INTELLIGENT CONTROLS DRIVING MISSION-CRITICAL COOLING PERFORMANCE
RACA Journal I June 2026 www. refrigerationandaircon. co. za 21
CONTROLS
Supplied by SAIRAC Cape Town Centre
PLC PROGRAMMING WITHOUT THE MYSTIQUE To further demystify PLCs, Milne demonstrated basic programming using the Eliwell Free Studio Plus platform. Rather than focusing on complex code, he showed how function blocks can be arranged in a way that closely resembles traditional wiring diagrams. Logic flows from left to right and top to bottom, making it easier to understand and fault-find.
A simple thermostat was built step by step, incorporating a temperature setpoint, an analogue input, a calibration offset, comparison logic and a digital output. Simulation tools allowed the logic to be tested in real time, providing immediate visual confirmation of how the system behaves.
While acknowledging that a simple on-off thermostat is insufficient for most real applications, Milne used the example to introduce more advanced concepts such as differential control and PI( Proportional-Integral) regulation, which are already embedded in many standard controllers.
Modern controllers rarely operate in isolation. Modbus communication allows controllers to exchange data with monitoring systems, energy meters and other devices. Each variable and parameter has a defined address, enabling integration without proprietary lock-in.
Monitoring systems provide historical trending, remote access and powerful fault-finding tools. However, Milne cautioned that these capabilities can also create unrealistic expectations of support, particularly when contractors rely on suppliers as a first point of troubleshooting rather than consulting documentation.
THE DANGER OF UNMANAGED CUSTOM CODE One of the most sobering messages of the evening concerned the long-term risk of custom programming. When programmers or commissioning technicians move on, undocumented logic can leave end users vulnerable. Imported equipment with locked OEM software and no manuals further compounds the problem.
For this reason, Keystar focuses heavily on standard solutions that are repeatable, documented and supported. Applications such as de-greening rooms, hatcheries, ammonia valve stations and CO₂ rack controllers are delivered with defined access levels, manuals and known behaviour.
The talk concluded with a look towards the future. Many facilities still operate as‘ islands of automation’, with racks, evaporators and condensers controlled independently. The next step is system-wide integration, allowing these subsystems to communicate and optimise performance collectively.
Audience at the Cape Town TechTalk.
Artificial intelligence is already beginning to influence this space, offering early fault detection, predictive maintenance and energy optimisation. Tools such as ChatGPT are changing how technicians learn, diagnose faults and even generate control logic.
Milne stressed that while technology will continue to advance, systems must remain understandable and serviceable. Controls should support technicians, not overwhelm them, particularly when fault-finding under pressure.
The central message of the presentation was that modern controllers and PLCs are not mysterious black boxes. They are logical extensions of principles the industry has used for decades. By understanding fundamentals, embracing continuous learning and maintaining a healthy respect for standardisation, the HVAC & R sector can confidently navigate the next phase of control system evolution.
INTELLIGENT CONTROLS DRIVING MISSION-CRITICAL COOLING PERFORMANCE
As data centres become more complex and powerdense, the role of HVAC controls has shifted from simple temperature regulation to full-scale plant optimisation.
Modern chiller platforms such as the YORK YVAM and
YDAM air-cooled magnetic bearing centrifugal chillers from Johnson Controls illustrate how embedded intelligence is now central to mission-critical cooling design.
Both chillers are equipped with integrated microprocessor controls and full graphic display interfaces, enabling real-time monitoring, trending and diagnostics at unit level, says Gert Deale, sales manager at Airotech. This allows operators to:
• Monitor performance parameters continuously
• Track efficiency metrics such as NPLV
• Analyse load trends
• Detect deviations before they escalate
For data centre operators, this level of transparency is essential in environments where uptime is measured in minutes and seconds rather than hours.
Modern data centres rely on layered control strategies, with chillers forming part of a much larger ecosystem that includes:
• Building Management Systems( BMS)
• Energy Management Systems( EMS)
• Central plant optimisation platforms
• IT load monitoring systems
“ The YVAM and YDAM are fully compatible with industrystandard communication protocols such as BACnet and Modbus, enabling seamless integration into virtually any supervisory control architecture,” says Deale.
This interoperability ensures that cooling systems are not operating in isolation, but are dynamically responding to realtime IT loads and facility demands. feature
RACA Journal I June 2026 www. refrigerationandaircon. co. za 21