Any detectives out there ?

[stevebamford]

Hi All,

Anyone fancy a detective job?

Our system has a Santon unvented cylinder and sometimes we get this strange metallic juddering noise when the hot tap is first turned on.

Always happens first thing in the morning - then intermittently during the day

Sequence is this

1) Turn hot tap on
2) Get very high flow for maybe half a second
3) Then the noise
4) Flow drops back - still fine but less than it was

You can listen to the noise here (if the link works)

http://www.hamiltonit.co.uk/Tools/Judder.mp3

I have narrowed the noise down to somewhere near the cylinder if thats any help ..

Any ideas ?

Would it be useful to get some piccies of the setup ?

ta

steve

ps And yes I have asked the installer - he is supposed to be coming round next week to have a look - problem is the noise is very intermittent

 

[gas4you]

Could be muck in the strainer in the multi-function valve. These should be removed and cleaned annually when the cylinder is checked over.

 

[Onetap]

1) Turn hot tap on
2) Get very high flow for maybe half a second

Normal. The pressure increases as the water heats up, so the pressure in the cylinder exceeds the mains pressure.

3) Then the noise

Probably the non-return valve or pressure reducing valve chattering. Usually comes as an all-in-one combination valve. Has the inlet strainer ever been cleaned? TRy that, if not replace the combination valve.

4) Flow drops back - still fine but less than it was
Normal

 

[cider]

get the installer to check the pressure in the exp vsl. It may be too high and the noise is air trapped in bottom of vsl and being pushed back into pipework as soon as the tap is run.
the initial surge of water comes from the exp vsl as this builds up pressure during expansion of wtr heating.
the problem could be made worse if the incoming pressure is poor.
Also check for american bull frog living under the tank.

 

[stevebamford]

Thanks guys - reassuring to know its nothing dangerous !

Its a new system (6 months old) so not sure what if any cleaning was done

It sounds like the noise is coming from one of these widgets attached to the cylinder

pictures zapped - please see below

Thanks again

Steve

ps sorry the pics are so BIG !



[/img]

 

[WDIK]

Untitled

• WDIK
• 8 Jan 2009
• 1

Untitled

• WDIK
• 8 Jan 2009
• 1

 

[stevebamford]

Thanks WDIK - they're a bit more manageable!

The chattering noise has been happening ever since the system was installed so is it possible the pressure relief valve just was never set correctly ?

ta

 

[stevebamford]

CIDER you are the winner !

Mr Santon came round fiddled with the expansion tank (apparently it was the daiphram vibrating too rapidly)

Bizarrely he turned the expansion vessel upside down ... and replaced the rigid copper with a flexible hose

And that seems to have sorted it

Thanks for the replies guys - excellent thread