Keith Curtis
Hi, Leak's on a boiler are a bit difficult to diagnose with out being able to look at it in person. If you have a condensing boiler and you'll know this as when the boiler is working you'll see lot's of steam coming out of the flue, your leak might be something to do with the condense. What happens is that when the boiler is working it produces waste water from the flue. This then builds up inside the boiler's condense pot and is expelled. Hence this can only leak when the boiler is working. Have a look for a white plastic pipe at the bottom of the boiler, this is the condense line for the boiler, if the water is coming from this area it's probably that. Hope this helps
