Zone valves control the flow direction into individual zones of hydraulic circuits (e.g. heating, solar thermal or cooling systems, water distribution etc.). Two-way valves are designed just to open or close individual hydraulic circuits, 3-way valves are sometimes called “hydraulic rail switches” which describes exactly their activity – a 3-way valve diverts the flow from one joint inlet into one of its two outlets depending on its state – if switched on or off. Zone valves are further classified by their use, max. and min. closing pressures, temperatures and fluid types, types of electric actuators and safety functions.