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ILTO 440 econo ventilation unit (Premium panel): Decoding an ILTO 440 ventilation unit's panel bus for Home Assistant

An owner of an ILTO 440 econo ventilation unit with a 2008 Premium panel used Claude to write an ESPHome package that decodes the Swegon CASA bus and connects the unit to Home Assistant, according to the project's README. The setup runs an ESP8266 (a NodeMCU v3 was tested) with a MAX485 transceiver and a 1k/2k resistor level shifter on the panel's 4P4C cable, reading eight temperature sensors, heat recovery efficiency, fan power and status flags, and controlling fan speed 1 to 5, fireplace mode and power while verifying each command is acknowledged. The README states the integration is unofficial, was tested on one unit only, deliberately leaves installation settings such as the weekly timer, filter guard and actuators undecoded, and warns that miswiring could switch ventilation off or damage hardware; no independent confirmation was reported.

by read2 min views4 publishedNov 10, 2026
ILTO 440 econo ventilation unit (Premium panel): Decoding an ILTO 440 ventilation unit's panel bus for Home Assistant
Image: Reversedwithai (auto-discovered)

Evidence at a glance #

Based on the linked sources. The author's reported result and independent confirmation are separate checks.

  • AI involvement
  • Reported models: Claude. Tools: ESPHome, ESP8266, MAX485 RS-485. The writeup below describes the work attributed to AI.
  • Reported result
  • Works. This is the directory's source-based outcome classification.
  • Independent confirmation
  • Not reported.
  • Human work and limitations
  • The owner of the tested unit (quasd) worked with Claude, per the README. The wiring uses a 1k and 2k resistor level shifter, and the README tells readers to find the RS-485 pair with a multimeter first. Only five commits exist and none carry a trailer, so the AI evidence is the README statement and a .claude directory.

Original sources

What was done #

The README says Claude wrote the code, the protocol decoding and the documentation, working with the owner of one ILTO 440 econo. It reads eight temperature sensors and controls fan speed, fireplace mode and power.

This ESPHome package connects ILTO and Swegon CASA ventilation units with the Premium control panel to Home Assistant. An ESP8266 with a MAX485 transceiver sits on the panel's own 4P4C cable, and the unit and its panel keep working unchanged. The protocol is the Swegon CASA bus, documented in docs/protocol.md.

According to the README, it reads temperature sensors 1 to 8, heat recovery efficiency, selected fan speed, supply and extract fan power, fireplace mode, on or off state and status flags such as filter alarm, defrosting, bypass and fan failure. It controls fan speed from 1 to 5, fireplace mode and power by sending the same commands the panel sends, and checks that the unit acknowledged each one. It also keeps the unit's clock and weekday in sync with Home Assistant every night, because the weekly timer depends on them. Installation settings such as the weekly timer, filter guard and actuators are deliberately not decoded or exposed, since a wrong value could stop the unit working, and docs/protocol.md lists them as not decoded on purpose.

The README warns that the integration is unofficial, was tested on one unit only (an ILTO 440 econo with a 2008 Premium panel), and could switch ventilation off or damage hardware if wired wrongly.

Reproduce it #

Needs an ESP8266 board (a NodeMCU v3 was tested), a MAX485 module, two resistors, a 4P4C cable and a compatible ILTO or Swegon CASA unit. Include the ESPHome package from the repository and follow the wiring and polarity notes in the README.

Community #

Ask a question, share what worked, or follow the next milestone.

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