Intelligent FCU & FAHU Control with BA190 Edge I/O Module

1. Solution Overview

This solution utilizes the Beilai Technology BA190 BACnet/IP Edge I/O module as a field controller, providing a standardized, intelligent, and highly integrated local control solution for Fan Coil Units (FCUs) and Fresh Air Handling Units (FAHUs) in buildings. By deploying control logic at the network edge, it achieves precise regulation and efficient management of HVAC terminal units, thereby enhancing indoor comfort, significantly reducing energy consumption, and simplifying operational maintenance.

2. System Architecture & Working Principle

• Perception Layer: Temperature and humidity sensors, differential pressure switches, freeze-stat switches, manual control switches, etc.
• Control Core: BA190 main module + compatible Y-series I/O expansion modules.
• Execution Layer: Damper actuators, water valve actuators, fan motor contactors/VFDs.
• Management Layer: Seamless integration with the upper-level Building Management System via the BACnet/IP protocol.

Workflow:

1. The BA190 collects analog and digital signals from sensors in real-time.
2. The built-in edge computing engine executes preset control logic and PID algorithms.
3. The BA190 drives the output modules to control actuator movements, regulating air volume, water flow, etc.
4. All operational statuses, alarm information, and energy data are uploaded to the monitoring center via BACnet/IP.

Part 1: Fan Coil Unit Control

Control Objects & Goals

Achieve independent, precise temperature control for individual indoor spaces and support multiple operating modes.

BA190 I/O Configuration Selection

For FCU control, the recommended input/output module selections are as follows:

For Digital Inputs, used for collecting 3-speed switch status, remote start/stop signals, and filter clogging alarm signals, the Y13 module is recommended. A single Y13 module can cover the digital input needs of multiple FCUs.

For Analog Inputs, used for connecting room temperature and humidity sensors, the Y31 module or the Y33 module is recommended. Typically, one analog input channel is required per FCU.

For Digital Outputs, used for controlling the fan's high, medium, and low speeds, the Y24 module is recommended. One Y24 module can handle the speed control for multiple FCUs.

For Analog Outputs, used for continuously modulating 2-way or 3-way water valve opening, the Y41 module or the Y43 module is recommended. Typically, one analog output channel is required per FCU that needs precise temperature control.

Typical Control Logic:

• Auto Mode: Based on the deviation between the room temperature and the setpoint, a PID calculation outputs a signal via the Analog Output module to control the water valve opening, maintaining a constant temperature.
• Fan Speed Control: The fan speed is switched via the Digital Output module based on user selection or an automatic program.
• Alarm: A filter clogging alarm detected by the Digital Input module triggers an alarm uploaded to the BMS.

Part 2: Fresh Air Handling Unit Control

Control Objects & Goals

Optimize the fresh air ratio, ensure supply air parameters, prevent coil freezing, and achieve efficient and safe operation.

BA190 I/O Configuration Selection

For FAHU control, the input/output module configuration is as follows:

For Analog Inputs, used for collecting signals such as supply air temperature/humidity, return air temperature/humidity, outdoor air temperature/humidity, and cold/hot water valve position feedback, the Y31 module or the Y33 module is recommended. Due to the number of monitoring points, multiple analog input modules are usually required.

For Digital Inputs, used for receiving filter differential pressure alarms, freeze-stat alarms, fan run status, and fault status, the Y13 module is recommended. One Y13 module is typically sufficient for all digital alarm and status monitoring needs.

For Analog Outputs, used for modulating cold/hot water valve opening and controlling fresh air/return air damper opening, the Y41 module is recommended. Typically, one such module is needed for the actuator control of a single FAHU.

For Digital Outputs, used for fan start/stop control and alarm indication, the Y24 module is recommended. One Y24 module is usually sufficient for these switching control tasks.

Typical Control Logic:

• Supply Air Temperature Control: The supply air temperature is collected and compared with the setpoint. A PID calculation results in an Analog Output signal modulating the cold/hot water valve opening.
• Damper Control: Based on the enthalpy comparison between outdoor air and return air, the Analog Output module controls the damper actuators to achieve the optimal fresh air ratio, making full use of free cooling potential.
• Interlocked Start/Stop: The water valves and dampers enter automatic regulation mode only after the fan has started.
• Freeze Protection: When a freeze-stat alarm is triggered, the Digital Output module immediately closes the dampers, and the Analog Output module fully opens the hot water valve to protect the coil.

4. Core Advantages of Using the BA190

1. Integrated Solution, Reduced Costs
2. Edge Intelligence, Enhanced Reliability & Energy Efficiency
3. Flexible Configuration & Convenient Maintenance
4. Industrial-Grade Quality, Harsh Environment Suitability
5. Remote Maintenance & Data Analysis

5. Summary

The Beilai Technology BA190 BACnet/IP Edge I/O module provides a highly flexible, cost-effective, and future-oriented solution for controlling FCUs and FAHUs. It centralizes distributed control, adds intelligence to simple switching operations, and achieves efficient integration with building management systems through open standard protocols. This solution is not only an effective way to enhance building comfort and energy efficiency but also an ideal choice for building a modern, intelligent building operation and maintenance system.

More Details https://bliiot.com/collections/edge-io-modules