I have a Vaillant combi boiler and when i put on the CH water is dripping from a pipe that looks like an overflow pipe going from back of boiler to outside wall.Does anyone have an idea what the problem might be.Thanks

jane, May 2010

is this a condensing boiler ecotec or ecomax boiler.
if it is this is normal for water to flow from CONDENSATE pipe, as its condensing...otherwise if out of the Pressure relief valve, could be expansion vessel down on air pressure or dirt in seating of prv.

ant, May 2010

Sounds like the safety valve is either indicating a problem or just leaking. Does the pressure gauge go up soon after lighting the boiler? If so the expansion vessel could have failed. I suspect you are regularly topping up the system. If the pipe leaks whilst the system is cold as well then the safety valve is leaking. If only when running them most likely the expansion vessel. (Replacement is £100 - £150 I'm afraid)

Paul Thurmaston, Leicester, May 2010