If your boiler keeps losing pressure, you’re not alone. This is very well known and is a common boiler repair job that requires a quick call to your plumber. There are many reasons why this can happen.

What Is A Boiler Water Pressure?

Boilers are the worst espeically when they have loads of problems in the colder months, espiecally when you don’t have any hot water. When this happens it indicates that your pressure is too high or maybe even too low.

Your boiler heats cold water that flows around a circuit of pipes and radiators throughout your home. For it to be effective you’ll have to make sure your pressure is stable.

How To Check My Boiler Pressure?

One of the most common question is how to check my boiler pressure. So for a common modern boiler such as a combi boiler the pressure gauge is around the frnt of your boiler or underneath the control panel.

However if you have an older boiler then your pressure gauge is underneath the pipework, if your struggling to find it then look in the instruction manual.

What Should My Boiler Pressure Be?

A normal boiler pressure should be around 1-2 bars. The ideal boiler pressure is often marked as a range within the green area on the gauge itself, whereas red will indicate the low and the high boiler pressure zone. Bear in mind that your boiler will still continue to work, if the pressure is in the red zone.But if your shutting down or won’t snitch on here at Origin we have got you. Even if your boilers working well, it’s a good idea to check your pressure occasionally.

Why Does My Worcester Boiler Keep Losing Pressure?

Your probably wondering why your boiler keeps on losing pressure? Right well here at Origin we will provide you with all of your answers to your questions. One of the worst issues is that your boiler is less than 1 bar on the pressure gauge. Which isn’t an error code but it is a problem which is indiciating that your boiler has low pressure.

There can be many reasons for why your worcester boiler is losing pressure, but bare in mind that it is normal for a boiler to slowly lose its pressure overtime but it can also be caused if you’ve recently bled your radiators. Although if you have noticed a huge drop in your pressure then it might mean you have a leak in your system.

Here is a few reasons for why your boiler may lose pressure:

What Causes A Boiler To Lose Pressure?

  • A leak in the central heating system
  • The expansion vessel has lost its air
  • Pressure relief valve passing water

How To Fix A Leak Within The Heating System

To find a leak within your central heating system, the first step to do is to check all of the radiator valves. The most commonly known place to find a leak is on the radiator valve, an easy way to check is any signs of water or old water damage like stains and rust.

Sometimes you can also fix a radiator leak, which is fixed by tightening one or some of the nuts on the valve. There are 3 places on a radiator valve that can leak from tightening the nut with an adjustable spanner. After fixing the leak, you should be able to bleed your radiators and repressurise the boiler to 1 on the pressure gauge.

If the leak is not on a radiator, you should check your boiler and any of your central heating pipes on show within your house. However if you can’t find the leak anywhere on your heatingsystem, it could be a problem underneath the flooring.

Expansion Vessle

Another reason for why your boiler keeps losing pressure may be due to your expansion vessel. Your pressurised central heating system (combi/system boilers) they all need an expasion vessel. This is when the expansion of water from the heat when the heating system is turned on.

If your system or combi boilers keep losing pressure with no leaks then you may have a faulty expansion vessel which is causing this issue. In order to find these they may be inside your boiler or heating pipes depending on what type of system you have.

The expansion vessel is full of air, so when the heat is on it also takes some of the pressure increase away from the pipes. To fix this solution you’ll need to either recharge your expansion vessel by pumping it up with a pump. Another solution may be that the diaphragm inside the vessel is split and you’ll have to call the plumber to replace the expansion vessel.

Pressure Relief Valve

Another alternative reason for why your boiler is losing pressure could also be due to the pressure relief valve. Ll of the combi boilers and heating systems all must have a safety deviece called a pressure relief valve. This is a device that will protect your centrl heating system from building up with too much pressure and causing radidaitors and boilers to blow up.

In order to fix this solution so your boiler doesn’t lose pressure, you should keep checking your blow-off pipe outside for any dripping water. If it’s dripping therefore you’ll need to replace the pressure relief valve.


This question is asked a lot and the answer is yes, a boiler can defineinlty lose pressure without a leak. A leak is the most common cause of a boiler losing it’s pressure, however it could alos be due to an expansion vessel problem or a pressure relief valve, or by bleeding radiators.

A boiler should never lose pressure unless their is a huge issue. If your central heating is losing pressure slowly, then you might notice a small leka within your central heating system.

Your boiler pressure should be around 1 bar, when your heating is off and the system is cold. However if you notice that it has dropped below 1 bar, then you will need to repressurise your boiler as soon as possible. When your heating is on, it’s normal for the pressure gauge to be around 2 bars.