Unvented HW Range Tribune banging noisrs.

[wedge69]

We have a very strange problem that I hope someone can help me with.

We have an unvented hotwater system with a Range Tribute HE tank. We give our little boy a bath every night, and turn the hot water bath tap on. After a couple of seconds of running the hot water we get a really loud banging/hammering noise that lasts for a couple of seconds. It seems to me to be coming from somewhere in the mass of valve things inside the cupboard near the tank. If you grip the cold mains inlet you can feel the vibrations.

If you run the sink hot tap first, then turn that off and run the bath hot tap then the noises don't happen. It happens every time with the hot bath tap but has also once or twice happened with the shower.

Anybody have any clue what the problem might be? Any suggestions appreciated as it is driving us crazy!

 

[Dan Robinson]

Either loose pipes or the expansion vessel charge needs adjusting

 

[wedge69]

Thanks.

Which pipes? Something burried under the floor?

I just don't get why it only does it the first time you turn the bath tap on. If you turn it off and back on again then it is fine.

 

[wedge69]

Just for my understanding if a professional wouldn't mind explaining, why would a drop in pressure cause noises in the valve pipework?

I guess what confuses me most is if why we run a different hot water tap first before the bath hot then the problem doesn't happen. Is it because the bath has the fastest flow and so would somehow cause the greatest pressure change or something?