Mitsubishi Heavy Industries KX6 VRF Series: Complete Guide for Commercial Installations

When large commercial buildings demand scalable, high-performance climate control, the Mitsubishi Heavy Industries KX6 VRF Series stands out. Designed for demanding environments such as offices, hotels, retail complexes, and educational institutions, it offers flexible design options, extended pipe runs, and exceptional zoning capabilities.

For building services engineers, M&E contractors, and commercial property managers, understanding the full capabilities of the KX6 range means better project planning, smoother commissioning, and long-term operational reliability.

Explore our commercial installation services:
https://www.climateworks.co.uk/commercial-air-conditioning

Understanding the KX6 VRF Range

The KX6 series is a modular VRF (Variable Refrigerant Flow) heat pump system using R410A refrigerant. It can be configured from small modular outdoor units to large-scale combinations capable of handling over 100 indoor units.

Mitsubishi Heavy Industries designed KX6 for ease of installation, flexible control integration, and energy-conscious operation. Its modular nature makes it equally suited to retrofits and new builds.

Full Outdoor Unit Line-Up

The KX6 outdoor units range from compact 8 HP systems to large 48 HP modules. Each unit is optimised for performance, service access, and connection flexibility.

Key outdoor models:

• FDC224KXE6M — 22.4 kW nominal capacity
• FDC280KXE6M — 28.0 kW
• FDC335KXE6M — 33.5 kW
• FDC400KXE6M — 40.0 kW
• FDC450KXE6M — 45.0 kW
• FDC500KXE6M — 50.0 kW
• FDC560KXE6M — 56.0 kW
• FDC600KXE6M — 60.0 kW

Corrosion-resistant versions (prefix FDCS) are available for coastal or rooftop exposure.

Compatible Indoor Units

The KX6 system supports a diverse range of indoor units to match architectural requirements and occupant needs.

Types available:

• 4-way cassette (360° air distribution for open-plan spaces)
• Slim ducted (for discreet ceiling integration)
• High static ducted (for long duct runs in larger zones)
• Ceiling suspended (for areas without false ceilings)
• Floor-standing (ideal for perimeter heating/cooling)
• Air handling unit (AHU) kits (for integration into existing ventilation)

System Design Flexibility

KX6 is known for its generous piping allowances and system design versatility.

• Maximum total pipe length: 1,000 m
• Maximum distance to furthest indoor unit: 160 m
• Maximum height difference (outdoor above indoor): 50 m
• Maximum height difference (indoor to indoor): 15 m

These capabilities make it suitable for tall buildings and horizontally spread facilities without compromising performance.

Installation Guidance for Contractors

Site Planning

• Position outdoor units with clear access for servicing
• Avoid recirculation of exhaust air — maintain manufacturer’s clearance distances
• Consider crane or lift access for rooftop installations

Pipework

• Follow MHI’s sizing charts for gas and liquid lines
• Maintain straight runs before branch joints
• Use approved branch kits and headers for load balancing

Electrical

• Use dedicated circuits per module
• Ensure proper earthing in compliance with UK wiring regulations
• Follow start-up procedures to prevent compressor damage

Controls and Integration

The KX6 series uses MHI’s SUPERLINK-II network for seamless communication between indoor and outdoor units.

Control options:

• Individual wired remotes
• Centralised controllers with scheduling
• BMS integration via Modbus or BACnet gateways
• Remote monitoring for off-site management

Real-World Applications

Basingstoke Office Complex

A four-storey office block with varying occupancy levels used three 28.0 kW modules to feed a mix of cassette and ducted units. Zoning allowed for weekend shutdown of upper floors, saving energy.

Guildford Hotel

The project required silent operation in guest rooms and high-capacity cooling for function halls. KX6 with slim ducted units met both needs while maintaining aesthetic standards.

Reading Retail Development

Multiple retail units with different operating hours benefited from central control, allowing independent scheduling for each tenant space.

Q&A: Installation and Selection

Q: How do I size a KX6 system for a multi-tenant office?
Calculate each tenant’s peak load, then sum totals while applying diversity factors. Use MHI’s capacity tables for precise sizing.

Q: Can I integrate KX6 with an existing BMS?
Yes, using the appropriate communication gateway. This allows centralised control alongside lighting and security systems.

Q: What’s the lead time for installation?
Typically 4–8 weeks from order to commissioning, depending on system complexity and site readiness.

Q: Do I need specialist commissioning tools?
Yes — MHI’s commissioning software and gauges are recommended for accurate refrigerant charging and diagnostics.

Q: How does KX6 handle part-load operation?
The inverter compressors adjust speed to match demand, improving seasonal performance.

Key Benefits for Commercial Clients

• Scalable from small offices to high-rise developments
• Wide choice of indoor unit styles for design flexibility
• Long pipe runs allow central plant location away from occupied areas
• Quiet operation, making it ideal for hotels and education
• Easy integration with modern building control systems

Local Expertise Matters

Working with a local specialist ensures installation meets both manufacturer standards and UK regulations. For projects in Hampshire, Berkshire, Surrey, and Oxfordshire, our team has delivered VRF solutions for offices, hospitality, and mixed-use developments.

Find out more:
https://www.climateworks.co.uk/commercial-air-conditioning

References

1. Mitsubishi Heavy Industries KX6 VRF Product Catalogue
2. MHI KX6 Technical Installation Manual
3. CIBSE Guide B2: Ventilation and Air Conditioning
4. IET Wiring Regulations (BS 7671)

Author Bio
Dr. Julian Carter is a highly experienced thermal systems expert with over 15 years in the field, holding a PhD in thermal systems. His career spans academic research, consulting, and teaching, focusing on air conditioning and refrigeration systems. Dr. Carter bridges the gap between theoretical advancements and practical applications, providing expert insights to organisations like ClimateWorks, where his guidance informs decision-making and industry best practices. Notably, he has worked on international projects with organisations such as Daikin Industries, the International Institute of Refrigeration (IIR), and the United Nations Environment Programme (UNEP). These collaborations addressed energy efficiency, sustainable refrigerants, and advanced cooling technologies. Currently a lecturer at Edinburgh University, Dr. Carter combines his expertise with a passion for educating the next generation of engineers and advancing climate control technologies.

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