A Control Valve is an actuated device that modulates fluid flow in HVAC systems to regulate temperature, pressure, or humidity by responding to control signals. Control valves are essential components that enable precise environmental management in heating, cooling, and humidity systems.
Types and Operation
Control valves include two-way valves (on-off or proportional flow control), three-way valves (diverting or mixing flow), and specialized designs like balancing or check valves. Valve actuators receive 0-10V or 4-20mA control signals and position the valve stem to modulate flow rates between 0 and 100 percent. Flow coefficients (Cv values) typically range from 0.5 to 100 depending on line size and application requirements. Fail-safe positions (spring return to fully open or closed) protect systems during control power loss.
System Performance
Properly sized and controlled valves prevent temperature overshoot and hunting by maintaining stable flow rates. They enable zone-based temperature control in multi-zone systems and support seasonal changeover between heating and cooling modes. Valve response time (typically 30-120 seconds) affects system stability and comfort performance.