The RM2 CTMS offers a balanced combination of high thermal management performance, energy efficiency, and intelligent control.

Engineered for modern electric city buses and coaches, it unites passenger and driver HVAC, battery thermal management, and powertrain cooling in a single, rooftop-mounted unit.

Its reversible heat pump ensures efficient heating and air conditioning, supported by active and passive battery cooling, standard waste-heat recovery, and an optional PTC heater for low-ambient conditions.

Grayson’s proprietary automatic thermal controller and CAN J1939-based software deliver precise temperature regulation and system integration with external components.

Equipped with Grayson’s Automatic Intelligent Thermal Controller and proprietary CAN J1939-based thermal control logic software, the RM2 provides precise, efficient control of all thermal loads.

Compatible with high-voltage systems up to 900V DC, the system combines modular flexibility, lightweight construction, and low power draw – helping OEMs meet demanding efficiency, performance, and comfort targets across global markets.

The CTMS RM2 is also backed by Grayson’s full lifecycle services, including integration support, field service, and aftermarket parts supply.

These key features enhance functionality, durability, and compatibility with vehicle systems.

• Reversible heat pump: Provides both heating and air conditioning for driver and passenger comfort.
• Battery Thermal Management: Active cooling, passive cooling, and heating functions to protect cell life.
• Optional Coolant Loops: Enable power electronics and traction motor cooling for total system control.
• Waste Heat Recovery: Improve energy efficiency and reduces overall power consumption.
• Low-GWP refrigerant (R-454C): Reduce environmental impact while maintaining performance.
• Passive Cooling Functionality and Waste-Heat Utilisation: Optimise energy use and extend range.
• Grayson Intelligent Thermal Controller: Developed and validated by Grayson for precision regulation.
• CAN J1939 Communication: Seamless integration with pumps, heaters, and sensors.
• Dynamic Control Software: Continuously adjusts operation to match vehicle thermal demands.
• Suitable for 8 m – 24 m Bus Lengths: Compatible with LHD and RHD configurations.
• High-Voltage Capable: Up to 900V DC, meeting the needs of next-generation electric platforms.

The technical design supports consistent operation across varying loads and operating conditions.

• Nominal Cooling Capacity: 28kW @ 40°C ambient
• Maximum Cooling Capacity: 33kW @ 40°C ambient
• Nominal Heating Capacity (Heat Pump): 25kW @ 0°C ambient
• Maximum Heating Capacity (Heat Pump): 33kW
• Operating Temperature: -20°C to +45°C
• High Voltage Range: 540–900V DC (Nominal 800V)
• Low Voltage Range: 18–32V DC (Nominal 28V)
• Refrigerant: R454C
• Dimensions (L × W × H): 2450 × 2000 × 365 mm
• Weight: 240kg
• Communication: CAN protocol: J1939
• Ingress protection: IP67 (controller box)