Greenstar 28i Junior mk V - Hot water issue

[mudd786]

Hi

In central heating the boiler is absolutely fine.

When we run any hot water tap you hear a whining sound from the boiler much like water running through or past a blockage.

As you increase the flow on the tap it starts to cause a vibration in a pipe, I assume, which sounds like a drum beat (dub dub dub dub best I can describe it lol).

The frequency of this can be changed my increasing the flow, this increases the rate of the sound or decreasing the flow which reduces the sound.

If you keep the flow slow you avoid the sound and if you open the tap fully you eventually get past the resonance and the sound disappears.

If you open the cold tap while the hot is running that will reduce or eliminate the sound also i'm thinking this is due to the mains pressure falling which runs through the boiler.

I was wondering if anyone could shed some light on this please driving us mad. The whining sound made me think maybe a deposit in the turbine or that area ? or possibly the turbine has broken down causing a obstruction ?

Any thoughts suggestions appreciated!

Cheers

 

[mudd786]

A friend who is a heating engineer suggested could be a thermostatic shower cart of which we have two. So I purchased brass end caps isolated water removed the bath one first which is used the most and where the sound seemed to originate from.

Terminated hot and cold with brass end caps opened up the mains let the water flow purging air from all outlets ran hot water as we would normally no sound whats so ever so the sound was created from a bad thermostatic tap.

Hope it helps someone else down the line.

Cheers.