I have had my boiler switched to dhw only through summer ,now its dropped cold but back to ch/dhw works fine on hot water but takes time to get hot and when ch on looses pressure so next day nothing works cos not enough pressure so have to refill to 1 bar. i have fitted a new relief valve but still same any ideas.

justin, September 2010

The pressure builds up so much with ch on that it expells through relief valve , fine in dhw mode .

justin, September 2010

i would check for leaks along the pipes and rad it maybe a minor leak

kash, September 2010