How to Reduce Boiler System Pressure


Is your boiler pressure too high?

Fluctuating boiler pressure is a common problem, and one most of us will encounter at some point.

Boiler pressure refers to the strength of water pressure running within the sealed central heating system.

When heating or hot water is turned on, the pressure will increase as it heats up – dropping off again once it’s turned off – this is completely normal.

A boiler consistently operating at high pressure will struggle at high capacity over time, and could eventually fail – even causing damage to your home.

If you’ve noticed the pressure in your boiler is higher than usual, our helpful guide can tell you why this happens, and show you how to make simple checks to diagnose a problem, and help you fix it.

What Pressure Should My Boiler Be?

Start by working out the correct pressure for your boiler.

Not every boiler has the same pressure requirements. You can easily find out the optimum pressure for yours by checking the manual.

This will contain accurate measurement information, so you’ll be able to determine what the pressure should be for your particular model.

If the reading you see on the pressure gauge is too high, it might be due to some of these common causes. 

What Causes High Boiler Pressure

The pressure of your boiler can vary – rising up as well as dropping down due to expansion and contraction.

To better understand this, it’s important to know the typical reasons why the pressure in your boiler can rise.

So how and why does high pressure occur?

Excess Water in the Boiler’s Central Heating System 

One of the most common and frequent explanations for high pressure is the overfilling of water in the central heating system.

Excessive water in the boiler’s system can lead to it being over-pressurised. Ideally, a boiler needs just the right amount of water in its system to run efficiently – not too much or too little.

Overfilling often occurs after the pressure is adjusted from being too low. If the valve or filling loop has been left open it can draw in too much water.

Check that the filling loop valve is closed tightly or completely removed.

Expansion of Boiler Parts

This particular problem happens naturally over time.

As your boilers water content heats up, the pressure in the boiler increases. Heat causes the act of expansion – so parts will moderately swell accordingly.

Faulty Parts

This can include anything from a faulty pressure release valve or filling loop to the expansion vessel – responsible for maintaining consistent boiler pressure.

Old age and natural corrosion can also play a role in your boiler’s ability to run reliably and efficiently.

Leaking Pressure Relief Valve

Leaking pressure relief valves are commonplace.

Too much or too little air in the expansion vessel can result in the heating system becoming over-pressurised. If you find water on or around the pressure release valve or pipes (external of property), it could mean the system is compromised.

A faulty part is not something you can fix yourself. If you’re unsure of what to do, contact a boiler specialist from Blue Emergency Cover, who can diagnose the problem.

How Can I Check My Boiler Pressure?

Here are some of the quick and easy ways you can determine whether your boiler’s pressure is correct, or running too high.

Most boilers have different gauges located on the front of the boiler that tell you the exact pressure.

Yours will likely either have a digital display that uses number bars (and a green to red display), or a round hydraulic gauge with a needle on a dial that points to the pressure level.

If you have an older boiler, your pressure gauge could be underneath the boiler instead of on the front panel.

The pressure is too high if:

  • The dial reads above two (two bars) or has moved from green to red.
  • The heating system has shut down.
  • A flashing error appears on the LCD display.

If unsure, check your boiler’s instruction manual for further information.

How to Reduce Boiler Pressure

In the majority of cases, anything above two bars is an indication that your boiler pressure is too high.

There are a few simple steps you can try to lower boiler pressure or release pressure from the boiler:

  1. Switch your boiler off and wait for the system to cool down.
  2. Check your boiler pressure gauge (between 1 – 2 bars).
  3. Is the filling loop tightly closed? (Turn off clockwise).
  4. Bleed the radiators to release any trapped air from the system.
  5. Recheck the pressure gauge. Has the boiler pressure returned to sit within the ideal range of 1-1.5 bars when the boiler has cooled down?

Pressure Still Needs Releasing?

If you’re struggling to normalise the pressure of your boiler it may need a technician to attend.

No matter the type of sealed boiler or system you have – whether combination, combi, or system boiler, regularly checking the pressure of your boiler will help ensure it runs adequately and best of all, cost-effectively.

Is the boiler pressure continuing to rise? If you’re unable to fix the issue, identify the cause of the problem, or if you can’t release pressure from the boiler, reach out to our professionals at Blue Emergency Cover who will help diagnose the issue efficiently.

Blue Emergency Cover are boiler experts. As specialists, we know boilers.

We’re here to help keep your home warm all year round. Should your boiler break down, we aim to get you up and running again as soon as possible.

Did you know, that we offer unlimited repairs to Blue Emergency Cover plan customers? Speak to one of our experts today.