Terrible noise from pipes in loft

[Ardmark]

I sometimes get an unbelievably loud grinding / banging noise from the pipes in my loft - it seems to originate at the cold water tank. It sounds like a really loud hammer drill, but you can actually feel it through your feet! It lasts for between a few seconds to about half a minute, and I'm worried something is going to break catastrophically if I don't do something about this.
Does anyone know what causes this, and what can be done to fix it - is it just a bad ball valve or air in the pipes? Would a water hammer arrester solve the problem?
Thanks in advance.

 

[Whitespirit66]

I would start by looking at the float valve in the cold (large) water storage tank in loft. Worth trying a new valve, or you could first try isolating water supply to the valve and seeing if you can still make the noise happen.

 

[Ardmark]

I would start by looking at the float valve in the cold (large) water storage tank in loft. Worth trying a new valve, or you could first try isolating water supply to the valve and seeing if you can still make the noise happen.

It's difficult to predict when it will happen, so I guess I'll try a replacement valve and see if that fixes it. Thanks.

 

[HERTS P&D]

See below:

http://www.screwfix.com/p/pegler-prestex-float-valve-part-2/27627

Andy

 

[Ardmark]

See below:

http://www.screwfix.com/p/pegler-prestex-float-valve-part-2/27627

Andy

From the reviews it looks like it's worth trying so I'll get one and fit it this weekend.
Thanks!