over flow leak and constant 3+ bar pressure. Filing loop rem

[gilezzznik]

I've got a chaffoteuex celtic plus combi.
The problem is that, even when the heating isn't on, it still creeps up to 3+bar and constantly leaks through the pressure relief valve. I'm constantly draining water from the rads to get pressure down. Where is the water coming from? I've removed the filling loop, in case the problem was that. I've checked the pressure on the expansion vessel, OK at 10 bar. Running out of options, what's the problem?
Thanks..gilezzznik

 

[ChrisR]

Water is passing from the mains either through the secondary heat exchanger, or on this model, more likely through the diverter valve.
Repair of latter would be first option.
Time for a new boiler must be approaching!

Edit - new valve retail £230
http://www.partscenter.co.uk/shared/prdinfo/images/434180.gif

 

[lightning]

hope you mean expansion vessel is 1 bar not 10 bar

 

[WDIK]

hopefully your cold water fill loop is not connected?