There are a few occasions where your boiler is going to let you down. One of them is looking forward to a nice hot bath or shower, only to turn the tap on to find there is no warm water.
Most people will wait a few seconds just to see if the water heats up and when it doesn’t, it is most likely your boiler losing pressure. One of the great things is it is very easy to find out why your boiler is not performing as expected.
It is usually straightforward to resolve a boiler losing pressure yourself. But first, you are going to have to investigate the situation.
It is quite possible that your combi boiler can lose pressure for the following reasons-
You have an issue with an expansion vessel.
A leak has appeared in the heating pipework.
You have recently bled your radiators.
Or there is a leak in the pressure relief valve.
You can find out some more information about why your boiler might be losing pressure below. As well as some steps to re-pressurising your boiler.
What is boiler pressure, and how does it work?
Before you get to fix the problem, it helps to understand how the appliance works. And that means you should understand exactly what boiler pressure is.
We all know that our boiler heats cold water and then can distribute it in a circuit of pipes and radiators around at home. For the boiler to be able to distribute this one water, it needs to ensure it has proper pressure.
It is this pressure that pushes the water through the pipes. In combi boilers, the pressure is often controlled by a filling loop that is connected to the cold water supply. And that is it.
What is normal boiler pressure? And how can I check it?
As a general rule, most boilers will have pressure between 1.0 and 1.5 farce. If you are wondering how you can check the boiler pressure, this is a very simple and fast process. The first thing you will need to do is to locate the pressure gauge on your boiler.
This is usually located on the front part of the appliance.
The pressure gauge will have two coloured sections, one green and one red. If the pressure is too low or beneath 1.0 bar, the needle of the gauge will be below the green section. If the pressure is too high, this is 2.5 bars and over, the needle will be In the red section.
Pressure loss due to water leakage
One of the hardest problems to identify is a pressure loss due to water leakage. As you know, most pipework is hidden within the walls of your home or behind cupboards and panels. Which means it can be quite challenging to conduct a visual examination.
If the leagues are hard to pinpoint, it’s very important that you still find them.
Leaking can cause damage over time to all of the surrounding materials. Hidden leaks can result in unsightly and dangerous mould rot and a lot of other expensive damage.
One of the first places that you will look when looking for pressure loss due to water leakage is the joints and fixtures. These will usually be in easy to access and invisible locations.
Water leakage tends to occur where the supply pipes are connected to radiators.
The risk of leak leaking is increased if the fittings allowed any movement of the radiator.
How to detect leaks?
If you suspect that there might be a leak in your system, the first point of call is to examine all the connections to your radiators. Even if that pipework is wet to touch, this doesn’t signify that there is actually a leak in that area.
This can often be caused by condensation, which is due to the temperature differences on the inside and the outside of the pipe.
This can make it more difficult for you to diagnose a problem. If you do have suspicions that one of the joints is leaking take a paper towel and dry it off. Then place a tray or a piece of paper underneath it.
Check back regularly to see if the paper becomes wet or if there is a regular drip.
Another indicator that there is a leak that is impacting a particular joint, you might notice bubbling paint flaking that can appear on the pipe all the skirting board. You may also notice a swelling up, rust marks, listing of the skirting board, and sometimes water stains on the ceiling below the area.
When you do find a leaking joint, it is vital that you get it repaired and replaced by a professional.
If your boiler does maintain pressure after this, then it was likely that that leak was indeed the problem. If your boiler continues losing pressure, and there is no leak, there is potentially a fault with the boiler.
How to repressurise your boiler
You will need to Identify the filling-loop as well as the pressure gauge. The filling loop handles should be at a 90° angle to the flow of the pipe.
Check that you can see the pressure gauge at the same time as accessing the filling loop. Many sealed systems will operate at around 1.0 – 1.5 bar you should consult the manual for your specific boiler brand. Correct pressure level will often be shown on the gauge for modern systems.
Turn the boiler off.
Turn both filling loop handles to match the direction of the pipe – you should begin to hear water flowing.
Be careful as it is possible to over-pressurise the boiler. Check the gauge at all times. You may need somebody to assist you if this is not possible. Once correct pressure is reached, close the handles fully.
Turn the boiler back on and observe.
What causes a boiler to lose pressure
1. Boiler leaks – Boiler leak is one of the most common reasons for a boiler to lose pressure. This is, of course, an actual leak on the appliance. Boilers do have several weak parts, including the washers, the ring joints, the automatic air vents and more. Boiler leak is not a small issue, and it is important that you call a professional heating engineer out to inspect and repair the unit.
2. Faulty pressure on relief valve – The pressure relief valves are designed to let out any excess pressure, and this usually happens when the boiler exceeds three bars. When a valve, whether external or internal becomes faulty, it will start to leak water from the central heating system. In this situation, it is very important, and you call a professional to change the valve for you.
3. Damaged expansion vessel – you can very quickly notice if you have a damaged expansion vessel because your boiler pressure will rise to 3 bars as soon as it heats up. The reason this happens is the expanded water in the system has nowhere else to go. And what happens next is at the pressure Relief valve will let out the excess pressure from the boiler.
However, re-pressurise of your expansion vessel is typically part of your annual boiler service. This procedure will prevent these issues, such as a damaged parcel from occurring in the first place. However, a dent repair the damage expansion vessel is quick and easy to repair; this really should be done by a licensed professional.
4. Radiators recently bled – If you have bleed your radiators recently, then you may notice that the boiler pressure has dropped. Great news here is that fixing this issue is very easy. In order to fix a low boiler pressure because you have recently bleed your radiators, you simply have to re-pressurise the appliance. In order to do that, follow the steps above in the ‘how to repressurise your boiler’ section.
5. Broken parts – if you have a look for leaks on your pipes, you haven’t recently bleed your radiators, and nothing else seems to match up the chances are you have a broken part. Your boilers monitor will most likely show the appliance needs to be checked up. If there is anything broken it will need to be replaced, and the best thing to do here is to call the professional to give your system a once over. If the unit is on the older side, it can be better to replace your boiler entirely. As older parts can be very expensive, and sometimes the cost of repair is more expensive than replacing the boiler with a new one.
If you do suspect that your boiler is losing pressure and you can’t put your finger on why it is always best to get a professional out to check out your boiler. Most of the time, a professional will be able to find the problem and fix it in no time.
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