August 31, 2021

Boiler Pressure: Everything You Need To Know

Especially in the winter, no one wants to be without heat or hot water in their home. One of the most frequent causes of boiler issues is too high or too low boiler pressure. In this tutorial, we’ll cover all you need to know about boiler pressure, from how to check your boiler pressure to how to repressurize your system.

No matter what your requirements are, we offer a broad variety of boilers to pick from if you’re seeking to replace your boiler due to pressure issues.


For what reason is boiler water pressure so essential in the first place?

As a result of your boiler’s ability to heat water, the pressure of the boiler’s water is crucial. For combination boilers, a ‘filling loop’ that links to your water line will keep the pressure up. As the pipes expand and contract with the heat, your boiler’s water pressure must remain constant to guarantee that no issues occur while your house is being heated.


When it comes to a boiler, what is the ideal pressure?

Depending on the condition of your system, it should have a pressure of between 1 and 2 bars. The term “low pressure” refers to when the gauge is below one bar, whereas “high pressure” refers to a gauge over 2.75 bars While it is essential to read your boiler’s handbook for the precise water pressure your boiler should have, it may vary across brands and types of boilers.


If you’re using a boiler, what pressure should it be at?

Boiler pressure should be between 1.5 and 2 bars while your heating is on. Pressure zones on most boilers are color-coded to assist you check whether your boiler is properly pressurised. An indicator for boiler pressure is usually in the green zone when it’s at the proper pressure, but if it’s too high or too low, it’ll be in the crucial red zone.


The pressure in the boiler should go up when the heating is on, or not?

There should be a little uptick in your boiler pressure when the heating is on since the heated water expands and causes the pressure to raise throughout the whole system. Consequently, when the heating is on, you should observe a small rise in boiler pressure, but not over 2 bars.

When you switch on the heating, check your boiler’s handbook for the optimum operating pressure to ensure it doesn’t rise by more than 1 bar.


Your boiler’s pressure should be at a certain level when the heat is turned off.

There is a typical water pressure of 1 to 1.5 bar in your radiators when the central heating system is switched off and the radiators are cold. In other words, the pressure gauge needle should always be in green. Most manufacturers suggest a boiler’s optimum working pressure to be 1.3 bar, but always check your boiler’s handbook to be sure it’s operating at the appropriate pressure level.


How to check the pressure in a boiler

Most modern combi and system boilers come with built-in pressure gauges, so you can quickly monitor the boiler’s pressure. Depending on whether you have an old-fashioned hydraulic gauge or a contemporary boiler, your gauge may show pressure using a dial. Hydraulic gauges include green and red zones, as described above. Digital gauges have flashing warning lights when the pressure is too low or excessive.


Is there a problem if your boiler pressure is too high?

Having a high boiler pressure does not always imply that it is hazardous. It’s the expansion vessel that regulates the balance of air and water in your boiler. If your expansion vessel has too little air, the pressure may grow too high, causing water to leak out of the pressure release valve. Boilers often shut themselves off when the boiler pressure becomes too high. Consult a competent heating engineer if this occurs.


How to lower the boiler’s operating pressure

Your boiler pressure may be excessive if you have recently topped it up too much or have not properly shut down the release valve. As a general rule, the valves are located beneath your boiler and must be firmly closed. Valves that have not been used in a while may have fallen loose or been inadvertently knocked, creating pressure issues.

The radiators may be bled if you’re still experiencing trouble with your boiler pressure. You may wish to contact a boiler service technician, even though this is a simple job, since the water may be boiling and possibly hazardous, particularly if there are children or pets present.


What to do if your boiler pressure has decreased due to a variety of reasons

Boiler pressure may be too low for two reasons. Small drops may not be an issue if you check your boiler frequently, but abrupt drops that leave you without hot water or warmth may be the result of the following.


Leakage of Water

As a result, your system’s pressure will be reduced. While it’s possible that the leak is tiny and undetectable, the pressure will steadily decrease over time and cause all sorts of heating and hot water issues. A water leak may be detected by looking for wet or damp patches near pipes, radiators, and even the boiler.

Try to avoid looking inside your boiler – a Gas Registered engineer will need to perform this. You should also consult with a Gas Registered Engineer if you discover a leak or need to fill up the water pressure frequently.


A Radiator Must Be Bled

You may have lost pressure in the boiler system if you recently bled your radiator. There’s a pressure drop in your system as a result of the air being let out of your radiators.


When it comes to boiler pressure, is it hazardous to have it too low?

This implies that you can’t circulate or supply water to taps and showers. To warn you of a low pressure problem, the system will typically shut down and show an error code.

Low boiler pressure is usually nothing to worry about, but if you have any worries, you should always see a Gas Safe Engineer.


Low-pressure boiler repressurization: how to do it

To repressurize your system, consult the handbook that came with it, since each boiler pressure system is different. Check your boiler manufacturer’s website to see if they have any useful instructions and videos on how to top up the system’s water supply.

Adding additional water to the filling loop will enable more water from the mains supply to go into the system. They come in two varieties: built-in and external.

Depending on the design and filling procedure, filling loops may vary, but here’s the fundamental approach:

1. Turn off your boiler and allow it to cool for a few minutes before using it again.

2. Your boiler has a filling loop.

3. When utilising the filling loop, make sure you can see the gauge.

4. Allow water to enter your system by opening both valves.

5. You’ll need to wait until you see the pressure indicator rise to 1.5 bars before closing each valve.

6. Restart your boiler and click the reset button if necessary.

7. Be sure to delete the filling loop if it’s a part of your installation. Be on the lookout for any remaining water.

Call a Gas Safe certified engineer to assist you whenever you are in doubt or don’t feel confident about repressurising your boiler yourself.


How to relieve boiler pressure

A Gas Safe certified engineer can help you relieve pressure if you’re experiencing excessive boiler pressure.

1. Turn off your boiler and allow it to cool for a few minutes before using it again.

2. Check the gauge’s reading.

3.If the gauge reads more than 2 bars, the pressure will need to be lowered to keep the vehicle safe.

4. The filling loop or relief valve should be firmly shut.

5. Radiators should be bled.

6. The pressure should have restored to its original setting.

A Gas Safe certified expert should be contacted if your boiler’s pressure continues to rise.


Further assistance and guidance

You may use our resources to get more information about other boiler related concerns below: