My 3 year old boiler has gone on the blink. Initially there was no Hot Water on demand. Pre symptoms, I had been away for a week and as always, I'd put the preheat control to OFF to save short cycling? The Preheat is normally set to the 6 o/clock position. I tried opening the Hot Water tap (sink) to its fullest etc, without any change.
I have found out a way of getting hot water, but it is a bit of a pain and not a long term solution. If I return the preheat selector to its Off position then immediately turn it to 6 o/clock, the boiler kicks in and during this period, turning on the hot water tap keeps the boiler in operation and hence hot water continues to flow without interuption. After the boiler goes back to its steady state the preheat function does not kick in at all to maintain its preset temperature and the indicated temperature slowly declines to zero.
I've tried resetting and even repowering up after isolating the mains supply, both make no difference.
I've tried the central heating part of the system and it appears to be operating fine.
Any suggestions appreciated.