My 8 year old Baxi 105he appears to have a crossover between the hot water and heating system. When the heating is on the pressure goes through the roof and the pressure valve opens and stays open with a constant flow of water that can fill a bucket in an hour! When heating is off the pressure drops to zero over about 30 mins. Is this a cracked heat exchanger or can the two systems interact if any other part has failed?? Thanks

Steve c, April 2018

Thanks snorky you were spot on. Fixed in 10 minutes with a foot pump! So much for the “Engineer” that wanted to fit a new boiler for £1450!!

Steve c, April 2018

The expansion vessel is either flat and needs recharging or is perished and needs replacing. The pressure relief valve will need cleaning and maybe replacing. Get an engineer to visit..

Snorky, April 2018