HELP - Loud Hot Water Noise

[Spinny]

I have had a plumber here today who has repressurised my expansion vessel on an UVC system back up to 3bar.

Unfortuately he left for the day and is now uncontactable but we have a problem.

Every time we run off hot water we are getting a very loud creaking noise from the system.

 

Any help or advice on what may be going on and how to resolve it ?

[John Carroll]

Is this the first "creaking" problem?

Did your plumber de pressurise the UVC before repressurising the EV?

What make of UVC? 

What are the capacities of both the UVC and the EV?, should be labeled on both.

[Spinny]

Thanks for response John.

Yes this is the first creaking/groaning problem.

Did the plumber de pressurise the UVC ? Not sure. I think the water was turned off at one point though, so perhaps.

The UVC is Gledhill Stainless ES 250L, the expansion vessel is a Zilmet, nominal volume 22.

 

The plumber's colleague has since returned. Said the noises were because of some kind of flutter/oscillation from the pressure reduction valve. He let some air out of the expansion vessel to reduce the pressure in it somewhat - didn't have a pressure meter - so not sure of expansion vessel pressure now. This has stopped the loud creaking/groaning noises whenever we ran the hot water.

 

The system has had release through the tun dish on a regular basis over 3 months or so, relieved by running off hot water through the taps when spotted.

 

The plumber is proposing to replace the pressure reduction valve (currently a Caleffi) with a new 28mm pressure reduction valve, having suggested this may help improve flow through the system.

 

Mains pressure is about 3.5 bar.