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<blockquote data-quote="Channel Hopper" data-source="post: 925715" data-attributes="member: 175144">Issues again.Central heating has been perfect all along, but in the past few weeks the hot water has been getting more intermittent, with the overheat cutting in more frequently (requiring resetting).Having looked through the manual the diverter system pushes cold (and the new hot water) through the heat exchanger - not absolutely sure why - and onto the taps. However after a few seconds of the burner the pressure drops and the relief valve operates (again sometimes with the overheat).I thought the diverter diaphram may have given up the ghost after a few years of constant use and possibly the relief valve may be cutting in too soon, so both replaced tonight with no improvement.The pressure gauge does give some indication there is an excess of pressure before the boiler cuts out, and the gauge suggests repressurising when this happens, but I did check the expansion tank last time, and there was nothing wrong.So, is the fault with the heat exchanger ? or something else I have not worked out as yet ?(there's also a 'bypass' circuit mentioned, but I have no clue as to what it might affect, and appears only to be part of the central heating side of things.[ATTACH=full]77379[/ATTACH] )Diagram below for clarity.</blockquote>

[QUOTE="Channel Hopper, post: 925715, member: 175144"] Issues again. Central heating has been perfect all along, but in the past few weeks the hot water has been getting more intermittent, with the overheat cutting in more frequently (requiring resetting). Having looked through the manual the diverter system pushes cold (and the new hot water) through the heat exchanger - not absolutely sure why - and onto the taps. However after a few seconds of the burner the pressure drops and the relief valve operates (again sometimes with the overheat). I thought the diverter diaphram may have given up the ghost after a few years of constant use and possibly the relief valve may be cutting in too soon, so both replaced tonight with no improvement. The pressure gauge does give some indication there is an excess of pressure before the boiler cuts out, and the gauge suggests repressurising when this happens, but I did check the expansion tank last time, and there was nothing wrong. So, is the fault with the heat exchanger ? or something else I have not worked out as yet ? (there's also a 'bypass' circuit mentioned, but I have no clue as to what it might affect, and appears only to be part of the central heating side of things.[ATTACH=full]77379[/ATTACH] ) Diagram below for clarity. [/QUOTE]

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