my valliant boiler is loosing pressure have to top up every 10 days or so. plumber said its the expansion tank and he could not get another and will put a external tank out side the boiler. Is this the best option does any one now.

Ems, May 2009

Constantly losing pressure means a water leak somewhere...either within the boiler itself, the system pipework and radiators, or to the outside via a leaking pressure release valve. The expansion vessel, if faulty, will eventually fill up with water anyway - maybe its leaking itself? They are really there to keep the water pressure constant and they can be fitted externally from the boiler.

John, May 2009