable radiator covers. You can simply turn up the TRV if the room is not warm enough.


Hot water thermostats

Your hot water thermostat controls how hot the water gets, saving you energy and money. When the desired temperature is reached, the boiler is switched off.


How hot?

Cylinder thermostats are fitted to the side of the boiler and should be set at between 60 and 65 degrees. This temperature will not scald, but it will kill dangerous bacteria.


Combi boiler systems do not feature cylinders. In most cases they have their own thermostats.


Boiler thermostat

Your boiler thermostat will probably take the form of a dial with numbers or 'min' to 'max'. This controls the temperature of the water being sent to the property's radiators. The higher you turn up the heat, the faster your home will heat up. Indeed, on a cold winter's day you may well need to turn the boiler up higher in order to attain a comfortable temperature.


Normal boiler with hot water cylinder

If your home is fitted with a normal boiler and a hot water cylinder, the boiler temperature should be set higher than the cylinder thermostat. If you do not do this, the hot water cylinder won't reach the desired temperature. Combi boilers usually have two dials. The first features a radiator symbol, and manages the temperature of the water going to the radiators. This thermostat does not impact the temperature of the water used for showers and baths etc.



Programmers - or timers - let you control when the heating and hot water come on. It can be set to go off when you're in bed, for example. Most modern programmers have different dials for water and heating. You may need to modify your settings when the clocks go back or forward.


It's important to know how long it takes for your home to reach the desired temperature, and how long it takes to cool down. On a cold evening, time how long each takes, then set your thermostats accordingly. For example, if it takes an hour for your home to heat up, set the heating to come on an hour before you wake up. Equally, set the timer so your home is about to cool down when you go to bed.


Programmable TRVs

These are like regular TRVs, but they allow you to program when the heating goes on and turns off.


Optimisation systems

These systems determine how long it takes your home to warm up, then starts the heating in order for the house to be warm by the time you wake up. If, for instance, you get out of bed at 8am and it takes 45 minutes for the desired temperature to be reached, the Optimisation system will start heating your property at 7.15am.


The advert of smart heating controls

The rapidly changing energy market has introduced a number of innovations in recent years, including smart controls. These systems allow you to control your heating remotely using a mobile phone, tablet or computer. Some of these systems remember the settings you normally use, while others harness automation technology in order to optimise when your heating comes on - saving you money, and ensuring your home is warm when you come home. The settings can be modified if your plans change.


Are smart heating controls right for me?

Whether or not you choose to use smart heating controls depends on how you manage your heating presently - and if you like the idea of controlling your heating with an app.


Smart heating benefits

  • Save money with more efficient use of your heating system
  • Convenience - your heating will come on automatically depending on your schedule
  • Control the temperature of particular areas of your home - and individual rooms
  • Lower your carbon dioxide emissions


Do I need to get a new boiler if I invest in smart controls?

No, smart heating controls can be installed in your home without the need to replace your boiler.


Automated heating

This innovation only turns the heating on when someone is at home. They track your smartphone's location or use sensors to do this. They can also switch on the heating when you start moving towards home. Automation is often used in conjunction with smart heating controls.