Now here's the thing:
When my CH boiler (a Potterton Suprima) fires up for a long period (such as first thing in the morning), after a few minutes it starts making 'wheezing' sounds. Occasionally, this turns to rattling in the pipes which can reverberate through the house (especially through to the header tank which is in the loft directly above my bed). The pipes rattle for a couple of minutes until I hear an almost orgasmic spurt into the header tank.
From all the descriptions I've read, this sounds like 'kettling'. Conventional wisdom seems to be to raise the pump speed to get the water away from the heat exchanger quicker. However, this rattling was only occurring when the pump was on its highest setting, and when I lower the speed of the pump, it doesn't occur. The wheezing sound is still there, though.
Could I have a problem other than kettling? Could it be related to the pump?