Solenoids
Solenoids can be thought of as an electronic tap, when electrical current is given to the coil (black box) it pulls the plunger in to solenoid body allowing water to flow from the inlet to the outlet. Solenoids are divided into two parts: coil (black body with electrical connections) and the body (brass section with either a flat or T-piece base).
Complete solenoids are interchangeable; however differing brand coils to bodies do not interchange.
2-way: Used to fill the boiler or as a replacement to a steam/hot water tap.
3-way: Used to activate the water for the group head, with the over pressure being released by the third spout, usually connected to the drain via a silicon hose, or brass pipe.