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Andrew Smith
Andrew Smith, Plumber
Category: Plumbing
Satisfied Customers: 3791
Experience:  City and Guilds qualified plumber
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Worcester Bosch Greenstar 30Di Combi Boiler. 8 or 9 years

Customer Question

Worcester Bosch Greenstar 30Di Combi Boiler. 8 or 9 years old. Serviced every year. Boiler started making a quick, high pitch squawk when hot water tap turned on. Any idea why?
Submitted: 6 months ago.
Category: Plumbing
Expert:  Andrew Smith replied 6 months ago.
How long after the tap us opened?
How long does it last?
Customer: replied 6 months ago.
Almost immediately after the hot tap is turned on and the high pitched sqwauking noise is brief. This noise should not be there. No sqwauking noise when cold tap used.
Expert:  Andrew Smith replied 6 months ago.
30CDi?
A combi - it could be a scaled up plate heat exchanger.
What's the temperature of the hot water like?
Customer: replied 6 months ago.
Temperature of hot water depends on where we have the setting. It's set at 3 just now which is fairly hot - bearable without having to cool it down with cold water.
Expert:  Andrew Smith replied 6 months ago.
Does it squeak more the hotter it us?
It sounds like the plate heat exchanger is scaled up and the water ways are narrower than normal creating the noise.
Customer: replied 6 months ago.
No. We don't have our water set any higher than 3. The squeak/sqwauking is only audible from the boiler when the hot water taps are turned on ... having said that, it doesn't occur every time. It's random. It is brief and doesn't happen at any other time apart from when we use the hot water taps.
Expert:  Andrew Smith replied 6 months ago.
Ok, I suggest you get your plate heat exchanger descale. If you ring 2 or 3 local people you should be able to get the best fixed price.
Customer: replied 6 months ago.
What does descaling this thing involve? Is it done manually? BTW l live in Scotland where our water is soft.
Expert:  Andrew Smith replied 6 months ago.
It can be every 12 months in s hard water area.
It needs removing and placing in a dealing solution for at least 15 minutes.
Expert:  Andrew Smith replied 6 months ago.
descaling
Customer: replied 6 months ago.
OK. Thanks. Not 100% convinced this is the problem. Worcester Bosch tech. dept suspect diverted valve is sticking!
Expert:  Andrew Smith replied 6 months ago.
It depends if you model has a hot water flow switch?
If not then the divertor valve needs to be fully open to fire the boiler for hot water.