First post on here for me although I'm a time served electrician I know my way around the older control central heating systems. My own above boiler has developed a hot water supply problem but the heating side is fine and my boiler has given me great service for 8 years. Problem is fluctuating hot water temperature when called for. There are no error codes showing on the diagnostic read out and symptoms are when the hot tap is turned on the boiler fires up as normal and heated water flows but not as normal, running warm then cooler at regular short intervals. I then let the boiler and heating side totally cool down before selecting hot water only then I turned on the hot water tap. Observing the boiler then it fired up fine and the water temperature read out rose to around the 85-90 degree mark before cutting out for a while then firing back up. This cycle repeated whilst the water temperature flow coresponded with the boiler action. My own conclusion is that the diverter valve has developed a fault as the heating flow pipe is getting hot below the boiler despite the selector switch being in the hot water only position. We live in a soft water area so I doubt whether the heat exchanger could be furred up (been reading a few posts). Any thoughts/ diagnosis off you most learned guys on here ???
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