How to Reduce Boiler Pressure in Combi Boiler UK

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Boilers having pressure issues are quite common, not that that makes it any better, as when your hot water and heating are lost, the frustration can be intense.

The good news is that it can be fixed.

Whether the boiler pressure is too high or too low, it is an issue that prevents your boiler from being able to effectively pump water around the pipes in your home. In other words, it is preventing you from warming up in the cold months or having your daily shower.

If you already know how to adjust your boiler pressure, but you are finding that the issue keeps recurring, it implies that there is a more serious issue with your boiler. In this scenario, it will definitely be worth speaking to a qualified Gas Safe boiler engineer to have a look at it and diagnose the culprit.

But if it doesn’t happen often, read on for more information on how to check, increase and reduce boiler pressure and to learn the common reasons why your boiler pressure might be a bit skewed.

What is the Ideal Boiler Pressure?

When you look at your boiler, you will see a gauge which measures the pressure in bars and a needle to indicate the current pressure level. Usually, pressure gauges for boilers give a reading between 0 to 4 bars.

Notice that there will be some numbers on the scale marked out with a green area indicating the optimal pressure value for your boiler. Normally this is between 1 and 1.5 bar.

Note: You can double-check the optimal pressure for your particular boiler model by reading the users manual.

You may also notice that there are numbers marked in red on both the lower and higher ends of the scale. These numbers indicate that the pressure is either too low or too high and could cause problems.

So, try to keep the pressure in your boiler within that green margin indicated and your pressure will be fine. However, if you find that it keeps going under even after adjustment, this could mean you are losing pressure.

If you need to reset your boiler too often, it may be a sign of a more significant fault, such as a faulty PCB, a central heating pump problem and if your boiler isn’t firing up for central heating or your boiler isn’t igniting, it may be time to consider getting a new boiler quote.

But what about if your boiler pressure is too high?

What if Your Boiler Pressure is Rising to 3 Bar?

As the ideal area marked on your boiler gauge is most likely to be between 1 to 1.5 bar, 3 bar is going to be way too high.

Most boilers have built-in safety precautions to shut themselves down at this point. Also, boilers will have an internal PRV (pressure release valve) and so if this component is working, having a high boiler pressure is not a danger.

What Should the Boiler Pressure Be When the Heating Is On?

Sometimes your boiler pressure might be only reading high when you have the heating on, and this can be normal, depending on how high, really.

If the pressure is between 1.5 and 2.5 bar it is nothing to worry about as using the heating will be putting more pressure on the heating system.

However, if you do find that it is consistently going over 2.5 bar into 3 or even 4 bar while you have your heating on, it would be wise to seek help from a professional boiler engineer to get it checked over.

Related boiler problems:

Causes of High Boiler Pressure and How to Reduce It

There are a number ways that you can reduce the pressure of your boiler but it’s not always simple as it depends on the variable causes and so the first thing you need to do is find where the problem lies:

Need to Bleed the Radiators?

There is a chance that your boiler has too much water in the system if you have had to repressurise recently after suffering from low pressure.

Before bleeding the radiators, it is best to check that the filling loop is secured so that no water is entering the system. Also, ensure that your boiler is turned off and has cooled down and be sure the water that comes out of the radiators when you bleed them has also cooled down!

Find a radiator key or a tool that is suitable to use on the water valve of your radiator which will be located on one of the upper corners, and slowly turn the valve anti-clockwise.

Release only a small amount of water from each of the radiators before returning to your boiler’s pressure gauge to check to see if the pressure has now corrected itself (it should be below 1.5 bar when switched off).

If it is still too high, repeat the process of bleeding small amounts of water from the radiators and checking the pressure gauge until it has reached a suitable pressure reading.

Is your boiler losing power? Or is your boiler leaking water? If your boiler is old, past its warranty, it may be time for a new boiler replacement.

Is Your Boiler Also Leaking?

A loss of pressure may also be caused by a leak somewhere in the system. These are usually pinholes in radiator pipes that gradually cause a loss of pressure. But sometimes, it may be the result of significant corrosion of major boiler components.

The problem with this is, it means that pipes and components may need replacing and so this is something you will not be able to fix yourself.

In any case, it is often not the most economical decision to just replace parts, and a boiler replacement may be the best option available, but this does depend on the situation.

Boiler brand faults: 

Don’t Risk Home Repairs!

If bleeding the radiators has not worked and you may or may not have a leak, there is a possibility that the boiler has faulty components or something else wrong with it that required a much more in-depth check.

The wisest decision would be to speak to an engineer so that they can diagnose the exact problem and see what can be done and whether a replacement is the most viable and economical option for you.

With that being said, if your boiler is 8 years old or over, it may be time to think about getting a replacement anyway, as a new, modern boiler model is likely to be more energy-efficient and so will save you money over time.

Not only that but they tend to come with extended warranties, making the occurrence of this happening again, much less stressful!

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