I have a Potterton Puma 80e combi boiler approx 8 years old which seems to be working fine other than the external overflow (if that's what its called) has gone from dripping all the time to a larger quantity of water coming out - not buckets but enough for there to be a wet patch underneath the pipe all the time. Can't find any mention of its purpose let alone a reason in the manual.
Whats the pressure reading on the dial on the boiler?
If its more than 2 bar you need to let some water out as the pressure relief valve is operating. Is the filling loop connected? Is the valve open just a little bit thus overpressurising the system?
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