Worcester Greenstar 28i - hot water temp/flow fluctuation

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3 Sep 2017
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United Kingdom
Recently purchased house with Greenstar 28i boiler - uncertain of the installation date. House had been unoccupied for ~ 10 months, but the boiler was serviced in Jan 2017 and was given the all clear.

At first the heating and water were fine. A few weeks in, the heating is still fine, but we have noticed that when running the hot tap, the temperature fluctuates between hot/warm to cold in approximately 30second cycles. We have also noticed that the overflow outlet on the outside of the house is dripping.

We did have a local engineer take a look and, within 2mins, he had concluded that it is most probably the diverter switch or the PCB. Given the boiler model, he estimated that the boiler was at least 10 years old and his advice was that a new boiler was the best option. He judged that finding the defective part may not be easy due to the intermittent nature of the problem, and may be 'trial-and-error' to correct the issue, which will be expensive with parts and fitting.

Do you feel that this is sound advice?

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