Build a Smarter Radiator Fan Controller / Heat booster with This ESP32-C3 Design

Smart Radiator Fan Controller with ESP32-C3

Unlock the full thermal potential of your heating system with this intelligent, automated fan controller PCB. Designed for efficiency and reliability, this circuit actively manages heat dissipation to improve the performance of any radiator.

Traditional radiators often struggle to distribute heat effectively into a room, relying solely on passive convection. This design transforms any standard radiator into a high-efficiency convector unit by adding a grid of 12V fans that activate precisely when needed. By actively moving air across the radiator fins, this system significantly increases the heat transfer rate, warming your space faster and more efficiently.

At the core of this controller is the powerful and WiFi-enabled ESP32-C3 SuperMini Pro microcontroller. Paired with a high-precision AHT20 temperature sensor, the system constantly monitors the radiator's surface temperature. When the temperature exceeds a preset threshold of 45°C, the controller automatically powers a bank of 4-6 fans, directing the accumulated heat into the room. As the radiator cools, the fans are deactivated, ensuring silent operation and minimal power consumption.

Technical Design Highlights:

This schematic is engineered for robust performance, electrical safety, and flexible control, using a carefully selected set of components:

Intelligent Control: An ESP32-C3 SuperMini Pro serves as the brain, offering low-power operation and Wi-Fi connectivity for potential integration with smart home systems like ESPHome and Home Assistant.
Precision Sensing: An AHT20 I²C sensor provides accurate, real-time temperature data, forming the basis for reliable automation.
Isolated High-Current Switching: Fan power is controlled by a 2N7002/AO3400A N-Channel MOSFET, capable of handling the combined current of multiple fans with ease. To protect the sensitive microcontroller, the MOSFET is triggered via a PC817C optocoupler, creating complete electrical isolation between the 3.3V logic and the noisy 12V fan power circuit.
Variable Speed & RPM Monitoring: The design includes a dedicated PWM output (GPIO2), allowing for precise fan speed control (800-3000 RPM). A tachometer input (GPIO1) enables the system to read the actual fan speed for closed-loop control or performance monitoring.
Stable Power Delivery: A compact and efficient DC-DC step-down converter (e.g., MP1584EN-based) reliably transforms the 12V input to a clean 3.3V for the ESP32 and sensor. The circuit is further stabilized with dedicated decoupling capacitors (10µF and 100nF) to filter out voltage fluctuations and ensure flawless microcontroller operation.

Advantages of This Design:

Enhanced Thermal Efficiency: Actively dissipates heat, warming rooms faster.
Fully Automated: "Set-and-forget" operation based on precise temperature triggers.
Circuit Protection: Opto-isolation safeguards the microcontroller from the high-power fan circuit.
Flexible & Smart: Offers both simple on/off control and advanced PWM speed adjustment, with potential for full smart home integration.
Reliable & Robust: Built with industry-standard components designed for long-term stability.

This schematic provides a complete, tested, and reliable foundation for building a powerful and efficient upgrade for any hydronic heating system.