Volatility in combi CH system pressure

[Confused...]

I bled a radiator that was full of air and repressurised the combi CH system

When the CH next came on, the boiler showed that the pressure had risen from 1 bar to in excess of 3 bar. Prior to this the pressure had been reasonably stable at 1.0 to 1.5 bar when the boiler was running at full speed

Since then, the pressure when cold/idle has dropped to 0.3 bar

Any ideas? Its a 10 year old Vaillant combi.

The system consists of 9 radiators and two UFH systems, one in the living area and one in the kitchem

Any ideas / suggestions why the pressure changes so much? And what should I do?

Thanks in advance

 

[TBServices]

The expansion vessel is gone/lost its charge.

The reason this wasn't evident before, is because the air in your radiator was acting as an expansion vessel.

You need a competent plumber to correctly size and fit a new expansion vessel.

 

[Iplumb123]

Yeah I agree, it can be a real hassle getting an internal expansion vessle replaced the fastest option is to fit an external one which shouldn't take long at all to do.

 

[Confused...]

The expansion vessel is gone/lost its charge.

The reason this wasn't evident before, is because the air in your radiator was acting as an expansion vessel.

You need a competent plumber to correctly size and fit a new expansion vessel.

Thanks TBServices. The UFH systems were also fitted after the boiler. Is there potentially an issue that the expansion vessel in the boiler is now insufficient to cope with the UFH - both systems are relatively large? Is it possible to get a plumber to fit a larger or secondary expansion vessel?

Thanks again

 

[TBServices]

Thanks TBServices. The UFH systems were also fitted after the boiler. Is there potentially an issue that the expansion vessel in the boiler is now insufficient to cope with the UFH - both systems are relatively large? Is it possible to get a plumber to fit a larger or secondary expansion vessel?

Thanks again

Yes it's entirely possible that the vessel in the boiler is now undersized. Hence why I previously mentioned that any new vessel needs to be sized accordingly.

If you have space, an external expansion vessel will be the best option. Even if the internal is big enough, chances are after 10 years its bust anyway.

You can post in the looking for a plumber section of the forum for help getting someone if you need.

 

[Confused...]

Thanks again

Given the age of the boiler (13 years) might I be better off just replacing the boiler with something more appropriate to the system even if the cost is significantly more

Regards

 

[Dotty]

Certainly worth considering, again, post a request here - [DLMURL="http://www.ukplumbersforums.co.uk/im-looking-plumber-gas-engineer/"]I'm looking for a Plumber or Gas Engineer[/DLMURL]

And remember to include your location.