USV valves are designed for manual hydronic balancing of heating and cooling systems. USV-I (red knob) is used together with USV-M to limit the flow in heating or cooling installation or can work separately as manual balancing valves for flow limitation. If certain pipe sectors do not require a control of differental pressure, USV-I and USV-M can be used as shut-off- and measuring valve. USV-M (blue knob) valve can be upgraded into an automatic USV-PV balancing valve. USV-M is designed for installation in the return pipe. Upgrading from manual to automatic balancing is done by mounting PV-controller to an USV-M valve.