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Timer / Programmers

Picture of central heating timerThe timer / programmer allows you to control when your heating and hot water comes on and when it goes off.

You should set your heating to come on half an hour before you need it and set it to switch off half an hour before you no longer need it. This is because an average home takes around 30 mins to heat up and 30 mins to cool down when it goes off.

Your programmer may also have the option of setting different on/off times at the weekend or twice during the day. Ideally you should run the system in two periods and for no more than nine hours per day in total.

What do all the different settings mean? A heating controls jargon-buster:


Setting Means
AUTO / TWICE The heating will go on and off during the day at the times it has been programmed to do so
24 Hours / ON The heating stays on all the time
OFF The heating remains off all the time
ALL DAY / ONCE The heating will switch on at the first on setting and remain on until the last off setting
BOOST / + 1 HOUR The heating comes on for one hour of heat
ADVANCE Moves the programmer to the next on or off setting


Here are the links to a Youtube video and the user manuals for the most common types of timers / programmers we install:

Room thermostats

Picture of a room thermostatA room thermostat is usually found in a hallway, sitting room, stairs or landing areas.

Its job is to monitor the temperature in the house and send a signal to the boiler telling it to switch off when the house is warm enough. Thermostats are normally set at between 18 and 21ºC.

You don’t need to turn your thermostat up when it is colder outside: the house will heat up to the set temperature whatever the weather.

Thermostatic Radiator Valves (TRV’s)

Picture of a TRV on a radiatorTRV’s allow you to set the temperature of a specific room by controlling the flow of water through the radiator.

TIP - Save money by not overheating parts of your home that are unoccupied or need lower temperatures for example bedrooms or rooms not in use.

British Gas have a helpful TRV video guide on their Youtube channel.

Boiler Thermostat

Picture of a boiler and boiler controlYour boiler will usually have a dial on it marked in numbers from 1–6 or Min to Max.

This sets the temperature of the water that will be pumped from the boiler through the radiators to heat your home. The higher this is set the quicker and more effectively the system will heat your home.

Cylinder Thermostat

Cylinder thermostats control the temperature of your hot water by switching off the heat supply from your boiler once the set temperature has been reached.

They have a temperature scale marked on the thermostat and should be pre-set at between 60ºC and 65ºC.

Once set it is not recommended these controls are changed and they should never be set below 60ºC to avoid the risk of Legionella related diseases. 

More information

Energy saving trust logoThe Energy Saving Trust website has lots more information about your heating system and its controls.

If you have any further questions, please contact our Energy and Climate Change Team.


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