Lots of noise when hot water tank fills up? advice please

1 Mar 2011
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West Glamorgan
United Kingdom

We have just bought a new house and we have just had a new boiler Worcester Greenstar 30 CDI system boiler along with a new tank in the loft which replaced two galvanised steel tanks in the loft. The previous boiler was a floorstanding stalrad boiler which was on its last legs.

Originally we were going to go for Greenstar 24ri regular boiler but when they were doing the work they found out that the previous boiler ran two seperate feeds for the downstairs and upstairs (I think thats what they said) so we had to go for a system boiler

However what we are finding is if we run hot water say for 5 mins if we are washing our hands or rinsing dishes there is a tremendous noise coming from the tank in the loft or pipework as it fills back up with water.

Also when the hot water is on the system seems to make a loud whirring noise that seems to be coming from where the boiler room is

Is this normal or has it been installed incorrectly? or are there new valves on the market that can reduce the noise? I am going to call them (installers) tommorrow to see what they say but would appreciate any advice so I am prepared.


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The noise in the loft could be the ball valve needs cleaning/changing.
The loud whirring noise, where is it exactly?
...replaced two galvanised steel tanks...

Did your installer cap off a water main supply tee to either of these removed tanks leaving a dead-leg, rather than removing the tee completely? If these dead-legs fill with air you can get water hammer - very loud, rhythmic knocking.
Rigid galv. tank replaced with not so rigid plastic one - mains water pipe not clipped any more than when galv. tank helped support it --- water hammer - simples ;)
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Thanks so what is the resolution - to clip the mains pipe in - what would you clip it onto?

The plumbers who installed the system are coming back Monday to look at fixing the problem.

We are not in the property at the moment as its being renovated - but did some more investigation tonight.

Had the hot water tap running and lone behold the noise started - the pipes in the airing cupboard were very noisy along with the cold expansion tank in the loft when refilling with water.

Also my hot water pressure is far lower than my cold water pressure - is this related or is this another problem that they need to solve.
Well I`d clip it onto any wooden structure in the roof near enough - but there probably aren`t any ;) so I`d make up noggins and struts off the timbers . Diferential in H+C pressures - maybe cold is mains fed :confused:

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