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What does the central heating programmer do?

What does the programmer do?

The programmer tells the boiler when to be turned on or off. You can set it to activate the boiler during different parts of the day and, if you wish, different days of the week (meaning you can have the system do different things at weekends to weekdays, for example).

During the times that the boiler is turned on, it will provide you with heating or hot water if requested by other controls, such as a thermostat (see below). However, during the times the boiler is turned off, it will not be able to provide heating or hot water – even if asked to by other controls. If you have a hot water cylinder you should also have the ability to set time control for your hot water – either within the programmer or through a separate timer. Ideally this should allow you to set different on and off times for your hot water compared to your heating.

The programmer often has a ‘boost’ function, which will let you operate the heating for a short time when it has been turned off. This is especially useful if, for example, you come home after a cold day but there is some time until the boiler is due to turn itself on. At the end of the ‘boost’ period, the boiler will automatically turn itself off. How should I use the programmer?

It is recommended that you set the programmer to turn the boiler on and off at times that suit your lifestyle. After all, there is little sense in heating the house and generating hot water all day if there is nobody at home. (One exception to this rule is if you are using the system for frost protection while on holiday, in which case the thermostat must be set to a low temperature.)

When setting the programmer to turn the boiler on in the morning, think about the time you usually get up, how long your house will usually take to heat up, and the weather outside. This will help you work out roughly when your heating system needs to get going.A good time to try is around 30 minutes before you usually wake up. If the house is not warm enough for you, extend this time, and at times when the weather is warmer outside, reduce it.

Your programmer should allow you to set a series of programmes throughout the day (for example, turning the boiler off when you leave the house in the morning, but turning it on again before you return home of an evening).Tip: Setting the heating to come on later when you know you will be late home will save you money.

If you have a hot water cylinder, your boiler will need time to heat the water inside it to give you hot water when you need it. This can take anything up to two hours so, if you use a lot of hot water in the mornings, you should bear this in mind when setting the programmer. The thermostat inside the cylinder (see below) will turn the boiler off when the water is hot enough. If you have a programmer that allows you to set different timings for the heating and the hot water, then it may be worth setting the hot water to come on an hour before the heating, so that the boiler can deal with one at a time. Tip: If your programmer cannot set different times for heating and hot water then you should re-programme it in the summer, when the heating is off, so that the boiler only runs long enough to satisfy your hot water needs. The programmer can seem daunting at first but by taking time to get used to its control functions you will be able to get the most out of your system – and be comfortable when you have to make changes to the programmes.


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