Vokera Option Combi over pressure

[AnonymousImport]

Hi,
Can anyone help?
Have a Vokera Option Combi Boiler. When we run the central heating the pressure goes up to over 3 bar and water starts pouring out of the overflow.
Tried releasing the pressure by pulling up the pressure release tap. This drains water out of the system, but then the pressure builds back up again.
Nothing has been done to it recently. Started about 2 weeks ago and got progressively worse. Only starts when we run the central heating.
Also can we damage the system further if we continue to run it?
Any ideas?

Thanks all.

 

[kirkel]

the system over pressure can be caused by several things, make sure the filling loop is disconnected and not passing water which will over pressurise, more likely your problem is caused by either a faulty pressure relief valve or a faulty expansion vessel, to test the expansion vessel you need to press the shreider valve ( similar to a car tyre valve)briefly, if the vessel is faulty you will get some water from the valve and means the vessel will need to be renewed.
The diaphram being torn allows water to mix with the air and leaking via the blow off pipe

 

[pukkalad]

Thanks Kirkel,

checked the valve, no water.

What else could it be?

thnx.

 

[AlanE]

Expansion vessel needs repressurising.

Alan

 

[oilman]

Search the forum, there are lots of posts on checking expansion vessels.