17 2 08 First visit by BG engineer. Diagnosed Actuator which is part of the Diverter Valve. He had to order the part so arranged another visit.
19 2 08 Return visit by same engineer. Fitted actuator but then said the micro switch/flow switch needed replacing. He also said the diaphragm in the expansion unit was defective as he noticed the pressure going over 3 bars quite soon after the heating was switched on. I had not noticed this before so wondered whether he had caused this in some way. We had heating but no hot water that evening.
20 2 09 BG engineer (different one) came and more or less had to start from scratch to diagnose the problem. He seemed very experienced and fitted the microswitches, new PCB and diaphragm (not the one in the expansion vessel). He thought the latter diaphragm was OK but I agreed to keep an eye on the pressure. He explained about the i on the 28i name of the model and suggested I turned off the water preheat as he felt this caused more problems than advantages offered. So the above work was undertaken by 2 engineers over 3 visits - approximately 7 hours - with new parts fitted - at a TOTAL cost of £127. I have no complaints whatsoever as you can imagine. However, I will continue to post just to let everyone know whether the problems have been resolved. This morning (Saturday 21 Feb )I had to run the tap in the kitchen for about 5 mins before hot water came through. Obviously this is due to the pre-heat being switched off. I might decide to switch it back on.
I hope this has been of some help but will continue to post as I think sites like this are very helpful, particularly for women like me with no technical knowledge, but who have to make the decision as to whether to call out an engineer or not.
dottie49
February 2009