Boiler technology has improved dramatically over the last couple of decades, and thankfully, boilers are much more reliable than in the 80’s or 90’s.

However, for three seasons of the year, a boiler is working hard on a daily basis, which will inevitably lead to some kind of issue or fault developing over time.

Water Leak Detection Team

A problem which can appear quite frequently, is a boiler losing pressure. The good news in regards to this issue is that in the vast majority of cases, you will not require the services of a qualified central heating engineer.

This article aims to provide you with clear and easy instructions on how to identify the problem and hopefully solve it yourself. 

Is There A Simple Way To Identify That My Boiler Pressure Is Too Low? 

The vast majority of UK households have a gas combi boiler for both their heating and hot water requirements. Virtually all of these types of boilers have a pressure gauge installed generally on the boiler’s front panel. Most of these gauges have a similar style of design and contain red and green zones.

In layman’s terms, the ideal situation would be where your boiler gauge needle is sitting within the green zone, which is usually anywhere between 1-1.5 bars. Although not perfect, if the needle has gone above the green zone into the red zone, there is no need to panic, as this indicates the maximum safe operating pressure.

Alternatively, if the needle has dropped below the green area, then this is an indication that the gas boiler pressure is now too low, and you should take immediate action to rectify the situation.

Another key sign, which might actually cause you to go and check the boiler pressure, is when your radiators are not heating up as efficiently as they normally do. In most cases, a quick check with the boiler gauge will confirm that your boiler pressure has dropped.

Can Low Boiler Pressure Cause Any Significant Damage To My System?

The good news is that there is minimal risk of low pressure causing any long-term problems, or indeed any significant damage to your boiler or central heating system. The more significant issue with low pressure is that it can dramatically affect your heating system’s efficiency and effectiveness. This means that your boiler may struggle to keep the house nice and warm, and your energy bills could rise exponentially as your boiler works hard to try and increase the temperature. That is why this is not a problem to be ignored and one that should be dealt with as a matter of urgency. 

We also have an article on How To Drain & Refill Your Combi Boiler

What Is The Primary Cause of Low Pressure in a Boiler?

There are several reasons why your boiler pressure may be dropping, but the most common cause is either a leak in the system, however small or a result of the homeowner bleeding the radiators, which in essence removes air from the system causing pressure to drop. 

How Can I Find A Water Leak?

This might sound like a rather silly question to ask, but not all leaks are visible to the eye, at least initially. The leak could be behind the skirting board, or under floorboards, in an area that is not visible.

The first thing to do is to walk around your home and visually check all of the exposed pipework and radiators for any sign of a leak. You are looking for water on the pipes themselves or moisture on walls, flooring or woodwork. If a minimal amount of water is leaking, you might also discover a green build upon any copper pipes. As you might expect, the most significant risk is at the joints or where the pipework is connected to the radiator.

One common mistake people make in a predominantly cold room, where there might be some condensation, is to confuse condensation for a leak, so be aware of that. If you cannot find the leak yourself, you could contact a leak detection specialist, who can typically locate the leak for you. 

Have You Recently Bled Some Radiators?

The most straightforward solution to low boiler he most straightforward solution to low boiler pressure is to repressurise the system. This is normally a very simple procedure that can be done without the need for professional assistance.

Consult your boiler user manual to confirm that your boiler is suitable for home repressurising.

Provided that your boiler can be repressuried without the need for a professional, follow these simple steps to complete the process.

Step 1

Look closely at your boiler, and identify the location of the filling loop and your pressure gauge. When it is turned off, the filling loop handle or knob should be t a 90-degree angle to the pipe’s flow.

Radiator Leak Causing Boiler Pressure Loss - Being Repaired

Step 2

At all times when completing this process, it is imperative that you can see the pressure gauge, as it will guide what you need to do.

Step 3

Turn off your boiler for safety purposes before you begin any adjustments. 

Step 4

Turn the filling loop handles 90 degrees so that they now match the direction of the pipe. You will know that you have done this correctly when you hear water flowing.

Step 5

Keep the loop handles turned until the gauge shows the desired pressure. Upon hitting this pressure, turn the handles back to their original position, ensuring that they are properly turned off.

Step 6

Turn the boiler back on, turn the heating system or hot water on, and confirm via the gauge that the pressure is being maintained within the green zone.

If the pressure is maintained, then you have resolved the problem and have nothing else to worry about. If the pressure begins to drop again, this is a clear indication of a more significant issue, which will require a Gas safe, qualified engineer.