Since I moved in the house, initially thought it was the GF pump (but I listened with metal rod and thats running quiet), isolated all its pipes and worked upto this little devil which appaers to be the orogin of the noise which travells down the pipes. Annoying in the loft when in bed!!
I have a vented conventional boiler / hot water cylinder central heating system. My boiler (baxi Solo) is in the loft.
Between my pump (in the cylinder cupboard) and the two water pipes going to the boiler (at the junction where the expansion pipe goes up to the small header tank) is a silver...