hi, my sime boiler has a problem with building up pressure. the hot water side works perfectly. however if the heating side is bled down so no pressure is in the system, after about 6 hours the system will be regestering 3 bar pressure and the safety valve will start releasing water.i have checked the top up valve and this is not leaking. can anyone suggest a possible cause ???

earle, March 2009

the same was with mine,check the 1 way vault ,its the 1 that lets the water in 2 fill the radiators up when pressure is low, its a silver connection pipe that connects the copper cold water pipes together. sorry idont know the name of it but it might be called a nonereturn valvue.

Grabo, March 2009