Which valve to increase boiler pressure?

The first thing to do if you suspect that your boiler is suffering from low pressure is to look at the water pressure gauge on the front of the boiler. Different boilers have different pressure gauges, so it is essential to look for the right information. This can be found in the user instructions for the boiler.

If you have a digital gauge, then your boiler pressure is typically represented by bars. If the reading on the screen is less than 1 bar, then that is a sign that there is low pressure. Your display may also indicate low pressure by delivering a pressure warning or a flashing reading.

If you have a hydraulic gauge, then your boiler reading is likely to be on a dial. There will be red sections on the dial which indicate low and high pressure. If the indicator needle is in the red part on the left-hand side, then the pressure is too low. If it is in the red section on the right-hand side, then the water pressure is too high.

Tip: Check the water pressure on a regular basis to avoid waking up without any heating or hot water!

Ideally, you want to see a reading of between one and two bars. When your radiators are cold, it’s normal to see a water pressure of one bar. Anything below one bar is considered low pressure, whilst 2.75 bars and above is considered high pressure.

Remember, if you are experiencing high pressure, it is best to call out an engineer to fix the issue as soon as possible. There are few scenarios which may lead to a boiler’s pressure being higher than it should be; the heating system may have been overfilled with water, or pressure release devices in the boiler could be failing.

Reducing high pressure on your boiler can be dangerous, so it is always best to let a qualified heating engineer complete this for you.

Usually, low boiler pressure comes from two main issues:

One issue can occur after bleeding radiators. Releasing water from your central heating system can lead to a pressure loss. Fortunately, there is a way you can increase pressure in your boiler system, without having to call out an engineer.

The other reason for low boiler pressure is that there may be a leak somewhere in your central heating system. This leak may be small and barely perceptible, which is why the drop in pressure has been gradual.

You can see if this is the case by looking for damp patches near the radiators, pipes and boiler. Remember, not to look for leaks inside the boiler unit itself; this is best left to a Gas Safe registered heating engineer.

If you find the leak, then an engineer should be able to fix the problem for you. If you cannot find a leak and low boiler pressure persists, then calling out an engineer to help find the problem can save you time, stress, and cost in the long run.

Firstly, it’s essential to check your boiler manual before you begin to re-pressurise the boiler. Every boiler is different, so go for the manufacturer’s instructions first. Many manufacturers also post instructional videos on their website for how to repressurise your boiler, so check them too for a step-by-step visual guide.

Remember, that if at any point you are concerned about your boiler system, then it is best to call out a Gas Safe registered engineer than try to fix the issue yourself.

You should only repressurise your boiler when you discover that it’s too low, though we do recommend checking the pressure every few weeks, just to be on the safe side.

If you have to repressurise the system on a regular basis, this indicates that there’s a leak somewhere in the system. To prevent water damage, it’s best to find this leak and fix the issue.

A quick look at the pressure gauge is enough to check your boiler’s pressure. Depending on what model your boiler is, this comes in different forms:

The process is simple:

Your boiler deals with this itself.It is equipped with a safety valve which releases the excess pressure.That means it’s perfectly normal to see a drop of water on this valve from time to time.

However, if you spot a continuous flow of water, call your heating engineer.Either your valve is defective or your system is overpressurised.

If the pressure increases continuously despite the water discharge through the valve, check that both filling valves are closed.What if the pressure doesn't decrease?Turn off the boiler and call your installer.

It is sometimes a good idea to check whether the radiators need to be bled. This operation removes air and some water from the circuit, which will lower the pressure. But if it stays high after bleeding, turn off the boiler and call your installer.

Be careful because if the pressure exceeds 3 bars, the safety valve will remain open and you risk a small flood.If this happens, turn off the water supply to the boiler by closing the isolation valve. If you can't find it, turn off the water supply at the meter and wait for the heating engineer to arrive.

There is no need to check it every day, or even every week. The pressure generally remains stable. The expansion tank compensates for variations in volume (and therefore pressure) caused by expansion and contraction related to temperature variations.

26-05-2018

A loss of water pressure is a common reason your boiler might stop working.

Increasing the water pressure in your gas boiler is a task that can be completed without needing to call out a Gas Safe registered heating engineer. However, if you're unsure about anything, have questions or encounter any difficulties whilst increasing your boiler pressure, contact our friendly team on 01295 224844 today, or email hello@mnheating.co.uk and we'd be more than happy to assist you.

Before you attempt to increase the water pressure in your boiler, ensure your central heating system is cold, your boiler is switched off and hasn't been in operation for at least one hour.

To discover whether you have low water pressure, you need to check the pressure gauge that is often located on the front of your boiler. If the water pressure is below 1 bar when not in operation then your boiler will struggle to operate safely and efficiently. Your boiler requires a consistent water pressure between 1 and 2 bar.

To increase the water pressure in your boiler, you'll need to locate the filling loop often on the underside of most gas boilers. The filling loop should have two valves at either end with tap handles (or flat-head screws on older boilers). You need to open both the valves to allow cold water into your heating system, you should be able to hear this flow of water. Keep an eye on the pressure gauge and close the valves when the pressure reaches 1.5 bar. Once both valves are securely closed, switch your boiler back on and reset the fault code (if necessary).

Whilst increasing your boiler pressure doesn't require you to be Gas Safe registered, never attempt to fix your boiler yourself. It is illegal to work on gas appliances if you aren't Gas Safe registered.

If you're unsure about these instructions or think a low water pressure may not be the cause of your boiler not working, please don't hesitate to contact our friendly team today on 01295 224844.