Four-way mixing valve (cross valve) is used for control of liquid or gas flow. It has four ports - that is four locations for connection of pipes. It is mainly used in the central heating systems for setting temperature of heating water and domestic hot water and to increase the temperature of water returning to the furnace.
It can be used in all types of boilers, mainly for boilers fired with solid fuel with automatic or manual charging and for all heating systems.
Four-way valve lowers operating costs and it connects two functions: