potterton profile leaking?

[dikybird]

Hi,

I have a Potterton profile boiler which is leaking from somewhere and slowly dripping through my ceiling, there is no visible water aroung the cylinder or the boiler or pipes, although there is a damp smell. It seems the leak continues when the heating and hot water are off.

What would it most likely be? the boiler? the cylinder? the pipes underneath?

thanks?