< Back to guides

Boiler Pressure

Is Your Boiler Pressure Too High Or Low?

When it comes to making sure that your boiler is kept in tip-top shape and functioning efficiently, it can seem overwhelming.

Even if a boiler is relatively new, there are still things that can go wrong every now and again, usually through no fault of our own.

Fortunately, the majority of boiler issues are easy to solve and don’t involve you forking out for a new heating system straight away.

Have you noticed your boiler is turning off unexpectedly? Or, are you unable to turn it on at all?

This may be down to your boiler pressure. Without the build-up of water pressure inside your boiler, it simply won’t be able to heat water. On the other hand, if there is too much pressure, your heating system will also fail.

boiler pressure

No hot water means cold showers and a chilly home - everyone’s worst nightmare.

Don’t panic though. Keeping on top of the pressure of your boiler is really not a difficult task, once you understand how to identify any potential issues. Luckily, most of the time you don’t need to be a trained engineer to notice when your combi boiler pressure is out of whack.

It’s important to remember that if handled the wrong way, a boiler can be a dangerous appliance. Always take extra care and ensure you don’t touch internal components and pipes. Doing so could result in serious injury or death.

If you’re ever in doubt, contact a professional.

First things first, what is boiler pressure?

All boilers need the right amount of pressure to operate safely and effectively. If it’s not at the right level, your boiler won’t have the ability to do its job properly. Boiler pressure is measured by a pressure gauge, usually situated inside a panel or underneath your boiler. We’ll discuss the ideal amount of boiler pressure in the next section.

Whilst problems with the pressure of your boiler tend to be easy to diagnose and fix, it’s best to tackle any issues as soon as they crop up. Most pressure issues won’t stop your boiler from working completely, but you don’t want to risk it cutting out mid shower!

How can you check the pressure of your boiler?

Most combi and system boilers these days will have a built-in pressure gauge, so you can easily keep a check on your pressure levels. Your gauge may display pressure using a dial (a hydraulic pressure gauge) or, if you have a modern boiler installed, it’s probably a digital version. Either way, there will be a clear display of any warnings when your boiler pressure appears abnormal.

Don’t get straight on the phone to your engineer if you see your pressure changing temporarily as this is completely normal. Combi boiler pressure increases when the heating is on as your boiler uses fuel (gas, oil etc) to heat the water - this increase in pressure is natural. If your boiler is behaving as it should, the pressure will stabilise again once the system is switched off and cooled down.

Here’s a rough idea of the fluctuations in boiler pressure that you really don’t need to spend time worrying about…

  • 1 to 1.5 bars on your pressure gauge ⇨ normal pressure level when your central heating is switched off.
  • Around 2 bars ⇨ normal pressure level when your boiler is active/heating up.

Do your pressure levels match the above? If yes, great! There’s no need to be concerned.

If not, and you have noticed your central heating cutting out unexpectedly, your pressure levels are probably below 1 bar (too low) or around the 3 bar mark (too high). Don’t start scouring the internet for a boiler replacement just yet though, as fixing your pressure levels can be simple.

Worcester boiler pressure

Here at BOXT, we stand by the idea that, when it comes to boilers, you should always choose those that are proven to be as long-lasting and worry-free as possible. You have probably heard of Worcester Bosch boilers and rightly so, as they have been recognised as the best brand in the boiler world.

Opting for a quality boiler like Worcester Bosch, or another big brand, really helps to reduce the risk of any future faults cropping up - boiler pressure being one of these.

Despite the fact they are the most popular boiler brand in the UK though, Worcester boiler pressure may still fluctuate. So, it’s important to be fully clued up on the steps to take if you notice your boiler pressure is too high or too low.

Let’s take a look at how to look after your combi boiler pressure and keep your boiler happy and healthy.

Is your boiler pressure too high?

There are a few reasons why your pressure might be too high.

  • Have your pressure valves come loose?

Firstly, check that the pressure valves, usually found underneath your boiler, are closed tightly. Even if the valves haven’t been used recently, they may have come loose or been knocked accidentally.

  • Do your radiators need bleeding?

The next trick to have a go at is bleeding radiators. Although this is an easy task, you may want to call out your engineer as the water can be boiling and potentially dangerous, especially if there are kids or pets around.

Firstly, identify any radiators that make funny noises when warming up or those with cold patches on their surface. Turn your heating off and allow plenty of cooling time, before using a radiator key to open each valve and release any trapped air. This air should be released in its entirety. If your pressure then drops too low, you’ll need to top up the system pressure accordingly.

Is your combi boiler losing pressure?

Is your boiler pressure too low or has it notably decreased? There are a number of reasons why your boiler may be losing pressure.

  • Is there a leak?

Take a look around your home for any damp patches. A leak will cause the pressure to drop but, once you’ve spotted the source, they are easy to fix with the help of a professional. Sometimes, a leak may occur inside the boiler itself, in which case you should ask an engineer to take a look for you instead.

  • Have you bled your radiators recently?

Whilst bleeding your radiators every now and again is important, doing so will cause your combi boiler pressure to drop. Again, this is normal - unless the pressure fails to level itself out again.

Re-pressurising your boiler

If you’ve tried everything and your boiler still isn’t happy, it probably needs re-pressurising. This is a job you can easily do yourself by following these steps:

  • First off, make sure your boiler is turned off and completely cooled down.
  • You’ll then need to attach the filling loop. Different boilers require different methods here, however. Most boilers have a keyless filling loop, which will simply require you to pull a switch to add more water to your system. Others have a filling loop that resembles a hose, which is connected tightly to the two valves of your boiler. If you are unsure about the kind of filling loop you boiler has, check your boiler manual.
  • Depending on your boiler type, you can open the valves to allow cold water from the mains to fill the boiler.
  • You should allow the boiler to fill up until your pressure levels appear normal and, hey presto, your boiler will be re-pressurised.
  • All that’s left to do is give your boiler a quick reset and prepare to have a cosy home.

Noticed that your boiler pressure keeps dropping or your boiler pressure keeps rising?

Sometimes, problems with boiler pressure are (sadly) more serious. Even the big brand and high-quality boilers can have their faults, so if you have noticed that your Worcester boiler pressure is continually wreaking havoc, it is worth getting it checked by a professional.

Boiler pressure keeps dropping?

If your boiler pressure keeps dropping, give your engineer a call to avoid any further damage to your heating system, or worse, your lovely home. Causes for consistent drops in boiler pressure could be a faulty valve on your boiler or a leak. Either of these can be fixed, but will require a professional to make sure the job is done properly and won’t creep up again.

Unfortunately, leaks can be hard to find as pipework tends to be hidden in the walls, for appearance’s sake. Look out for swelling, bubbling or flaking of wallpaper or skirting boards as these are good indicators that water is escaping somewhere in your system.

If you can’t find a leak anywhere, that’s good news, but now focus on the boiler itself to pinpoint why your combi boiler is losing pressure. There may be a faulty valve that needs replacing or the issue may lie with a component inside the boiler itself. It is definitely best to allow your engineer to take closer look in this case, as a component may need replacing as soon as possible to avoid further damage.

Boiler pressure keeps rising?

Are you finding the opposite problem? Does your boiler pressure keep rising, even once you have checked your valves are tight and bled your radiators? This may also gloomily be due to a more serious fault.

Call your engineer out to take a look at your boiler pressure release valves or vents, as they could be the culprits, if they aren’t doing their job correctly. Their purpose is to release any excess pressure and prevent your boiler pressure from rising and becoming too high. If there is nowhere for the extra pressure to go, it can wreak havoc for the health of your boiler - so don’t delay getting professional help.

Think Your Combi Boiler Problems Could Be More Serious?

Sometimes, problems with a boiler’s pressure aren’t so easy to solve. In these cases, it may well be time to take the plunge and invest in a new combi boiler.

There are plenty of brands out there with high-quality components and an almost guaranteed lifespan. It’s rare you’ll find serious issues with Worcester boiler pressure and other reputable brands, so it is definitely worth an initial investment to make sure your boiler lasts many years. Here at BOXT, we provide a quick and easy-to-use platform for you to compare boiler prices and find one that is perfect for your home.

< Back to guides