Is your central heating system dropping pressure? You might have a hidden leak!

Boiler pressure too high? Here’s how to fix it

No one likes being under a lot of pressure, and your boiler is no different. A small increase in boiler pressure is completely normal, but if there’s not enough air in the expansion vessel, the system could become over-pressurised.

In this article, we are going to explore what your boiler pressure should be, how to spot if your boiler pressure is too high, and what to do to fix it. So, without further ado, let’s get into it.

What pressure should my boiler be at?

‘Boiler pressure’ means the balance of water and air within the boiler, and the force that water gets pushed through the pipes. The boiler pressure needs to stay at a reasonable level to ensure that your boiler is gas safe and working efficiently.

Your boiler pressure should be between 0.5 to 1 bar when the heating is off, and 1 to 1.5 bar when the heating is on. When checking the pressure of your boiler, make sure your heating is on to ensure that your reading is accurate.

How do I know if my boiler pressure is too high?

As we mentioned, your boiler pressure should be between 1 and 1.5 bars when your heating is on. One of the easiest ways to see if your boiler pressure is too high is if the pressure gauge is showing more than 1.5 bars. 

If you don’t continually sit in front of your pressure gauge to monitor it (which is totally reasonable), another sign of an over pressurised system is a system shut down. Of course there are other reasons for this to happen, but high pressure could definitely be a potential cause in the event of a shut down.

Another way to tell if your boiler pressure is too high is a leak in the system. These leaks would usually occur at the weakest spots, such as where the pipes join your radiators. So, if you notice any signs of water escaping, it might be worth checking your boiler pressure.

Why is my boiler pressure too high?

There are multiple causes of high boiler pressure. For example, if you’ve recently had to repressurise your boiler because its pressure was too low, you could have added too much water. This is a common mistake, especially if you repressurised your boiler while your heating was off. Make sure you keep an eye on the pressure gauge to know when you’ve added the right amount of water, but keep in mind that the pressure naturally increases when the boiler is on.

Alternatively, the filling loop, opened to allow water in when your boiler pressure is too low, may have been left slightly open. This signifies that new water is entering the system.

If you don’t think either of these issues are the culprit, your high boiler pressure could be as a result of one of the parts not working correctly. The pressure relief valve (PRV), for example, could have a leak or not close properly, stopping it from releasing water when the pressure in the system becomes too high.

What happens if your boiler pressure is too high?

Most of the time, having high boiler pressure isn’t dangerous. Your PRV valve should trigger and start releasing water, or your boiler should shut itself off. However, you shouldn’t rely on these safety precautions, and high boiler pressure shouldn’t be ignored.

How to reduce the pressure in my boiler?

Before you attempt to reduce the pressure in your boiler, you need to determine the route of the problem. Start by checking that the filling loop is completely closed. If it is, but your boiler pressure is still too high, a heating engineer may want to investigate the PRV to see if it’s stuck. 

Once any issues like these have been fixed, you can start to take the necessary steps to release pressure from your boiler. One thing you can try yourself is bleeding your radiators.

How to bleed your radiator

To do this, you will need your radiator bleed key, a bucket to catch the excess water, and a dry cloth or towel. Make sure that your heating is off and that your radiators have cooled down fully before attempting this, or else you may scald yourself. 

Once you have released a small amount of water from your radiators, close the valves and check your boiler pressure until it is at the correct level. Keep an eye on the pressure for the next few weeks. 

If your boiler pressure continues to increase, call a plumber. They will be able to inspect the boiler system and check if there are any issues and advise whether you need to replace your boiler.

How Harmuns can help

At Harmuns, we find and fix the leaks your plumber can’t. If your boiler pressure is too high, and your heating engineer suspects a leak but can’t find it, give us a call!

We will send an experienced, gas-safe engineer to your home to deal with the issue in the most efficient way. They will use a range of different equipment, such as moisture metres, thermal imaging and trace-gas systems to locate the source of the issue and fix the leak.

You may not need our services right now, but you could in the future. Save our number now to prevent future panic: 01753 378569

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About Harmuns

We are a specialist non-invasive pipe and water leak detection company here to fix your problems. We find hidden leaks on central heating systems, water mains and hot & cold water supply within the property.

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