Boiler pressure issues

[Meljc]

Evening all
We have a pressure issue with our boiler and wondered if anyone can help give me an idea of what the issue could be.

whenever the heating is off the pressure drops to 0.4 on the boiler control and 0 on the top up dial in the airing cupboard.

Each morning I have to top the pressure up to 1.0 for the heating to kick in.

Then after about 10mins the boiler pressure is too high, usually 2.6 - 2.8 according to the boiler and I have to keep bleeding the nearest rad to bring the pressure down to stop the boiler from stop/starting.

if the heating is running it seems to hold the pressure. But a short while after the heating clicks off the pressure drops again and I have to top it up to get the heating back on next time.

When I top up the pressure it makes a noise like it’s not just water going in.

Can anyone give me any ideas? Our plumber seems to have given up with our boiler and is not responding to messages, think I need to find a new one!

many thanks

 

[CBW]

I think you have an expansion issue, or a blocked pressure sensor. What boiler is it and how old?

 

[Meljc]

It’s a Murelle HE EV and is about 5 years old.

 

[sxturbo]

Sounds like the expansion vessel requires re-pressurising or replacement.

Need someone qualified to fix it

 

[Mottie]

Sounds like the expansion vessel requires re-pressurising or replacement.

Need someone qualified to fix it

I thought that was only for unvented domestic hot water? Does it apply to sealed heating systems as well?

 

[Harry Bloomfield]

1. Expansion vessel failed, or its air pressure needs topping up
2. The pressure release valve is passing.
3. You have a leak on the system somewhere

 

[CBW]

It’s a Murelle HE EV and is about 5 years old.

Looking at this, it doesn’t need to be a gas safe registered engineer, as the cover doesn’t seem to form part of the combustion circuit, although I could be wrong. Sounds likely that the expansion vessel has lost its charge, or has failed/ruptured. It’ll need sorting ASAP, before you cause any more issues with your heating system.

 

[Mottie]

Ah, so heating expansion vessels contained within a boiler casing may need a gas safe engineer as opposed to a registered G3 engineer?

 

[CBW]

Yes G3 relates to an unvented cylinder, boilers relate to gas engineers.