Worcester Highflow anomaly

I have recently had installed a Worcester Bosch Highflow 400 combi boiler and have noticed that when a cold tap is run in the house the boiler HW demand indicator lights briefly. Has anyone else noticed this. I assume it's due to the drop in pressure on the cold water inlet fooling the boiler into thinking there's been a demand for hot water - the hot water demand is detected by a flow turbine in the cold water inlet so maybe it runs backwards enough to trigger the boiler? Anyone else experiencing this. The Worceseter technical helpline thought that my explananation was unlikely but I can't think what else it can be.
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Wouldn't it have been better to have fitted a proper bleed valve - or even a ball isolator valve?
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Regards

John


"R. Simpson" < snipped-for-privacy@removethisargonet.co.uk> wrote in message
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Thanks for the responses. True enough it was due to a "dead leg" of pipe. Our house is an ex B & B with basins in all the bedrooms. I found that one of the taps hadn't been vented hence there was a leg of compressed air forcing the water back when the cold tap was turned on elsewhere in the house and thus fooling the hot water flow sensor. It's nice when there's a logical explanation and I'm surprised that the guys at Worcester hadn't heard of it.
Regards,
Trevor.
wrote:

HW
assume
this.
unlikely
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