On my boiler, the domestic hot water has got cooler lately, although
the thermostat is turned up. I think the DHW heat exchanger needs
replacing, it has been done some years ago. I assume, these become
furred-up from hard water. Is it possible to soak them in large
volumes of kettle de-scaler and then re-use them? I never thought of
this before. any advice appreciated thankyou.