Worcester 28SiII Loud Whistling Noise

3 Oct 2007
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United Kingdom
Hello all,

I have a Worcester 28SiII which has started making a loud whistling noise. The boiler is 3 years old. I first noticed the noise after the timer had just turned the heating off. I turned on a hot tap and the boiler lit and the noise stopped but as soon as I turned the hot tap off the whistling started again. I also noticed that when I turned on a cold tap the noise from the boiler also stopped, only to come back as soon as the cold tap was turned off. I tried turning off the boiler completely but the noise persisted. Then I turned off the cold water inlet on the boiler and the noise stopped. So since then I have left the cold water inlet on the boiler turned off, the heating still works fine but obviously I can't get hot water! With the cold water supply turned on and the central heating OFF the noise is constant and loud, with the central heating ON the noise is intermittent and quieter.

Has anyone come across this problem before or have any idea what could be causing it?

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It depends on when and where the noise occurs.

It can be caused by any sharp change of direction in a water or air flow.

If its only on DHW then its usually as a result of the rubber element in a flow restrictor ( regulater ) in the cold inlet.

Thanks for your quick reply Tony.

In answer to your question about when and where the noise occurs, it seems to be coming from the hot water flow inside the boiler and occurs more or less constantly when the central heating is off and there are no taps calling for hot water. I have also noticed that the noise seems to build up and then the boiler fires up, even though there are no taps calling for hot water, the boiler stays lit for a few seconds and then goes off and the noise dies away for a few seconds then starts to build up again and the cycle is repeated.
It sounds as if there may be a false demand for hot water.

I went to a Worcester Junior this week which has been described as making a noise when no DHW or HW was being demanded.

When I attended it did not make that noise but had a problem because the condensate drain was blocked.

Are you sure its not still under guarantee?

have you called the installers to it?

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I don't think it has a condensate drain as it's not a condensing boiler. It isn't under guarantee as it is just over 3 years old. I have just spoken to the installer and he also thinks the problem could be with the flow restrictor in the cold inlet.

Thanks for your help.
Quite a clever installer then to know that!

Unless you told him what I had said and he just agreed!

Its called a Domestic water flow turbine.

Quite a clever installer then to know that!

Unless you told him what I had said and he just agreed!

:rolleyes: Installers can also fault find Tony ;)

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