Four-port control valve
Selection of Control Valves in Variable Flow Systems (BG 51/2014) written by Chris Parsloe and published by BSRIA in June 2014, defines a four-port control valve (4PV) An actuated control valve with four ports (two inlet and two outlet) which varies flow through a terminal device by diverting a proportion of the flow through an integral “restricted” bypass avoiding the need for a separate piped bypass… Four-port valves are always designed as mixing valves but are commonly used in diverting applications.
It suggests that typical applications include; modulating control of heating and cooling, outputs from small fan coil units or chilled beams (typically up to a 20 mm pipe size) in constant flow branches.
--BSRIA
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