7 reasons why your boiler pressure is too high or low

boiler pressure too high or too low

Is Your Boiler Pressure Too High or Low? ⬆ ⬇

boiler gauge

Too much pressure in your boiler doesn’t sound good, does it?

You might have seen cartoons or other slightly less realistic TV programs where too much pressure results in the boiler exploding but it can’t be that serious, can it?

If your boiler is not working then it could be a simple pressure issue.

Whether you have a Worcester Bosch, Veissman, Ideal, Baxi, Vokera, Vaillant, Heat Line or any other boiler then they can all loose pressure with no alarming underlying issue.

Well while it won’t often be quite as serious as that if your boiler pressure is too high it will cause problems. Before we get into those it’s important everyone reading this knows what exactly pressure is in the boiler and why it is so important.

Boiler Pressure – The Basics

To simplify what pressure means it is basically the balance of water and air inside the boiler system this includes the pipes as well.  A balanced pressure is necessary if you want to heat the water that travels around your home.

If the pressure is too low or too high this won’t be possible and can cause a myriad of other problems.

In fact, pressure problems are one of the most common reasons people replace and upgrade their boilers.

Boiler Pressure Too High? – How To Read Boiler Pressure

You might be thinking “is your boiler pressure too high – how am I supposed to know” if that was your first thought reading the title don’t worry because reading the pressure is quite easy.

That’s what the pressure gauge on the boiler is for after all.

This gauge will often have numbers and colours so you can tell at a glance whether the boiler pressure is too high.

The green 1 – 1.5 bar is the safe spot where you want to be.

boiler pressure

If you are hitting over 2.5 then you have too much pressure and if you are below 1 you are losing pressure.

While gauges will go higher in most cases a boiler will shut off or breakdown before it reaches the 3 – 4 numbers.

However, if for some reason it hasn’t and it doesn’t lower after a while then you should shut the boiler off for your own safety.

If you do see higher numbers of the gauge don’t worry straight away especially if the heating is on.

If your boiler is busy heating up and someone is cleaning the dishes, someone’s taking a hot bath and you have your radiators on then the pressure will naturally be higher. Sometimes it might even hit the 3 – 4 zone on the pressure gauge.

Don’t worry though because this just means the boiler is currently experiencing a high water demand. Once people turn off the hot water and radiators cool down the gauge will return to the more comfortable levels.

However, if you are constantly seeing high-readings and you aren’t placing a higher demand on your water then what could the problem be?

Well let’s go back to the first question I asked “is your boiler pressure too high” if it is and there is no way it could be because of normal usage then it will likely be because of a fault let’s look at some of the common causes in more detail.  

Boiler Pressure Too High – What Could Be Causing The Problem? 

If your boiler pressure is too high then there could be multiple different causes sometimes these will be easy to fix and you can even do it yourself.

It could also be a much more complicated issue so let’s look at some of the common causes for pressure problems.  

Boiler Age

10 year boiler warranty

If your boiler is over 10 years old and you are experiencing pressure problems then there is likely a connection.

Boilers do naturally experience wear and tear and performance issues as they get older (don’t laugh) and will usually suffer from pressure problems.

So, in these cases upgrading to a new boiler is recommended repairs might patch the problem for a while but they aren’t going to be a long-term solution. If you need a new boiler, take a look at our guide to the best combi boilers on the market

Faults and Malfunctions 

There are numerous components in a boiler-related to measuring/ dealing with the pressure. If these get damaged in some way or malfunction then your boiler’s pressure could easily rise.

The pressure release valve and filling lope are the two most common culprits for this.

You can inspect these yourself but in the majority of cases calling in a professional is advised unless you really know what you are doing.

The good news is if the issue it quick and simple it might not cost much to fix although if you need replacement parts it will be more expensive.

Too Much Water

boiler leaking water

Can a boiler have too much water? Is your boiler leaking water? That might sound like a riddle but the answer is yes and if it does it can cause problems especially where pressure is concerned.

Ironically this problem often happens when you get your boiler depressurised because of problems if your boiler has low pressure.

But going from too little to too much is still a problem, isn’t it?

To diagnose this problem you simply shut the boiler off and see what the pressure gauge says, if it reads 1.5 or more then you likely have too much water in the system. But how do you remove it?

Thankfully this is again quite simple and in most cases simply bleeding your radiators will get rid of the excess water and return the pressure to normal.

It might sound painful but all you have to do is turn the safety valve a little on your radiators and let some excess water drip out. Monitor the gauge while doing this and stop when it reaches back into the safe green zone. ?

Boiler Pressure Too High – Error Codes ⬆

ideal boiler error code

Before you go and inspect your pressure gauge because this blog has probably made you a little anxious. You should know that many modern boilers will also run error codes on their control panels if they are detecting problems with the pressure.

So, keep your boiler’s instruction manual handy or be prepared to search online for it or call the manufacturer if you spot some error codes and think they relate to your boiler’s pressure. Error codes are a great way of catching a problem early that might not show up on the pressure gauge right away. Your boiler pressure may be high but this could be a simple fix. 

Boiler Pressure Too High – Is It Dangerous?

boiler overflow pipe leaking

If you skipped down to read this section first make sure you go back and read the rest!

Exploding boilers like I said earlier are pretty much the work of cartoons and dramatic movies.

High pressure doesn’t equal instant explosion.

In fact, most boilers that have too high pressure will shut down due to the pressure release valve or just break down because they can’t handle the stress (yeah we can all relate to that can’t we).

They will likely spring leaks and might soak your carpet or kitchen but there usually won’t be any huge explosion.

What should i do next?

boiler cover (service)

If your boiler is on the brink and you think that you need it fixing, contact UK Home Cover who provide boiler cover for UK residents.

Alternatively you may need a new boiler.

If you have a back boiler then we will struggle to help you but you may find out back boiler replacement guide helpful.

We can however help you if you require a combi swap or a system boiler conversion. 

We can offer boilers on finance or cash outright with a fixed online boiler quote within minutes.

We offer finance on a range of boilers from £9.50 to £17 per month.

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