Since putting central heating on in October I have had a problem with pressure dropping and water coming out of the boiler overflow, however I had a burst pipe outside repaired recently and afterwards the boiler made strange sounds and water pressure was strange for a day.In fact hot tap water was a bit iffy.I've been told that it's the expansion tank and 'cos it's a vokera the heat exchanger will be next and it would be cheaper to get a new boiler.It's only 5 years old!

tony, November 2010

Cheers for your reply Peter.When the heating is on the pressure goes into the red and loses water through the overflow pipe.By the time the heating goes off the pressure has dropped from 2mb(I have to top it up to 2 to make sure it's ok in the morning) to around 1mb.It's not hissing so that's a good sign.I have an heating breakdown insurance cover an am wondering whether to let it breakdown and call them out!

tony, November 2010

it sounds like it is the expansion vessal, whats the pressure like on the boiler when its cold? and does it go to 3mb when on for a few mins and leek out the over flow pipe out the back?is the boiler making any hissing sounds if so the heat exchanger is on the way out!or the pipe going to the vessel could be blocked down to dirt in the system, have seen it on all makes of boilers?

peter dublin, November 2010