Integrated HVAC control architecture for efficiency and refrigerants

HVAC electrification and low-GWP refrigerants are shifting design priorities from standalone components to coordinated control of entire installations. Within this context, CAREL will present a system-oriented control and software ecosystem at MCE 2026 (Milan Rho, 23–27 March).

From unit controllers to coordinated installations
Industrial cooling applications such as food processing, cold storage, and manufacturing lines increasingly require synchronized operation across multiple units. CAREL describes an architecture where individual controller logic is embedded within plant-level management to standardize design and reduce energy use.

The STone software ecosystem provides programmable controllers, cybersecurity-oriented firmware, and secure update mechanisms intended to extend operational lifetime and reduce premature equipment replacement. A shared software platform also allows different controller models to operate under the same logic framework, while APPLICA and CONTROLLA digital tools support commissioning and lifecycle management.

By integrating unit behavior into a broader digital supply chain of plant operation, development cycles can be shortened through the reuse of control logic and reduced repetitive engineering work.

Residential heat pumps and electrified heating
For residential systems, the company will demonstrate air-to-water and water-to-water heat pump control hardware based on the STone platform. The controller combines scalable hardware with configurable application software and cybersecurity compliance.

The architecture includes PSD2 inverters — including a three-phase version with integrated active filter and a 23 A single-phase model — along with the E2V-K high-temperature electronic expansion valve, SPKT/SPKS pressure sensors, and human-machine interfaces. Together, these components manage compressor speed, refrigerant expansion, and system monitoring.

Working with natural refrigerants
To support refrigerants such as R-290, CAREL provides A3-ready, ATEX or hermetic components designed to simplify regulatory testing procedures. Safety monitoring is handled by the GLD Mini leakage detector, which uses NDIR sensing to identify gas leaks.

Partner integrations extend the control system with remote connectivity and circulating-pump management using dedicated communication protocols.

Virtual testing before physical prototypes
Development and maintenance workflows are supported by digital twin methods. The STone Virtual Loop emulates HVAC unit behavior, enabling software validation without full laboratory prototypes and improving software verification before deployment.

The same virtual environment allows updates to be evaluated across an installed base, helping maintain consistency across multiple system generations while reducing engineering cost.

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