Electric shower knocking

[Jimbo]

Greetings,

I have a Triton Rapide II electric shower, fed from the mains (branching from the bath cold water supply).

I installed it 6 months ago, and recently it has started making knocking noises during operation. These started out quite quietly, but are now getting quite loud. It almost sounds as if the water is boiling inside the cylinder. The supply pressure seems to be fine.

Does anybody have any idea what might be causing this problem? I'm reluctant to disconnect it all and take it back to the shop for an exchange unless I'm fairly sure it's a problem with the shower unit itself.

Has anybody else had this or a similar problem and can give me some advice?

Thanks

Jim

 

[Jimmy]

Check the security of the pipe fixings as this can cause the problem, if still no good a slight reduction in water pressure achieved by closing the stop valve supplying the shower a fraction may do the job

 

[Jimbo]

The pipe fixings are fine. The water pressure is unchanged since installation, and the problem has only recently started about two weeks ago.

When you switch the shower off, for about two seconds there are boiling sounds, like in a kettle that has just boiled and clicked off. However, the water that comes out of the shower head is normal temperature.

I'm wondering if air is getting into the system somehow and causing cavitation? Anybody got any ideas??