Has your combi boiler lost water pressure?

When water pressure is lost it indicates that there is an issue with your boiler. Low pressure is fairly simple to identify as most boilers have a built-in gauge. Regardless of the pressure in our mains network, the plumbing arrangements for the water pipes in your home may substantially reduce that pressure by the time it gets to your taps. Losing pressure may be due to a water leak or expansion vessel failure causing damage to the pressure relief valve.

Constant water pressure is important to maintain the efficient functioning of your boiler system. Pressure in most modern combination boilers is maintained by the flow of cold water from the mains supply through a mechanism known as the ‘filling loop’. You may be able to manually regulate the amount of water circulating your radiator by using a filling loop, meaning you can re-pressurise your boiler. Check your boiler’s instructions to see whether you can re-pressurise your boiler yourself.

If you are able to manually re-pressurise your boiler you will generally have to follow these instructions; to begin the re-pressurising process, identify the filling loop and the pressure gauge. Next practice switching the boiler controls to off before attempting to top up the pressure. Ensure that the pressure gauge can be monitored while accessing the filing loop (the ideal pressure for any sealed system is 1.5bar). The filling loop should have a silver flexible tube with two handles; in the off position the handles will be across the flow of the pipe. You will be required to slowly turn them so they straighten up in line with the pipe. You should now be able to hear the water flowing through into the boiler. Carefully check the pressure gauge as it creeps into the green area or the 1.5 bar marker. Now turn the handles back to the original position.

Be careful if you decide to re-pressurise the boiler yourself, the biggest mistake you can make is over pressurising, this happens when you cannot monitor the gauge as you increase the pressure. Therefore if you can’t monitor the gauge yourself, get someone else to come and help you. If you continue to have pressure problems after you re-pressurise your boiler, contact us at McQueen Heating Ltd.