The **FCR-AC-R** is a specific model of a Fan Coil Room Controller (often associated with brands like Regin or similar HVAC automation manufacturers). This device is designed to control heating and cooling in fan coil systems. Below is an explanation of its internal and external electronic parts and their functions. ### 1. Core Electronic Components The device operates as a microprocessor-based controller. Its internal architecture consists of the following modules: | Component | Function | | :--- | :--- | | **Microcontroller (MCU)** | The "brain" that processes sensor data and executes the control logic (P or PI control). | | **Power Supply Module** | Converts 230V AC input to low-voltage DC (typically 5V or 12V) for internal circuitry. | | **Relay Outputs** | Mechanical or solid-state switches used to control the fan speeds (Low, Medium, High). | | **Triac/Digital Outputs** | Used for modulating or On/Off control of thermal actuators (heating/cooling valves). | | **NTC Thermistor** | An internal temperature sensor used to measure ambient room temperature. | --- ### 2. Input and Output (I/O) Specifications The electronic board is populated with terminals for various field devices: #### **Inputs** * **Internal Sensor:** Built-in NTC sensor for room temperature. * **External Input:** Terminals for an external PT1000 or NTC sensor (e.g., for duct or floor sensing). * **Digital Input (DI):** Often used for "Occupancy" sensing (motion detectors) or window contacts to shut down the unit when a window is opened. #### **Outputs** * **Fan Speed Control:** Three relay outputs rated for 230V AC to toggle the fan motor windings. * **Actuator Control:** Two outputs (DO1, DO2) for heating and cooling valves. These are usually 230V AC Triacs to ensure silent operation compared to mechanical relays. --- ### 3. User Interface Electronics The front of the FCR-AC-R features a human-machine interface (HMI) consisting of: 1. **Backlit LCD Display:** Shows current temperature, setpoint, fan status, and operating mode (Heating/Cooling). 2. **Capacitive or Mechanical Buttons:** Includes a "Fan" button, "Mode" button, and "Increase/Decrease" arrows for setpoint adjustment. 3. **LED Indicators:** Sometimes used to show status for "Economy Mode" or "Alarm" conditions. --- ### 4. Technical Electrical Data | Parameter | Specification | | :--- | :--- | | **Supply Voltage** | 230 V AC ±10%, 50/60 Hz | | **Power Consumption** | < 3 VA | | **Relay Contact Rating** | 3(1) A (Fan speeds) | | **Protection Class** | IP20 (Typically for indoor wall mounting) | | **Control Algorithm** | P or PI (Proportional-Integral) | --- ### 5. Control Logic The electronic firmware allows for: * **Change-over function:** Using a sensor on the water pipe to determine if the system should be in heating or cooling mode. * **Deadband adjustment:** Prevents the system from oscillating between heating and cooling too frequently.