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Back to DH-Series

Heat Pump DH3

The DH3 is an all-electric driver cabin HVAC unit with reversible heat pump technology, delivering efficient heating, cooling, and windscreen demist/defrost.

Designed for buses, coaches, off-highway and commercial vehicles, it provides reliable driver comfort and safety while reducing energy consumption compared to PTC-only systems. Compact, integrated, and CAN-controlled, the DH3 is a plug-and-play solution for modern electrified and conventional platforms.

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Overview

The DH3 Heat Pump is Grayson’s latest driver cabin HVAC system, combining efficient climate control with safety-critical windscreen demist and defrost in one compact unit. Using reversible heat pump technology, it delivers efficient heating in low ambient conditions alongside consistent cooling performance.

The system is configured with 90% recirculated air and 10% fresh air, supporting efficient operation while maintaining cabin air quality. An integrated 4kW air PTC heater enhances defrost and low-temperature heating performance.

All major components, including compressor, heat exchangers, controller, and electrical systems, are packaged into a single assembly, supplied pre-charged for true plug-and-play installation. Integrated CAN J1939 communication ensures seamless control and integration across buses, coaches, off-highway vehicles and HGV platforms.

Features

Developed for driver and cabin HVAC, our heat pumps combine effective climate control with dependable year-round operation.

  • Reversible heat pump technology: Efficient heating in low ambient conditions reduces reliance on energy-intensive resistive heating.
  • Integrated 4kW air PTC heater: Supports rapid windscreen defrost and additional heating performance when required.
  • Optimised airflow configuration (90% recirc / 10% fresh air): Balances energy efficiency with cabin air quality for driver comfort and performance.
  • All-in-one packaged system: Compressor, heat exchangers, controller and electrical box integrated into a single unit for simplified specification.
  • Plug-and-play installation: Pre-charged system requiring only HV, LV and CAN connections—no on-site commissioning required.
  • Integrated CAN J1939 control: Enables seamless communication with vehicle systems and precise thermal control.
  • Compact rooftop-mounted design: Minimises installation space while maintaining performance across multiple vehicle types.
  • Designed for service exchange: Supports fast replacement and reduced downtime in fleet operations.
Technical

Every component in the system supports precise temperature regulation, improving efficiency and ensuring reliable performance in service.

  • Dimensions (L × W × H): 1184 × 264 × 544 mm
  • Weight: 70 kg
  • Heating Performance: 5 kW
  • Cooling Performance: 3 kW
  • Operating Temperature: -10°C to +35°C
  • High Voltage Range: 400 – 900 V DC
  • Low Voltage Range: 18 – 32 V DC
  • Control: CAN J1939
  • Refrigerant: R407C
Heating Capacity

5kW

Efficient cabin heating and windscreen defrost performance.
Voltage Range

400–900V DC

Compatible with a wide range of high-voltage architectures.
Cooling Capacity

3kW

Reliable driver cabin cooling in moderate and high ambient conditions.
Operating Temperature Range

-10°C to +35°C

Designed for consistent performance across typical operating environments.
Download Full Specification Sheet
Contact our team for more information

Compatible Applications

Product Benefits​

See why OEMs have selected Grayson’s DH1 Heat Pump to deliver reliable climate control for drivers in all conditions.

All-In-One Packaged System

Complete HVAC and control system integrated into one compact unit for simplified specification and installation.

Quick and Simple Installation

Delivered pre-charged for plug-and-play fitment with no commissioning required.

Flexible Configuration

Reversible heat pump and optimised airflow reduce energy consumption compared to PTC-only systems.

Low-Ambient Operation

Integrated PTC heater ensures rapid windscreen clearing for improved driver safety.

Contact Us

Looking for more information about our thermal management products, aftermarket parts and servicing, or need technical support from one of our expert engineers? Complete the form below and we will respond as soon as possible.

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Discover More About Grayson

For over four decades, Grayson Thermal Systems has been trusted worldwide to deliver dependable thermal management solutions. Our expertise ensures vehicles stay efficient and reliable, year after year.