Hi rob, I think it is steam starts after the tap has been on and carries on after the tap is off. The boiler actually sounds like a kettle now when it is heating! Still seems to work just sounds very sickly.
Hi I wonder if anybody is able to offer some advise please, I have a Potterton Puma 100e combi boiler and today when the hot water is being run there is air escaping from the Automatic Air Vent. The boiler is serviced and the AAV was replaced about 4 months ago by my friend who is a plumber...