Hi,
My Glow worm Energysaver boiler starts to resonate when Full hot water is demanded, it sounds like a noisy car on tick over and there is a slight smell of gas. It's not water hammer, it's combustion related, maybe the gas valve is defunct. Once it's power cycled it runs ok providing you don't open the hot tap to full. Central heating is working ok.
Thanks,

Any suggestions?

John, January 2010

If you have a gas leak the sensible option is to get the gas board in especially if you can still smell gas when the boiler is off.

Tommy Long, January 2010