How can I stop my boiler starting up when I turn my cold water tap off.It doesnt seem to ignite but is Purging i have bben told.I had a non return valve fitted on the cold water pipe supplying the tap in question but it made no differance Its a potterton boiler and is about 2 years old.Its driving me nuts.Its a potterton Combi H.E Plus

Ian C, August 2010

You need to fit the double check valve on the cold water inlet to the combi not the tap. May also need a domestic hot water expansion vessel fitting.

Sean, August 2010