rattling/buzzing from immersion heater

[separation]

When I open the hot water tap and let it run for a short while, I get an awful rattling/buzzing coming from the immersion heater and it stops when I open the cold tap. What is happeneing?

[grahamfreer]

Probably your ball **** in main header tank

[LATECOMER]

When you open the hot tap water leaves the cylinder and is replaced via the header tank so water is flowing thro the mains pipe into the header tank.Sometimes the force of the water causes water hammer or just vibration. When you turn on the cold tap you change the pressure a little and the vibration stops. For a quick cure try this, turn on the hot water till the noise starts than grab hold of the pipe making the noise, if the noise stops the put a bracket there or just jam summat between the pipe and wall/cylinder. Not a big problem really

[markja]

try turning down the flow of water into your immersion. there should be a stop valve between your tank in the loft and your immersion.don't fully close it, just a little may suffice, it will slow the water down and reduce the tendency to bang and knock.