Boiler thermostat

Most boilers have a dial, marked with either numbers or a scale from Min. to Max. This controls the temperature at which the water leaves the boiler. If it is not set high enough, your system may struggle to heat rooms to the desired temperature. However, if there are young children or vulnerable people in the household, ensure that radiators do not get so hot that they may cause a danger if touched. In most boilers, the boiler thermostat controls the temperature of water sent to both the hot water cylinder and the radiators. With ‘combi’ boilers, the temperature for the heating and hot water can often be set separately.

Programmer or timer

Programmers or timers let you set when you want the heating to be on. It is more energy efficient to only have the heating on when the house is occupied. However, remember that it will take some time for the house to heat up and that it will retain the heat for some time after the heating is switched off.

Therefore, factor in these warm-up and cool-down times when setting your timer. Remember, you can also turn your heating off when you go away on holiday. If it is very cold, leave on a low temperature just to ensure that the pipes don’t freeze.

If you have a standard boiler, your programmer will likely control the hot water as well. You can sometimes set the hot water times separately. It is best to set the hot water to only be on for as long as required to produce the amount of hot water you need. Experiment with reducing the amount of time the hot water is on each day to find the minimum amount of time it can be on whilst still producing enough hot water for your needs.

Types of programmer

There are two main types of programmer:

• Mechanical programmers usually have a set of sliders (called ‘tappets’) that you move around a clock face. You use these to set the times of day you’d like the boiler to switch on and off.
• Digital programmers display information on a screen. You can often set different time patterns for different days of the week.

Most programmers allow you to set the heating (and hot water) to turn on and off several times during the day. They vary in the degree of flexibility they offer. Some only allow a single setting which applies to every day of the week. Others allow you to set different times for weekdays and weekends. The most advanced allow you to set different times for every day of the week.

Room thermostat

A room thermostat allows you to set the desired temperature using either a dial or a digital display. The thermostat senses the temperature of the air around it and sends a signal to the boiler to switch off once the desired temperature is reached.

It is worth bearing in mind that you set the temperature of the area where the thermostat is located. If this is not your main living area, you may need to experiment with the setting to get the temperature in your main living area just right.

In terms of saving energy, it is best to have the temperature as low as possible whilst keeping the temperature in the house comfortable. Each 1°C reduction results in an approximately 8% saving in heating consumption. Be aware that this should never be done at the expense of health. It is recommended that main living areas are heated to at least 18°C. However, the very young, elderly and vulnerable may require a higher temperature.

It is important to remember that turning the thermostat up higher won’t make the building heat up any quicker. It will take the same amount of time to heat up but will then carry on getting hotter, making rooms too hot and wasting valuable energy.

Thermostatic Radiator Valves (TRVs)

TRVs are particularly useful because they can be used to control the temperature in each room (where a TRV is present). The higher the number selected, the hotter the radiator will get.

TRVs measure the air temperature and so should not be covered up or enclosed. Being boxed in behind a cupboard or covered by a curtain will restrict the TRVs ability to control the radiator.

TRVs can be set fairly high in rooms that are frequently occupied but can be set much lower in rooms that aren’t used for any significant period of time (e.g. toilets, utility rooms, spare rooms etc.). However, be careful that rooms don’t become so cold that condensation begins to form.

Just as with room thermostats, setting them higher won’t make a room heat up any quicker. It just means that the room will eventually become too hot, wasting precious energy.

Hot water cylinder thermostat

If you have a standard boiler, you will also have a hot water cylinder that stores hot water for hot taps and showers. A thermostat is usually fitted between 1/4 and 1/2 the way up the cylinder and is marked with a temperature scale. This should be set to 60°C which is hot enough to kill any harmful bacteria without using excessive energy.

If the water produced is too hot, you could consider installing a thermostatic mixing valve which will automatically ensure that hot water comes out of taps and showers at a safe temperature.