scale in plate heatexchanger and can be cleaned, No need to replace it.
k
May 2010
we just had the same problem,turned out to be scale on the heat exchanger,failing that it could be the exchanger broke,or the valve that switches between the rads and hot water.gas man charged me £50 and took an hour but he did say the exchanger was about £150 if that had gone
mikec
May 2010
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