Quick Summary
The HTW-WF81-853S is designed for indoor fan coil unit systems. It controls a three-speed fan and one heating or cooling valve. The unit supports two-pipe systems with simple on/off logic. WiFi and RS485 allow both local control and building system connection.
This Smart Wifi Room Thermostat with Modbus is used in projects that need remote control and central monitoring. The page outlines key functions, control behaviour, and main parameters. It also helps with system matching and project decisions. Common questions and custom options are included for reference.
Key Features
The following points show how the Wifi Room Thermostat with Modbus’s main functions support stable and practical FCU system use.
(01) WiFi application control
WiFi allows users to adjust temperature through a mobile app. This reduces manual work on site. It improves daily use in homes and small commercial spaces.
(02) 3-speed fan and valve control
Three fan speeds allow simple airflow adjustment. One valve output controls heating or cooling water flow. This setup fits most two-pipe fan coil systems.
(03) Programmable scheduling
Weekly scheduling allows automatic temperature changes during the day. This helps reduce energy use in low demand periods. It also keeps indoor comfort stable.
(04) Multi-language interface
Multiple language options make operation easy for users. This supports use in different regions. It also reduces training time after installation.
(05) Modbus RS485 communication
Modbus allows the thermostat to connect to BMS systems. It supports central monitoring and control. This is useful for building management and energy control.
Product Design and Display
The design includes a clear screen and simple layout. It fits modern indoor spaces and is easy to install on the wall.
Technical Specifications
The table below lists key parameters used for system selection and basic operation.
| Parameter | Value |
|---|---|
| Power Supply | 95–240Vac, 50/60Hz |
| Power Consumption | WiFi 3W Max |
| Temperature Range | 5–95°C (41–203°F) |
| Floor Limit | 20–90°C (68–194°F) |
| Control Deviation | 0.5–10°C (Factory +1°C) |
| Ambient Temperature | -5–50°C |
| Protection Level | IP20 |
| Warranty | 2 Years |
Wiring Diagram
The diagram below shows typical wiring for fan coil unit control.
Model Code Guide
The table below helps explain model options and system configuration.
| Model | Application |
| 843 | Timer + 2-pipe system |
| 853S | Timer + 2-pipe + limit sensor + room card + WiFi |
| 863 | Timer + 4-pipe + limit sensor + room card + WiFi+Modbus |
| 963 | Floor heating & FCU + timer + limit sensor + room card + WiFi |
| S | RS485 Modbus |
| Example HTW-WF81-FC-xxx | If xxx=853S, it means 3 fan speed, 2-pipe system, WiFi and Modbus |
Project Fit & Customization
Wifi Room Thermostat with Modbus is not suitable for systems requiring modulating valve control. It does not support advanced PID logic. It may also not fit large central systems without protocol adjustment.
Despite this, functions can be adjusted for project needs. Modbus or other communication can be added or modified. Sensor options and control logic can also be discussed.
OEM support is available for branding and appearance. Logo printing, colour change, and labels can be customised. Packaging and interface design can also be adjusted.
Certifications and Compliance
This product meets common European standards and testing requirements.
Exhibition Moments
Our team joins international HVAC exhibitions and industry events regularly.
Frequently Asked Questions
Q1: Can this thermostat work with standard FCU systems?
It is designed for two-pipe systems with on/off valves. It fits most standard layouts. Please confirm wiring before installation.
Q2: Does it support BMS integration?
Yes, it supports Modbus RS485 communication. This allows connection to BMS systems. It enables central monitoring and control.
Q3: Can WiFi and Modbus be used together?
Yes, both can work together in one system. WiFi is used for local control. Modbus is used for building management.
Q4: Is it suitable for hotel or office use?
Wifi Room Thermostat with Modbus can be used in small to medium projects. Larger systems may need further checks. Project requirements should be confirmed.
Q5: What is the MOQ and can I get samples?
We support samples for testing. Standard MOQ is 300 units. Smaller quantities like 100 units can be discussed.
Q6: How to place an order?
Contact us to confirm details and receive a PI. Payment supports TT, PayPal, and Visa. Shipping terms include EXW, FOB, and DAP.
Q7: How long does production take?
Non-custom samples ship within 7 days. Custom orders take about 3–5 weeks. Bulk orders around 300 units need about one month.
Q8: What shipping methods are available?
Express delivery takes about 7 days. Air freight is similar. Sea freight takes about one month depending on route.
Need Support?
If you are planning a project or selecting a model, feel free to contact us. We can help review your system and suggest suitable options.
Related Thermostat Models
This section lists related thermostat models for different system types and integration needs, helping you choose a suitable option for your project.
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