I recently had my bathroom tiled, in the process the builder took the radiator off of the wall, after refitting it my hot water kept running hot, then cold, then hot, i questioned him on this and he said the boiler pressure had fallen when he removed the radiator, he came back and increase the pressure using the pressure valve, since the hot water has been fine but now the boiler pressure keeps rising even when the CH or water is not in use, usually 1 bar in 8 hours, i then have to bleed the radiators to reduce the pressure but 8 hours later it has increased, when it gets to around 3 bar i panic, we have had a corgi guy out and he serviced the boiler and removed a loop that connected two pipes, he said it was not needed once the system was full, we thought this may have cured the system but it is still rising at the same rate if not slightly quicker, i have spoken to my builder and he says its the pressure valve? i have read some similar questions and could it be my heat exchanger?

Lee, October 2007

Sorry forgot to mention that if the CH is on and we try to use the hot water the pressure gauge on the boiler flicks up and down like mad and there is a load kind of knocking noise, but this doesn't happen when we use the hot water when the CH is off and similarly if we use the CH and no hot water there is no sound, is this related to the constant pressure increase?

Thanks for the offer Colin but im in Chelmsford, Essex.

Lee, October 2007

Probably the plate heat exchanger allowing mains water into the system - renew it if you are within 40 miles of canterbury we could do it for you 07961 316003

Colin, October 2007

could be the secondary heat exchanger mains water going through it going into the heating circuit. Try turning off the mains water in to the boiler and see after a little while whether the pressure has stopped rising. the other possibilities could be that the expansion vessel is flat and needs repressurising.

andy, October 2007