How Does a Daikin BS Box Work: A Comprehensive Guide

The Daikin BS Box, also known as the Daikin Flex Branch Selector Box, is a compact and versatile unit designed for commercial buildings. It is engineered to provide flexibility in design, installation, maintenance, and service, making it an ideal choice for tight mechanical spaces such as ceilings. The BS Box is packed with Daikin’s state-of-the-art technology and offers various features and benefits that cater to the needs of commercial buildings.

Design Flexibility

One of the key features of the Daikin BS Box is its design flexibility. It offers versatile piping configurations of left, right, or pass-through layouts, allowing for customization based on the building’s requirements. The compact height of 9-1/2″ and 0″1 service clearance between the slab and the top of the Flex Branch Selector box make it suitable for tight ceiling spaces.

Piping Configurations

The Daikin BS Box can be configured with the following piping layouts:

  1. Left Layout: The refrigerant pipes enter and exit the BS Box from the left side, providing a compact and space-saving installation.
  2. Right Layout: The refrigerant pipes enter and exit the BS Box from the right side, offering an alternative configuration for optimal space utilization.
  3. Pass-Through Layout: The refrigerant pipes pass through the BS Box, allowing for a more streamlined and efficient installation, especially in tight spaces.

These versatile piping configurations enable the Daikin BS Box to be tailored to the specific requirements of the commercial building, ensuring an optimal and efficient system design.

Expandability and Cost Optimization

how does a daikin bs box workImage source: Daikin Air Conditioner Outdoor by Dinkun Chen

The Daikin BS Box also provides flexibility in expanding the design. It can accommodate up to 121 ports and 230Mbh1 downstream capacity by connecting multiple boxes in series. This feature allows for optimization of installed system costs by reducing REFNETs and braze joints in pass-through configuration vs non-pass-through configuration.

Connecting Multiple Boxes

The ability to connect multiple Daikin BS Boxes in series enables the system to accommodate a larger number of indoor units and increase the overall downstream capacity. This flexibility is particularly beneficial in larger commercial buildings where the cooling and heating demands may require a more extensive system.

By reducing the number of REFNETs and braze joints in the pass-through configuration, the installed system costs can be optimized, making the Daikin BS Box a cost-effective solution for commercial building owners and contractors.

Electrical and Compatibility Flexibility

The Daikin BS Box boasts simple electrical configurations with flexibility to re-position the E-box. Additionally, it allows for mixing and matching Daikin Flex Branch Selector boxes and standard branch selector boxes for ultimate design flexibility.

Electrical Configuration

The Daikin BS Box’s electrical configuration is designed for simplicity and ease of installation. The E-box, which houses the electrical components, can be repositioned to accommodate various installation requirements, providing greater flexibility in the overall system layout.


The Daikin BS Box is compatible with a wide range of Daikin products, including:

  • T-series Branch Selector Boxes
  • All M-series, P-series, and T-series VRV indoor units
  • VRV IV, VRV IV X, VRV AURORA, and VRV T-series Water-Cooled Heat recovery units

This compatibility ensures seamless integration with the full suite of Daikin VRV Controls, allowing for a comprehensive and efficient building management system.

Maintenance and Installation Simplicity

Maintenance is made easy with access to electronic expansion valve (EEV) heads and motor via side access panel. Refrigerant pipe identification labels eliminate cross piping, and simple electrical and communication wiring with connection from the front side of E-box further simplify the installation process.

Maintenance Access

The Daikin BS Box is designed with maintenance in mind. The side access panel provides easy access to the electronic expansion valve (EEV) heads and the motor, allowing for efficient servicing and troubleshooting without the need for extensive disassembly.

Installation Simplicity

The Daikin BS Box features several design elements that simplify the installation process:

  1. Refrigerant Pipe Identification: The unit comes with clear refrigerant pipe identification labels, which help eliminate the risk of cross-piping during installation.
  2. Electrical and Communication Wiring: The electrical and communication wiring connections are located on the front side of the E-box, making them easily accessible and reducing the complexity of the installation.
  3. Front-Side Connections: The front-side placement of the electrical and communication wiring connections streamlines the installation process, as technicians can access and connect the necessary components without having to navigate around the unit.

These features contribute to a more efficient and less time-consuming installation, reducing the overall cost and complexity of the project.

Safety Considerations

It is important to note that the installation of the Daikin BS Box should be performed by a licensed installer or contractor. Improper installation can result in water or refrigerant leakage, electrical shock, fire, or explosion. Using only those parts and accessories supplied or specified by Daikin is crucial for the safe and efficient operation of the unit.

Qualified Installation

The Daikin BS Box is a complex piece of equipment that requires specialized knowledge and expertise for proper installation. Attempting to install the unit without the necessary qualifications can lead to serious safety hazards, such as:

  • Water or refrigerant leakage
  • Electrical shock
  • Fire
  • Explosion

To ensure the safe and efficient operation of the Daikin BS Box, it is essential to have the unit installed by a licensed HVAC contractor or technician who is familiar with Daikin’s installation guidelines and safety protocols.

Daikin-Approved Parts and Accessories

Using only those parts and accessories supplied or specified by Daikin is crucial for the safe and efficient operation of the Daikin BS Box. Substituting non-approved components can compromise the unit’s performance and potentially create safety risks.

By adhering to Daikin’s recommendations and using only the manufacturer-approved parts and accessories, you can be confident that the Daikin BS Box will function as intended, providing reliable and safe cooling or heating for the commercial building.

In summary, the Daikin BS Box is a versatile and compact unit designed for commercial buildings. Its design flexibility, expandability, electrical and compatibility flexibility, and ease of maintenance and installation make it an excellent choice for tight mechanical spaces. However, it is essential to follow safety instructions and warnings and use a licensed installer for installation to ensure the safe and efficient operation of the unit.

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