How to fix a boiler that is losing pressure

Discover everything you need to know to fix a boiler that is losing pressure, including why this problem happens in the first place.


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If your boiler loses pressure, it becomes far less energy-efficient, costing you more money. In some cases, it shuts down completely.

Thankfully, it may not take too much effort to fix a boiler that is losing pressure, once you know what to do.

How to spot when a boiler is losing pressure

This situation is most likely to come to your attention when your hot water stops working.

After all, most boilers have a system to detect when the pressure is too low, which shuts it down and stops it heating water altogether.

To confirm that your boiler has shut down due to low water pressure, check its pressure gauge.

If the gauge needle is between 1 and 2, this is normal. If it has dropped below 1, you can be sure that low pressure is the problem that needs to be addressed.

If it has risen above 2, it could well be that the pressure is too high. Most boilers will shut down in this situation too.

Why is my boiler losing pressure?

In most cases, your boiler has lost pressure due to a leak.

Your first task should therefore be to look for this leak around your home. Start with the pipes, radiators and the boiler itself.

You should never look inside the boiler though, as this could be dangerous. Although it may be possible to repair some basic leaks, it’s often best to leave these jobs to a Gas Safe registered engineer.

If you have recently bled the radiators, the pressure drop may have occurred as a result of this. Either that or the pressure may have simply decreased steadily over time, which is a completely natural occurrence. In either of these scenarios, the problem will be solved once your boiler is repressurised.

What should I do if my boiler loses pressure?

It may be possible to repressurise the boiler yourself.

The process for doing this differs depending on the boiler system, so check the manual for instructions. The instructions may also be attached to the boiler’s control panel or included on the manufacturer’s website. If you’re not sure how to repressurise the boiler safely, leave it to a Gas Safe engineer.

If the low pressure was caused as a result of a leak, it will continue to occur until that leak is fixed. So, if your boiler shuts down due to low pressure more than once, you’ll need the leak to be located and repaired.

A Gas Safe engineer will be able to diagnose the problem and the solution. In some cases, it’ll just require the leak to be fixed. In others, your boiler may need replacing or repairing.

Is low boiler pressure dangerous?

Low boiler pressure will not cause danger to you or your boiler. However, you will suffer financially from a heating system that is no longer cost-effective, plus you’ll have to deal with the stress of a boiler that keeps shutting down.

As such, this is a problem that you’re best off addressing as soon as possible.

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