Description

Original La Marzocco expansion valve.

The expansion valve limits the maximum pressure in the coffee boiler. Pressure is created during the heating & expanding of the water. The expansion valve consists of a valve seat, a spring and a barrel body. The tension on the spring is set by loosening or tightening of the barrel. More tension (clockwise) makes a higher pressure setting. At the set pressure, the valve will open and water will be released (usually dripping) to the drain box. Pressure should be set at or near 12 bars.