i work on these quite a lot so here's some info for you,
no hot water unless the heating's on says to me that the diaphragm in the divertor valve has perished and isn't making the microswitch, although the microswitch could have come loose or itself be broken!
don't worry about condensation it's not relevant to your boiler
the noise could be one of 3 things
1 the main heat exchanger is limescaled up and restricted making a loud humming/wailing type sound
2 the circulation pump is on its way out
3 the combustion fan is on its way out
without hearing the noise it's difficult to guess!
heat exchanger-£300ish fitted
pump -£120ish fitted
fan-£120ish fitted
the prices i'm quoting are what we would roughly charge for this kind of work not including vat! also bear in mind that your system might need to be de-scaled and inhibited with chemicals if there is a scale problem! alas... the longer you leave it the worse things are going to get and can end up ultimately costing you even more money as other parts are affected by the faults!
phill
February 2008
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