Quick Summary
The HTW-WF03-FC-4N Modbus Thermostat is designed for 4-pipe fan coil systems with separate heating and cooling circuits. It controls a 3-speed fan and two motorised valves for independent heat and cool operation. With RS485 communication, the Modbus Thermostat enables integration into BMS systems for central monitoring and control.
This page explains how the Modbus Thermostat works in 4-pipe FCU systems and how it supports building-level control strategies. It also includes wiring reference, technical parameters, and model guidance, followed by project considerations, customisation options, and practical questions with clear answers.
Key Features
(This section explains the core control functions and their practical value.)
(01) Modbus communication for system integration
The Modbus Thermostat supports RS485 communication, allowing connection to building management systems. This helps centralise control, monitor performance, and improve system coordination across multiple zones.
(02) 4-pipe system compatibility
The Modbus Thermostat is designed for systems with independent heating and cooling pipes. This allows precise temperature control without seasonal switching and supports flexible operation. If you need the same model for 2-pipe system with Modbus function, please refer to this link: HTW-WF03-2N.
(03) Dual valve control
The Modbus Thermostat controls two on/off motorised valves for heating and cooling. This ensures stable performance and accurate control in complex FCU system layouts.
(04) 3-speed fan control
Three fan speeds provide flexible airflow adjustment. This helps maintain indoor comfort while balancing noise level and energy consumption in different room conditions.
Product Design and Display
(This section shows the product’s dimensions and the interface layout.)
Technical Specifications
(This section lists the key parameters for reference and project confirmation.)
| Power Supply | 100~250VAC |
| Frequency | 50/60Hz |
| Fan Relay Load | 5A (3A inductive) |
| Valve Relay Load | 3A (1A inductive) |
| Accuracy | ±0.5°C or ±1°F |
| Sensor | NTC3950, 10K |
| Setpoint Range | 5~35°C |
| Installation | EU or standard electric box |
Wiring Diagram
(This section provides the wiring reference diagram for correct installation.)
Model Code Guide
(This section explains what configuration the model code refers to.)
| Fan coil series | xx stands for |
| EC | EC fan |
| 2/4 | 2 for 2-pipe on/off; 4 for 4-pipe on/off system |
| M | Modulating valve control |
| W | Wi-Fi |
| N/B | N for Modbus; B for BACnet |
| K/E | K for Keycard; E for External sensor |
| Example | HTW-WF03-FC-xx: if xx = 4N, it stands for a 4-pipe system with on/off valve control and Modbus communication. Most sub-models are ready-made. Kindly contact us to confirm availability. |
Project Fit & Customization
(This section explains where the product can be used, its limits, and OEM/ODM options.)
The Modbus Thermostat is suitable for FCU systems requiring central monitoring and control with separate heating and cooling circuits. It is not suitable for projects needing BACnet protocol or 0-10V modulating valve control.
Despite these limits mentioned above, ODM customisation can be discussed based on project needs. Communication protocols or control logic may be adjusted depending on system requirements.
OEM customisation is also supported. Options include logo printing, colour customisation, and label design. These help align the thermostat with project branding and installation standards.
Certificates and Compliance
Frequently Asked Questions
Q1. Can this thermostat connect to a BMS?
Yes, it supports RS485 Modbus communication for integration with building management systems.
Q2. Is it suitable for 2-pipe systems?
No, this model is designed for 4-pipe systems with independent heating and cooling control.
Q3. What type of valve control is used?
It uses on/off control for motorised valves, suitable for standard FCU system configurations.
Q4. Do you support samples and what is the MOQ?
Yes, samples are available. MOQ is usually 300 units, but smaller quantities can be discussed.
Q5. How can we place an order?
Please contact us to confirm requirements. We will issue a PI. Payment supports TT, PayPal, Visa. Terms include EXW, FOB, DAP.
Q6. How will the goods be shipped?
Courier delivery takes about 7 days. Air freight is similar. Sea shipping usually takes over one month depending on destination.
Related Thermostat Models
For 2-pipe Modbus versions, you may refer to /products/htw-wf03-fc-2n, or contact us for project selection support. You can refer to below links:
