heating boiler drops pressure?

Swift combi boiler builds up pressure after a short while either firing or standing still . I have to release safety vave to ease pressure. Do I have to replace water pressure switch or the elecrical compoments what way Iam able to find out .Is it somthing else not related to what think it is.
thanks

frank
July 2008

It sounds to me like a faulty expansion vessel on the boiler, they can be recharged with a pump ( normally like a car valve) or it maybe punctured inside the vessel which means you will need a replacement.They are quite awkward to fix, id get a pro in who knows swiftflos, they can be fiddly.

PK1
April 2008

hi, i had a similar problem, there were a few problems one was there was dirt in sum of the pipes and also if you have an open and shut valve keep it shut after you have put the pressure back up.

mr trevor sparkes
April 2008