Grayson Debuts Complete Thermal Management Systems at Busworld Europe 2025

Grayson Thermal Systems is showcasing its latest innovations in high-voltage, integrated thermal management for electrified buses at Busworld Europe 2025 (4–9 October, Brussels Expo, Hall 5, Stand 532)

The British heating and cooling specialist is presenting its new Complete Thermal Management Systems (CTMS) range – a major step forward in multi-loop, refrigerant-based solutions designed to manage the combined demands of passenger and driver HVAC, batteries, and power electronics in next-generation buses.

The range includes the rooftop-mounted RM-series and compact chassis-mounted CM-series, both engineered to optimise efficiency and performance while reducing system complexity for OEMs.

The centrepiece of Grayson’s Busworld display is the CTMS RM-series, a rooftop-mounted, high-voltage system designed for next-generation electric city buses and coaches. The flagship RM2-800V delivers up to 33kW of air conditioning at 40°C ambient, with reversible heat pump technology, waste-heat recovery, active and passive battery cooling, and optional battery heating. Compatible with global markets (LHD and RHD) and operating up to 900V DC, the RM-series offers OEMs a single, scalable platform to handle all vehicle thermal demands for drivers, passengers and powertrain.

“The RM-series represents a leap forward in bus thermal management,” said Matthew Hateley, Head of Sales and Marketing at Grayson Thermal Systems. “For OEMs, it means a single, scalable solution that integrates HVAC, battery, and powertrain cooling into one intelligent platform. With our integrated automatic temperature control platform, this not only improves efficiency and vehicle performance but simplifies design and reduces the need for multiple thermal variations across fleets.”

Hateley continued: “What excites us is the impact this has for the next generation of electric buses. With demand for higher DC voltage systems and growing demands for efficiency, comfort, and range, OEMs need solutions that do more with less. The RM-series, which offers up to 40kW at 40°C of cooling capacity in the range, embodies that vision – advanced, reliable, and engineered to deliver optimal performance in real-world conditions.”

Alongside the RM-series, Grayson is also displaying the first model from its compact CTMS CM-series. The CM1-800V is a chassis-mounted, fully integrated system delivering battery, power electronics, and driver cabin thermal management. Offering up to 10kW of cooling at 40°C ambient in a space-efficient package, it is designed for applications where compactness and flexibility are critical.

Both series are powered by Grayson’s Intelligent Thermal Controller and proprietary CAN J1939-based software, providing OEMs with automatic temperature control, set-point adaptability, diagnostics support and simplified integration.

Also debuting at Busworld is Grayson’s new CM1-800V DC – the first in its series of chassis-mounted complete thermal management systems – and the RM2-800V DC, part of its new rooftop-mounted CTMS range.

In addition to its CTMS range, Grayson is unveiling several new high-voltage components, including two models (EW3 and EW4) for its new PTC electric water heaters. The auxiliary heaters deliver variable, self-regulating, CAN-controlled heating modules for 800V circuits, engineered for larger buses and colder climates. The company is also demonstrating its PE1-800V cooler, a new one-fan cooling module for power electronics and traction motors incorporating tube-and-fin technology and high-voltage 800V DC fan as standard, with variable fan speed control through Grayson’s CAN-enabled controller.

“Busworld is about looking ahead to what’s next for the industry,” added Hateley. “Grayson is ready to support OEMs in Europe and across the globe with total thermal management solutions, from fully integrated CTMS platforms to standalone components that can be combined for maximum flexibility. We look forward to showing visitors how our technology can help them achieve efficiency, reliability, and performance in their next projects.”

Throughout Busworld, Grayson is also displaying selected products from its established portfolio, including electric water pumps, HMI control panels, and advanced temperature and CO2 monitoring sensors, reinforcing its position as a global partner for OEMs seeking both complete systems and critical components.