On Friday, February 13, 2015 at 8:22:04 PM UTC, charles wrote:
I was getting localised boiling (kettling) in my GlowWorm boiler when the
pump turned off. I've added ScrewFix Boiler Noise Reducer and that problem


Are you in a hard water area? Could be accumulation of limescale caused by failure or lack of additives or just many years use. Can be fixed by Furnox descaler though it's a bit of a hassle.
My boiler tends to sound like my 3KW electric kettle when it's furred up.

rusty