Why does my boiler keep building up pressure?

All closed systems (i.e. a combi boiler) have an expansion vessel to allow for excess water levels. Unfortunately, these pipes can become clogged by dirt and debris, which results in a pressure build up within the system. To check this, turn off your heating system and look to see if there is a build up in the pipe.

What happens if boiler pressure is too high?

What happens when the boiler pressure is too high is that the system comes under unnecessary strain. This often means that the parts in the boiler become worn down by the high boiler pressure and seals and pipes crack, allowing water to leak out of the bottom.

Does the pressure go up on a boiler when its on?

When you turn the heating on the water in the pipes and radiators heats up and expands. This water expansion causes the pressure to increase in the whole system. So, when the heating is on you should notice the boiler pressure on the gauge to increase slightly but not above 2 bar.

Is it normal for boiler to lose pressure?

A boiler that keeps losing pressure is therefore always cause for concern. There are two main problems that typically cause a loss of pressure – water escaping somewhere in the system or a failure of the expansion valve and resulting damage to the pressure relief valve.

How often should you Repressurise boiler?

Read our guide on how to repressurise your system. If pressure rises by more than 1 bar when the heating is up to temperature then the expansion vessel may require repressurising. This will require a service engineer. The pressure in the system will usually require topping up once or twice a year.

When do you know if your boiler needs to be replaced?

On most digital gauges, you’ll see a flashing pressure reading, if there’s a low (or high) pressure warning. If your boiler pressure reads less than 1 bar, it’s possible that you might have lost water from the system, which needs to be replaced. This is where that filling loop (or filling link) comes in again!

What does it mean when boiler pressure keeps rising?

The boiler pressure should change depending on if the heating is switched on – in fact, a small rise in pressure between when a boiler is switched off and when it is heating up is a sign that the boiler is working perfectly. However, a warning sign to look out for is if the combi boiler pressure keeps rising above the levels stated.

How can I lower the pressure in my boiler?

To eliminate air pockets, you need to bleed your heating system. This will help to stabilize pressure. Obtain a small key from a hardware shop. Explain that you need to bleed your boiler. Fit the key into the slot at the radiator. Slowly turn it to release pressure until you attain the desired level.

Is it normal for boiler pressure to be over 1.5?

A combi boiler pressure gauge reading over the 1.5 mark whilst the heating is in full operation, is likely normal due to the water demand being placed on the boiler so it’s likely nothing to worry about. In this instance, a reading between 1.5 – 2.5 bar can be considered normal.

What should the pressure be on my boiler?

When your boiler is switched off, the pressure gauge should read around 1 Bar – in the green zone on the gauge. When it is in operation (demanding heat/hot water), it’s pressure will increase slightly, then it should drop back down. Need help?

What happens if the pressure on a combi boiler keeps rising?

High combi boiler pressure that keeps rising is not inherently dangerous, but can lead to expensive damage down the line. If pressure gets too high, more often than not, your heating system will simply cut out due to the PRV (pressure release valve) in place.

Where is the expansion vessel in a boiler?

Expansion Vessel. This is found at the rear of the heating system. It regulates pressure rises in the system. It sometimes becomes necessary to re-pressurize this vessel to prevent frequent rising pressure in the set-up.