My boiler has lost water pressure. What can I do?

By Energy Company Numbers on February 15, 2023 in Help and advice

Whilst many consumers don’t fully understand the issue of water pressure in boilers, they know enough to become concerned when the needle on the dial drops unexpectedly. Loss of water pressure is a symptom that there are problems with your boiler – or more likely, your pipework. Don’t panic. In some cases it is easy to fix yourself.

Water pressure and your boiler

Your boiler needs constant water pressure in order to function efficiently. In most modern combination boilers, this pressure is maintained by cold water flowing straight from the mains cold water supply through a mechanism call the ‘filling loop’. The pressure drops for a number of reasons. One cause can be leaks in the system. They may not be big leaks, but over time they can cause problems. It is also possible to lose pressure when you bleed your radiators. Combi boilers can become a real headache if your system has minor leaks.

Top tip: If you are having problems with you boiler, call your energy supplier immediately. Most will help you with a one-off boiler repair or service plan.

Any leak in the systems of pipes and joints will affect pressure, and if they are very minor leaks the water may evaporate or dry before you have time to find them. If joints are hidden away in walls or floors it can be a real problem to detect them. A traditional boiler will just keep topping water levels up automatically, so minor leaks are not such a problem.

Checking your pressure gauge

Make sure you check your pressure gauge regularly, so that you are aware of fluctuations. The gauge is usually on the front of the boiler. It should read about 1 bar, for a majority of boilers. If the boiler pressure drops below 1 bar it will not fire up.

A red indicator needle sometimes indicates this, which is set when the boiler is first installed. If you notice fluctuations keep checking the gauge regularly. A drop in pressure is a sign you may need to call an engineer.

But first, check the user manual that came with your boiler. You may be able to re-pressurise the boiler yourself. The instructions may be on the reverse of the boiler control panel. If this panel needs tools to remove it, don’t attempt it yourself.

Call an engineer. If you re-pressurise the boiler yourself and the problems persist, call the engineer rather than trying to diagnose the problem yourself.

Don’t take risks with your boiler – take action as soon as you can if your own re-pressurising measures fail.

About the Author

Energy Company NumbersView all posts by Energy Company Numbers
Energy Company Numbers is a telephone number directory service dedicated to helping UK consumers keep in touch with their energy suppliers.


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