Why Is My Boiler Pressure Dropping?

Modern boilers are much more reliable than older models, but they are not immune to faults or breakdowns.

Low boiler pressure is one such problem. If not dealt with, low pressure can cause chaos in your heating system - no hot water or central heating, for one thing. In the worst cases, it could mean that your boiler needs replacing outright.

M J Burt are the South’s property maintenance specialists, with over three decades of experience repairing boilers, plumbing, and other home fixtures. In this guide, we explain why boiler pressure drops, what you can do about it, and when to call in the experts.

What is boiler pressure?

Put simply, boiler pressure is the amount of water in your heating system at any time. The higher the pressure, the more water in your system.

You can usually tell the current pressure of your boiler by looking at the pressure gauge on the front. A boiler that is currently switched off should have about one bar of pressure, while a boiler that is heating your house should be around one to two bars.

Why does boiler pressure lower?

Low boiler pressure is usually caused by one of two things:

• Leaks: A leak will cause the water in your boiler to slowly drip out, reducing its overall pressure. To see if you have a leak, carefully check the pipes and flooring around your boiler and radiators for signs of dampness.
• Bled radiators: Bleeding your radiators (aka releasing the air trapped inside your heating system) will cause the pressure in your boiler to drop slightly. This air must be replaced with water to get the pressure back up again.

How do you raise boiler pressure?

If your boiler’s low pressure was not caused by a leak, you can usually raise it yourself.

Make sure to turn off the boiler before taking any steps. After the water has had time to cool down, connect a filling loop to both the boiler and the mains water valve, then open the valves to let fresh water into the system. Close the valves once the gauge is at one and a half bars. Turn the boiler back on and remove the filling loop - some systems may require you to press ‘reset’ before they will turn back on.

When should you call in a professional?

If your boiler pressure continues to drop even after you’ve refilled it, it’s probably a sign that your boiler has a leak or underlying problem that can't be dealt with on your own. That’s when it’s time to call in the experts.

Talk to the boiler repair specialists

The team at M J Burt have surveyed and repaired thousands of boilers over the years. After you get in touch with us, one of our Gas Safe-registered engineers will visit your home to diagnose whatever problem is causing your boiler pressure to drop. They will then be able to repair the problem, using their expertise and specialist equipment to get your boiler back to normal in no time.

Get a quote online or by calling our friendly team on 01202 721955!