Understanding central heating

Gas boiler controls

Gas boiler controls will vary across our homes, depending on when the boilers were installed. They will all have the same functions, but the controls themselves may look a little different. All boilers will have a time clock by which to set when your radiators come on.

Setting the time

Turn the whole dial clock wise until the clock hands show the correct time. The black triangle should also point to the correct hour.

Setting the heating

Push the tappets to the inside of the dial to set the times that you want heating. Each tappet amounts to about 15 minutes of heat.

Put the time clock in control

There is a dial with a radiator symbol. Turn this to the image of a clock. Your heating will now come on at the times you have set on your clock.

Setting the thermostat

All of our houses have a thermostat. This will either be mechanically or electronically operated depending on when it was installed.

Set the right temperature

You should set the temperature in rooms where you spend most of your time to 21°C, and 18°C for rooms where you spend less time. You should avoid turning the thermostat beyond 21°C if you are cold. You should instead keep the heating on for a little while longer. If you turn the heat up it will rapidly be lost when you turn the heating off. Keeping the heat on for longer will build heat in the home for a longer period.

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Thermostatic Radiator Valves (TRVs)

The best way to control the temperature in your home is to lower the temperatures of your radiators. Many of our homes will have radiators that are fitted with TRVs. To use these you simply turn them. Turning to number 5 means you fully open the radiator valve and the temperature goes up. To turn them down, you turn the TRV in the opposite direction towards 1.

Using TRVs effectively

In rooms you don’t use frequently you should turn the TRVs down to 1. You should also keep the door closed. You shouldn’t turn the TRV to 0, as this will mean the room is not heated at all. Cold rooms attract moisture from warmer rooms. This could lead to damp patches forming.

What does the * mean on a TRV?

Your TRV will have a * between the 1 and the 0. This is actually a frost protection device. If you decide to switch the radiator off, you should set the * function rather than the 0. If the room comes close to freezing, the TRV will allow the radiator to warm a little. This will only happen if the heating is actually turned on in the rest of the house.

How the does the TRV know when it’s freezing?

Inside the valve is a ring of wax which changes shape when it is hot or cold. At close to freezing the ring of wax contracts a little, which allows some heat to come into the radiator. The radiator won’t warm the room to any great extent, but will probably achieve a temperature of between 5°C and 10°C.

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