REAL Air Purifier HEPA & Activated Carbon WITH HA

This air purifier has been designed around a key constraint: maintaining a high airflow rate despite the use of highly restrictive filters (HEPA + activated carbon).

The system is based on a symmetrical dual-intake architecture. Each side integrates a complete filtration chain composed of a protective grille, a pre-filter, a HEPA filter, and an activated carbon filter. This configuration significantly increases the effective filtration surface while balancing airflow, resulting in improved overall efficiency and extended filter lifespan.

The airflow is driven by four high static pressure 140mm PC fans, arranged in two branches of two fans mounted in series. This design choice increases the available pressure to push air through dense filter media while maintaining usable airflow. Unlike a typical parallel configuration, this setup is specifically optimized for high resistance systems.

The fans used in this build are standard 12V models (0.35A max), similar to these:
https://amzn.eu/d/0a4a1m5m

The system remains energy efficient ⚡, making it suitable for continuous operation.

To further reduce noise, the entire unit is mounted on two large TPU feet designed to absorb vibrations generated by the fans 🔇. This significantly minimizes structure-borne noise and improves overall acoustic comfort during operation.

Particular attention has been paid to air sealing. In addition to the already tight mechanical design, I personally added mastic seals at critical junctions to ensure near-perfect airtightness and prevent any bypass of unfiltered air 🛡️.

The filters used in this design are standard and easily available. You can find compatible HEPA + activated carbon filters here:
https://amzn.eu/d/0deVAqb1

From a mechanical standpoint, the assembly is based on a consistent M4 hardware ecosystem:

The fan enclosure is secured using 8 M4 countersunk screws (70 mm) combined with 8 M4 square nuts, ensuring proper compression and airtight sealing of the airflow section:
https://amzn.eu/d/03XuKp4n
https://amzn.eu/d/07umiTqa

The TPU feet are mounted using 4 M4 screws (12 mm) and 4 M4 square nuts, providing a stable and vibration-isolated base:
https://amzn.eu/d/07umiTqa

The rest of the structure is assembled using 26 M4 screws (35 mm) combined with 26 M4 threaded inserts, ensuring strong, durable, and repeatable fastening within the 3D printed parts:
https://amzn.eu/d/08OvjnVD

Control is handled by an ESP32 running ESPHome, allowing native integration with Home Assistant 🧠. This enables dynamic airflow control, automation based on air quality, and remote operation.

Finally, the structure has been designed to be robust, modular, and fully compatible with 3D printing, with integrated mechanical protections and easy access to each filtration stage.

This design aims to balance performance, energy efficiency, and accessibility, while remaining fully customizable for applications ranging from office use to workshops or 3D printing environments.