What is a Control Valve?

Control valves are at the heart of any modern HVAC system, shaping how energy moves through buildings and how comfort is maintained in occupied spaces. These devices are responsible for regulating the flow of fluid, adjusting in response to signals from a building automation system to match the heating or cooling demand at any moment. By precisely controlling how much fluid passes through, control valves help keep temperatures stable and energy use efficient. Companies like Belimo have advanced the technology behind these valves, integrating sensors, cloud analytics, and pressure-independent designs that take traditional flow control far beyond simple on/off functionality. Understanding how control valves work, what types exist, and how to select the right one has become essential knowledge for engineers and facility managers who want to ensure systems perform reliably while reducing energy consumption and supporting sustainability efforts.

A control valve is a device used in an HVAC system to regulate the amount of flow or direction (switching or diverting) of a fluid. It acts as the final control element in a control loop, typically operated by an electronic actuator that receives a signal from a Building Management System (BMS). Depending on the application, the valve may open, close, or modulate to maintain a target flow rate or temperature. The control valve’s role is critical to ensuring energy efficiency, comfort, and performance across hydronic and air systems.

A control valve responds to a control signal, which may be electrical (either analog or digital) or, in older systems, pneumatic. Modern HVAC designs primarily rely on electronic signals for precise integration with digital building management systems. The signal is sent to an actuator, which physically moves the valve to open, close, or modulate its position. By adjusting the size of the opening through which the fluid passes, the valve changes the flow rate to maintain the desired set point. The valve’s flow capacity is often represented by a flow coefficient (Cv), or gallons per minute (GPM), which helps engineers select the correct valve for a given system.

Control valves are available in various types, each offering specific advantages depending on the system requirements. A globe valve has a linear motion design that provides precise control, especially in applications where flow throttling is important. A characterized ball valve operates with a quarter-turn mechanism, making it ideal for both on/off or modulating control, particularly where a tight shut-off is essential. A butterfly valve provides a space-saving alternative for larger pipe diameters and is well-suited for on/off or modulating control.¹ A pressure-independent control valve maintains a consistent flow regardless of system pressure fluctuations. Pressure-independent control valves come in both mechanical and electronic varieties.

Belimo offers an industry-leading valve portfolio for commercial HVAC systems, delivering precision, reliability, and flexibility across a wide range of applications.

Here’s a breakdown of the key categories:

Characterized Control Valves (CCVs): These valves combine the leak-tight performance of a ball valve with the modulating precision of a globe valve. The internal characterization disc modifies the flow profile for predictable control, making CCVs ideal for variable flow systems. High-temperature versions (HTCCV) are used in applications like steam or hot water.

Pressure-Independent Valves: Belimo offers several types, including the PIQCV (mechanical), the EPIV (electronic), and the Energy Valve (electronic), which adds IoT functionality with cloud integration, flow and power control, and delta T management. These valves ensure precise flow regardless of pressure changes, which eliminates the need for separate balancing valves.

Ball Valves: Belimo’s ball valves cover both standard and high-temperature applications, and are available in two-way and three-way configurations.

Globe Valves: Belimo globe valves provide accurate control with linear and equal percentage characteristics, well suited for retrofit applications.

Butterfly Valves: Butterfly valves are used for high-flow applications and large pipe diameters. Belimo butterfly valves offer a compact footprint and fast actuation, with options for on/off or modulating control.¹

Six-Way Valves: Belimo offers two types of six-way valves for four-pipe systems such as chilled beams, radiant ceiling panels, and fan coil units. The six-way characterized control valve (6-way CCV) uses a single actuator to switch between heating and cooling circuits, combining the functionality of up to four two-way valves and one 3-way switching valve to simplify installation and reduce component count. The six-way electronic pressure-independent valve (6-way EPIV) includes all the capabilities of the 6-way CCV, but adds advanced features such as pressure-independent flow control, integrated ultrasonic flow measurement, BACnet, Modbus, and MP-Bus communication, and support for optional condensation sensors. It also eliminates the need for manual balancing valves. This makes the EPIV a smart, data-enabled upgrade for systems requiring higher precision and connectivity.

All Belimo control valves are available with a variety of control signals that enable functionalities such as modulating, 2-position, and floating-point control. Some models also support bus communication and integrate easily with building automation systems.

The Energy Valve is Belimo’s most advanced offering. It is a pressure-independent control valve that combines the measurement of flow and temperature to optimize power for efficient heating and cooling. With its integrated sensors, the valve can modulate to meet a specific heating or cooling load, helping facilities reduce energy waste, maintain target delta T, and maintain overall system performance. Using Belimo’s cloud-based analytics, it also supports predictive maintenance and provides detailed visibility into energy usage, helping buildings meet their sustainability goals through smarter, more efficient operation.

For pressure-dependent valves, sizing is based on the required flow coefficient (Cv), which is the flow capacity of a control valve at fully open conditions relative to the pressure drop across the valve. Cv is calculated using the formula shown below.

For pressure-independent valves, selection is based on simply matching the valve’s rated GPM to the coil’s required GPM.

Actuator selection depends on the type of control signal required and whether fail-safe functionality is needed to ensure proper valve operation during a loss of power.

Belimo provides sizing and selection tools to help ensure correct configuration for any project.

Control valves are critical to system performance, and Belimo has designed a product line that covers nearly every commercial HVAC need. Whether you are looking for a traditional globe valve, a CCV, or a smart, IoT-enabled Energy Valve with built-in analytics, Belimo offers a solution that simplifies design, improves control accuracy, and lowers long-term energy costs.

¹ Butterfly valves typically modulate effectively only within a limited range, generally between 0° and 60° of rotation