Quick Summary
HTW-WF01-FC-4KN Modbus Thermostats designed for 4-pipe fan coil units in commercial and residential buildings. It regulates a multi-speed fan and two independent heating and cooling valves according to sensed room temperature.
The thermostat includes programmable schedules, keycard-based energy-saving input, and RS485 Modbus communication. Powered by 110VAC or 220VAC, it is intended for indoor wall-mounted installation.
This page explains how Modbus Thermostats coordinate fan and valve operations, maintain temperature accuracy, integrate with building systems, and allow project-specific customization.

Key Functional Highlights
-
Independent Heating and Cooling Valve Control
Modbus Thermostats manage separate heating and cooling valves in 4-pipe FCU systems. This prevents simultaneous heating/cooling conflicts and ensures precise seasonal operation across multiple rooms. -
Multi-Speed Fan Regulation
Supports 3-speed fan output with stable relay switching. Clear separation of fan and valve circuits reduces wiring errors, enhances reliability, and allows predictable response for maintenance checks. -
Programmable Weekly Schedules
Modbus Thermostats supports flexible weekly programs, enabling temperature profiles for occupied and unoccupied periods. Energy efficiency is maximized without sacrificing comfort, ideal for hotels and offices. -
Keycard Energy-Saving Input
Optional keycard interface automatically shifts the system to energy-saving mode when rooms are unoccupied. It ensures consistent operation while reducing unnecessary energy consumption in hospitality environments. -
RS485 Modbus Communication
Enables centralized monitoring, parameter adjustments, and coordination with BMS. Multiple Modbus Thermostats can operate together, providing uniform performance and simplified project-wide control. -
Stable Relay Design and Electrical Safety
Fan relay supports 5A (3A inductive), valve relay 3A (1A inductive). The design minimizes risk of overload, allows straightforward wiring, and improves long-term operational reliability under varying load conditions.
Details
Specifications
| Item | Specification |
|---|---|
| Power Supply | 110(+/-10%)VAC or 220(+10%,-15%)VAC |
| Frequency | 50/60Hz |
| Control Type | 4-pipe fan coil system |
| Accuracy | ±1°C at 21°C |
| Fan Relay Load | 5A (3A inductive) |
| Valve Relay Load | 3A (1A inductive) |
| Setpoint Range | 5–35°C |
| Installation | 86×86 mm box or US 2×4 in box |
Display

Wiring

Project Fit & Customization
Modbus Thermostats are suitable exclusively for 4-pipe fan coil unit installations. It should not be used in 2-pipe systems, standalone setups without Modbus integration, outdoor locations, or areas requiring protection above IP20. Temperature accuracy and valve control logic are optimized for indoor environments, ensuring stable operation under typical commercial, residential, and hospitality conditions.
OEM customization options include logo printing, housing color, and packaging modifications. ODM-level adjustments, such as schedule presets, Modbus parameter alignment, or special relay logic, can be discussed based on project requirements. All customizations are subject to engineering verification to guarantee system compatibility and performance.
Certifications and Compliance
This thermostat complies with European market requirements and is supported by certifications such as CE, RoHS, LVD test reports, EMC test reports, etc.

Exhibition Moments
Our team regularly participates in international HVAC exhibitions such as Febrava in Brazil, The Big 5 in Dubai, and ISK-SODEX in Turkey, etc.

Frequently Asked Questions
Q1: Can this thermostat be used in a 2-pipe system?
No. This model is designed for 4-pipe systems with independent heating and cooling valves.
Q2: Does it integrate with building management systems?
Yes. RS485 Modbus communication allows centralized monitoring and management across multiple thermostats.
Q3: Are samples available and what is the MOQ?
Samples are supported. Standard MOQ is 300 units, and smaller trial orders can be discussed.
Q4: Is the keycard input required for operation?
No. The thermostat works normally without connecting the keycard. It only activates energy-saving mode when used.
Need Support
If you are selecting a model or planning a project, please contact us. We can help choose the right thermostat.
Related Thermostat Models
More product details, please click directly:
For 4-pipe FCU projects, Modbus Thermostats should be selected by system structure, valve output, fan relay load, Modbus communication needs, and keycard energy-saving requirements. The HTW-WF01-FC-4KN is suitable for projects that need independent heating and cooling valve control, 3-speed fan operation, programmable scheduling, RS485 Modbus integration, and optional hotel keycard input. For OEM buyers, contractors, and system integrators, confirming wiring, power supply, communication settings, BMS requirements, and project quantity before ordering will help reduce commissioning risks and improve long-term HVAC control reliability.





