By Eamonn Ryan
This article summarises key insights from a technical presentation to the SAIRAC Cape Town Centre in February 2026 by Johan van der Vyver, general manager: Belimo South Africa.
Belimo’s advanced actuator and valve technologies are helping shape smarter, more energy-efficient HVAC systems through improved airflow control, hydronic regulation and intelligent building integration. Belimo South Africa
At the heart of modern HVAC systems is precise control of airflow and water flow. Central to this are actuator technologies and advanced valves, which regulate dampers and hydronic circuits to optimise comfort and system efficiency. Belimo’s comprehensive air solutions portfolio includes rotary, linear and full-rotation actuators engineered to motorise air control dampers and slide valves across a broad range of applications.
ACTUATORS: FOUNDATION OF AIR CONTROL
Belimo actuators are the core of damper volume control in HVAC systems. Their product range covers:
• Standard rotary actuators for general damper control.
• Linear actuators for valve and slide applications.
• Form-fit designs for secure mechanical connections.
• Models with varying torque outputs (from small to heavy duty) suitable for everything from residential dampers to large industrial systems.
• Environmental ratings such as IP66 for operation in harsh or outdoor environments.
Many commonly used actuator types are available with higher protection ratings for demanding conditions, though not across the entire range.
A key safety feature in these actuators is the fail-safe mechanism, available in two main forms:
• Spring return actuators: internal springs automatically drive dampers to a pre-defined safe position (fully open or closed) during power loss – critical for applications such as fire and smoke control.
• Capacitor-based (supercap) actuators: store electrical energy to reposition the actuator during power failure. Unlike traditional spring return units, supercap actuators can move to specific fail-safe positions (for example, 10% and 50%) rather than just fully open or closed, providing more nuanced control for safety or HVAC sequences.
Regardless of mechanism, these fail-safe actions are single-action safety functions: once triggered by power loss, the actuator must be reset before normal operation resumes.
NEW DIGITAL GENERATION IS THE FUTURE OF SMART HVAC
Belimo is progressing towards digitised field devices with its New Digital Generation (NDG) platform, a step change in HVAC control technology. This evolution aims to make devices smarter, easier to install, and simpler to commission and manage over their lifecycle.
A flagship innovation is the Belimo Assistant 2 mobile app, which uses NFC (near-field communication). Crucially, this enables configuration and device-setting adjustments even when a device is unpowered – removing traditional barriers to on-site commissioning and troubleshooting.
At the core of this platform is Belimo’s proprietary M600 microchip, which delivers refined control, improved operational efficiency and quieter operation compared to legacy electronics. The custom chip strategy reduces dependency on external suppliers and strengthens Belimo’s ability to tailor device behaviour precisely.
Practical enhancements include:
• LED status displays on devices for instant visual feedback during setup and troubleshooting.
• Tool-free electrical interfaces, such as lever systems, that simplify wiring and reduce potential installation errors.
Overall, the NDG platform reflects the broader industry trend toward connectivity, intuitive diagnostics and enhanced performance in smart building systems.
TECH TALK
CONSTANT VERSUS VARIABLE FLOW SYSTEMS BALANCE SIMPLICITY AND EFFICIENCY
In chilled water system design, choosing between constant volume and variable volume approaches profoundly impacts energy use and performance.
Constant Volume (three-way valve systems):
Constant volume systems maintain a steady water flow through the coil circuit, regardless of cooling demand. A three-way valve either directs flow through the coil or bypasses it – but the total flow rate remains unchanged.
This design is:
• Simple and reliable.
• Lower cost at installation (no variable speed drives or complex control instrumentation).
• Stable for chiller operation, reducing risk of low-flow faults.
However, because pumps operate at full capacity even at low load, these systems are inherently less energy efficient, and bypassed water can result in a lower return water temperature (low ΔT syndrome), decreasing chiller efficiency. Variable loads are also more difficult to zone and control precisely in this configuration.
Variable Volume (two-way valve systems):
Variable volume systems regulate water flow to match demand using two-way valves. As demand falls, the valve partially closes and pumps slow accordingly, reducing energy consumption.
Advantages include:
• Higher energy efficiency.
• Improved comfort and load adaptability.
• Lower mechanical wear from reduced pump speeds.
Drawbacks include increased system complexity, such as pressure differential sensors and variable speed drives, and a need for more sophisticated control strategies to avoid chiller low-flow conditions.
Van der Vyver emphasised that the choice between constant and variable volume should be driven by the specific operational requirements of each building. The right balance of cost, complexity and efficiency depends on building profile and use patterns.
BELIMO BALL VALVES
Traditionally, ball valves were not used for precise modulation because of their rapid flow increase with small openings. Belimo’s Characterised Control Valve (CCV) changes this paradigm by integrating a characterising disc that shapes the flow curve to match an equal-percentage control characteristic.
This design means:
• A 50% control signal produces approximately 50% cooling capacity, reducing control ‘hunting’.
• Smooth and predictable modulation across the control range.
• Air bubble-tight shut-off, minimising leakage and energy waste compared to traditional globe or butterfly valves.
CCV valves are robust and self-cleaning due to the ball’s rotary motion, enhancing longevity and reducing maintenance.
From this foundation, Belimo developed the Energy Valve, which integrates:
• CCV ball valve.
• Ultrasonic flow measurement.
• Temperature sensing.
• Pressure-independent control.
• Energy monitoring.
The energy valve can measure flow, temperature and energy transfer across a coil in real time. This enables analytics and diagnostics via a building management system (BMS) or cloud platform, helping operators identify issues such as dirty coils or performance degradation.
A key feature is the Delta-T (ΔT) manager, which combats low ΔT syndrome by adjusting flow to maintain the desired temperature differential, improving both chiller and pump efficiency.
CCV FOR WATER APPLICATIONS
Belimo’s CCV technology valves deliver precision modulation with features such as:
• Smaller ball designs requiring less actuator torque.
• Equal percentage flow characteristics that ensure proportional system response to control signals.
• Air bubble-tight shut-off to prevent unwanted flow and conserve energy.
These features improve performance, longevity and maintainability in chilled- and hot-water systems.
PIQCV AND ENERGY VALVES
Modern HVAC water circuits increasingly use pressure-independent control valves (PIQCV) like Belimo’s, which automatically regulate flow independent of system pressure fluctuations. The PIQCV’s mechanical design maintains a set flow rate despite differential pressure changes, eliminating the need for manual balancing valves.
The Energy Valve builds on this by adding energy and flow measurement, and cloud connectivity. It uses ultrasonic flow sensing, temperature inputs and built-in logic to provide real-time data on performance, enable energy profiling and optimise chilled-water distribution.
CONCLUSION
Belimo’s actuator and valve technologies represent a comprehensive solution framework for modern HVAC control – supporting precise airflow and hydronic regulation, smart diagnostics, energy optimisation and adaptability for varying building demands. By combining robust mechanical design with digital connectivity and intelligent control strategies, these solutions contribute to efficiency, comfort and operational insight across installations.
