The water pressure in the heating system is also important. If the water pressure is too high or low, this can cause problems with your hot water and lead to your heating system breaking down. Check whether your pressure is still correct on an annual basis, and re-pressurize your heating system if necessary. Then you should bleed the radiators immediately afterwards.
Clicking, knocking or other sounds: bleeding your radiators
There should be no noises emanating from the radiators and pipes of your central heating system. If you can hear water flowing or clicking or knocking sounds, you need to bleed your radiators (opening them to release the trapped air). Another sign to watch for is when only part of the radiator is hot.
The correct water pressure
Look at the water pressure indicator on your boiler. If this is below 1 bar, the system needs to be topped up with water. You need to fill it until the water pressure reaches 1.5 bar. Make sure the pressures stays below 2 bar. If the pressure drops quickly again after being topped up, there may be a leak in the system. Please contact the central heating company.
How do I top up the pressure in the boiler?
- Unplug the boiler from the mains power supply and wait until the whole system has cooled down. This will take about half an hour.
- Set the thermostat to the lowest setting and turn on all the radiator supply taps.
- Locate the cold water supply tap. This will often be near the boiler (you can also use the washing machine supply tap). Connect the hose to the supply tap and tighten it firmly.
- Then connect the hose to the fill valve on the boiler, but do not tighten it. Leave it loose so that air can still escape.
- Turn on the supply tap slowly, and turn it back off if any water starts to leak out anywhere. Once the air is out of the hose, you can tighten it up properly.
- Then turn on the supply tap to the full extent.
- Turn the fill valve by a quarter turn. Proceed to fill the boiler until the pressure indicator reaches between 1.5 and 2 bars. Caution! The pressure must never exceed 2 bars.
- First close the fill valve on the boiler; then turn off the supply tap and unscrew the hose.
- After being topped up, the central heating system must be bled.
How do I bleed my radiators?
- Unplug the boiler from the mains power supply. Wait at least 10 minutes before you start. You do not need to wait if you have just refilled the boiler.
- Take the bleeding key and a cloth. Start with the radiator at the lowest point in your home. Then work upwards and finish with the radiator at the highest point.
- Insert the key into the vent valve which is located at the top of the radiator.
- Turn it to the left so that the valve opens slightly. Hold the cloth in front of the nipple of the vent valve.
- When water begins to come out of the nipple, you can close the valve again.
- Repeat the same process with all the radiators in the home.
- Reconnect the boiler to the mains power supply.
Water that comes out of the radiator will often be dirty. Make sure you keep a cloth or mop handy to clean the wall and floor.