The Versatile D Series fan coil thermostat is intended for HVAC terminal units where control requirements vary by valve type, fan motor, power supply, or building automation architecture. Rather than being limited to a single FCU configuration, the series provides different model combinations for common terminal-control applications.
Typical applications include:
2-pipe FCU systems for heating or cooling applications in commercial and residential buildings
4-pipe FCU systems requiring independent heating and cooling valve control
AC 3-speed fan coil units using conventional fan-speed switching
BLDC fan coil units requiring dedicated brushless DC motor control
0–10V modulating valve applications where proportional valve positioning is required
Floating valve control systems using open/close actuator positioning
24V HVAC terminal units, including low-voltage electrical heating applications
Building automation projects using RS-485 communication and Modbus-RTU on applicable HL8xxx models
The series can therefore be used across different terminal-unit designs rather than being restricted to one standard FCU wiring configuration. For broader HVAC control requirements, see Hailin Controls' thermostat product range and HVAC control products.
For building-level applications, the Versatile D Series can be incorporated into commercial building and complex projects, smart hospital solutions, hotel building automation projects, and smart laboratory solutions.
Installation Diagram
Installation requirements depend on the specific Versatile D Series model and the terminal equipment being controlled.
The thermostat is designed for 86 × 86 mm wall mounting, with a 60 mm mounting-hole spacing for common wall-box installations. Before wiring, the selected model should be matched with the FCU configuration, valve actuator, fan motor type, and power supply specified for the project.
For standard hydronic heating and cooling models, the terminal arrangement supports one 2.5 mm² wire or two 1.5 mm² wires. Electrical heating versions use a 4 mm² connection and are designed for higher resistive loads, with applicable models rated up to 16A.
Because the terminal assignment is model-specific, the wiring diagram supplied with the selected thermostat model should be followed during installation rather than applying one common wiring scheme to the entire series.
Why Choose Hailin Controls
The Versatile D Series is designed around application flexibility rather than a single fixed thermostat configuration. This makes it suitable for projects where FCU specifications can differ between rooms, floors, or buildings.
Key advantages include:
Multiple control configurations covering conventional fan-speed switching, proportional valve control, floating valve operation, and selected BLDC fan applications
Different power options, including standard AC-powered models and applicable 24V variants
2-pipe and 4-pipe compatibility across the product family, helping engineers select a model according to the actual FCU arrangement
Optional RS-485 communication on applicable HL8xxx models for integration with building automation systems
Local programmable operation for temperature and schedule management without requiring a centralized controller for standalone applications
86 × 86 mm installation format for straightforward replacement or installation in compatible wall boxes
Product documentation and technical assistance from Hailin Controls, with additional information available through the company's technical services
FAQ
What type of FCU can the Versatile D Series control?
The series includes models for different fan coil configurations, including 2-pipe and 4-pipe FCUs. Depending on the model, it can also accommodate AC 3-speed fans, BLDC fan motors, modulating valves, or floating valves.
How should I select a Versatile D Series model?
Model selection should be based on the FCU piping arrangement, valve type, fan motor, operating voltage, and communication requirements. For example, a conventional 3-speed AC fan and a BLDC fan require different control configurations, while an RS-485 project requires a compatible network model.
Are all Versatile D Series models compatible with Modbus-RTU?
No. Modbus-RTU communication is available on applicable HL8xxx models with RS-485. Standard standalone models do not provide the same network communication function.
What is the difference between a 2-pipe and 4-pipe FCU?
A 2-pipe FCU uses a common water circuit for either heating or cooling, depending on the system configuration. A 4-pipe FCU has separate heating and cooling circuits, allowing the thermostat to control the two functions independently.
Can the thermostat be used for electrical heating?
Applicable 24V and electrical-heating variants are available within the series. These models use a different wiring arrangement and load rating from the standard hydronic FCU versions.
Where can I find installation information?
Installation and wiring information should be checked against the manual for the specific model because terminal assignments differ between FCU, valve, fan, and electrical-heating configurations. Hailin Controls also provides technical services and product support for project requirements.
