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Central heating controls

A wall mounted room thermostat

Decent central heating controls will help you heat your home more efficiently and lead to lower energy bills.

If you understand how your heating controls work, you’ll save energy and money as you’ll be heating your home more efficiently.

This page looks at various types of heating control. Your system won’t have all of them, and you can jump to what you need to know using the links below:

Programmers or timers | Room thermostats | Hot water cylinder thermostats

Thermostatic radiator valves | Weather and load compensation | Smart heating controls

Programmers or timers

A timer or programmer allows you to control when your heating and hot water comes on and when it goes off.

Programming your heating

This means you can programme your central heating to fit around your needs. If you’re not at home or you’re in bed asleep, then the heating doesn’t need to be on.

Most programmers are wireless and digital (they have a little screen). Older systems may have a non-digital timer that works by moving ‘tappets’ (little plastic things) around a dial.

The trick is to set your heating to come on half an hour before you get home or get up, and set it to switch off half an hour before you no longer need it. This is because an average home takes around 30 minutes to heat up when the heating comes on and 30 minutes to cool down when it goes off.

Your programmer may also have the option of setting different on/off times at the weekend.

A well-insulated home warms up faster and cools down more slowly – meaning you can set the heating to come on later and turn off sooner, saving energy and money. Play with the timer to see what works best for your home.

Programming your hot water

Setting the hot water timing depends on the type of boiler you have. A combi boiler only heats up water when you turn on a hot tap, so you don’t need to programme it. But if you have a hot water tank, this will need to come on every now and then during the day.

The number of times it does this depends on how big and how well insulated the tank is, and how much water the household uses. Try an hour in the morning and an hour in the evening; if you don’t run out of hot water, then that’s enough – no need to spend more money than you have to!

Here are three films we made on different central heating controls. They’re quite old, but they’re still very popular …

How to use a digital central heating programmer
And here is one specifically on the Danfoss central heating programmer. (We made this because the Danfoss is the model that Bristol council has been installing in its own housing stock)
And here’s a film about using a non-digital programmer …

Room thermostats

Room thermostats are usually found in a hallway or sitting room. Their 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 between 18 and 21ºC. This is a comfortable temperature for most people. Some people need to keep their home warmer than 21ºC due to their age or health problems.

Some modern heating controls now combine the timer and the thermostat, allowing you to set different temperatures for different times of the day.

Hot water cylinder thermostats

Hot water tank/cylinder thermostats regulate the temperature of your domestic hot water by switching off the heat supply from your boiler once the set temperature has been reached. They can save you money and avoid wasting energy by over-heating your water.

If your hot water tank has its own thermostat, set it to 60°C: that’s hot enough to kill harmful bacteria like legionella, but not so hot that you’re wasting energy. If you find 60°C too hot, mixer taps can help.
Read more about hot water cylinders (including thermostats and cylinder insulation) here.

Thermostatic radiator valves

Thermostatic radiator valves (sometimes abbreviated to TRVs) allow you to control the temperature of a room by regulating the flow of water through the radiator.

If, for example, during the day you spend most of the time downstairs, you could set the TRVs on the downstairs radiators to medium or high and leave the upstairs radiators on low.

It’s not generally a good idea to turn radiators off completely for weeks or more, because very cold rooms can develop damp and mould. Instead, set the radiators in rooms you’re not using to low, and close the doors so that the heat from your warm rooms doesn’t travel there.

Close up of a thermostatic radiator valve
Thermostatic radiator valves control the temperature of a room by regulating the flow of water through a radiator.

Weather and load compensation

Weather and load compensation devices can help reduce the amount of energy used by your boiler by adjusting the boiler thermostat and therefore the flow temperature of the water in response to conditions either outside or inside your home.

A weather compensator monitors the temperature outside and will automatically reduce the flow temperature when the weather is mild.

Load compensators adjust the flow temperature in response to changes to the indoor temperature. When the heating first comes on, the flow temperature will be set higher to warm your home more quickly, but when the desired temperature has nearly been reached, the flow temperature will be reduced which will avoid overheating.

These devices work differently to room thermostats or thermostatic radiator valves which only affect whether the boiler is on or off, or water flows to an individual radiator.

The best option for you will depend on your individual needs and system set up, and we recommend you get advice from a heating expert.

Smart heating controls

It’s possible to control your heating system with an app on your smartphone or tablet. These allow you to turn your heating and hot water on and off or adjust the temperature from wherever you are, as long as you’re connected to the internet.

And there are advantages to being able to control your heating while you’re out. For example, your heating may be scheduled to come on at 5.30pm. But if you’re held up, you can use the phone app to tell the heating to come on later.

On some apps, you have the option of using GPS technology to turn the temperature of the home up or down, depending on whether you – or family or housemates – are in or out or travelling towards the house.

And some will respond to weather forecasts, so if, for example, some warm weather is on the way, the app will reduce the temperature setting of your heating.

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