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What should I do if my boiler is losing pressure?

What should I do if my boiler is losing pressure? It’s a question that we have been asked so many times over the last few years so we have decided to write a blog post on it.

When a boiler stops working it is a massive inconvenience to us all and one reason why a boiler doesn’t fire up your central heating is that it is losing pressure.

In this post, we will take a look at some of the things you can do to fix your boiler yourself if your boiler is losing pressure. We will also discuss when you may need your boiler repaired or a new boiler installation.

What is Boiler Pressure?

Before we get started, you will need to know what boiler pressure is and why it’s important.

Your boiler works by warming up the cold water in your home and then sending it throughout the pipes in your home to where you need it most. This could be the bathroom, kitchen, to your radiators and anywhere else you need warm water.

For your boiler to push this water around your home, it needs pressure to do so. Without this pressure, your boiler may not turn on and you won’t have warm water in your home. In modern combi boilers, this pressure is adjusted by something called a filling loop.

If you take a look at your boilers user manual you should see what your filling loop looks like. This is important because knowing what your filling loop looks like will allow you to repressurise your system later on.

Reason 1 for your boiler losing pressure – Water leaks in the system.

Depending on the brand of your boiler, the pressure in your system should be between 1 and 1.5 bars. If the pressure levels are below this your system won’t fire up. The majority of the time if your boiler is losing pressure it will be down to a leak somewhere in the system.

This could be a leaky valve, in your pipes or radiators or even the boiler itself. To identify if a leak is forming you can check to see if there are any damp patches in your home on the ceilings or walls. This will usually indicate that there is a leak in the heating system.

If you can’t find a leak it doesn’t mean that it isn’t there, it could be the leak is occurring in a place where you can’t see such as behind the boiler or under the floor.

Detecting a water leak is difficult and if left untreated it will cause damage to your home and it could also have health implications as it could cause mould to grow. The majority of the time leaks will occur at joints or fixtures, so if you suspect a leak you should check there first.

If you can’t find a leak on your own, give us a call and we can help.

Reason 2 for your boiler losing pressure.

If you have recently bled your radiators the pressure in your system will have dropped below the 1 bar threshold. This pressure drop occurs because you are letting air out of your system due to your radiators not heating at the same temperature at the top and bottom of them.

Thankfully this problem is easy to fix, all you need to do is find your filling loop and open it up until the pressure in your system returns to the recommended pressure in your boilers manufacturers handbook.

When you have filled your pressure back up to the recommended value you will then need to close the filling loop to stop excess pressure from building up as this can also cause leaks in the system.

Reason 3 for your boiler losing pressure- Faulty release valve.

Boilers have a release valve in them which is used when too much pressure is in the system. If this valve becomes damaged it will cause your boiler to leak water and as a result, your boiler will lose pressure.

If your release valve is faulty this isn’t something you will be able to fix yourself and you will need a qualified Gas Safe engineer to repair your boiler.

Reason 4 for your boiler losing pressure – Faulty parts.

For your boiler to work it needs multiple parts to function if any of these parts becomes corroded or damaged in any way then your boiler will lose pressure. Unfortunately, there are many parts to a boiler so you will need a heating engineer to come out and examine your boiler.

A heating engineer can then tell you what is wrong with your boiler and if it’s worth repairing or getting a new boiler.

Is low boiler pressure dangerous?

Rarely is low boiler pressure dangerous, it simply lacks the pressure to push the water around your home to your taps. However, as a boiler uses gas and Carbon Monoxide poisoning is very dangerous we always recommend that if you have any problems with a boiler that you should consult with an expert Gas Safe registered heating engineer.

The Majority of the time, your boiler will turn itself off when you have low boiler pressure and it will give you an error code to tell you why.

Worcester Bosch Boiler losing pressure.

Worcester Bosch boilers are reliable boilers that are very efficient, but they can still break and lose pressure. Typical error codes you will see if your Worcester Bosch boiler is losing pressure are:

  • E2,

  • A1,

  • CE 207,

  • H07,

  • 224 V,

  • 1017W,

  • 2970 B,

  • 2971 B.

Vaillant boiler losing pressure.

Once again Vaillant boilers are reliable and efficient boilers but they can still lose pressure. Error codes you will see if your Vaillant boiler is losing pressure are:

  • F.24,

  • F.12,

  • F.22,

  • F.73,

  • F.75

Baxi Boiler losing pressure

If your Baxi boiler is losing pressure you should see one of the following error codes:

  • E28,

  • E119,

  • 118,

  • 119,

  • H.02 – 06,

  • E.02 – 7,

  • E118

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