Pipes

The in and outlet tubes on espresso machines can be found in various shapes and sizes. These tubes are in most cases made from copper with brass fittings soldered to the ends of it.

A brewing group has in most cases, a feed tube and a return tube, this is for instance the case with a Faema E61 espresso machine. The feed tube comes from the top of the boiler heat exchanger (HX) and the return tube goes back to the bottom of the HX.

But when you have a La Cimbali espresso machine the inlet tube goes trough the group, through the HX and then out of the brewing group. These brewing groups do not have a return tube in the brewing group. This is just being discarded.