ESPALTHERMAWeb installer

1Choose your board

2Install

Plug the board into this computer with a USB data cable, then click Install. After the installation, the installer asks for your WiFi network.

Install ESPAltherma Your browser cannot talk to USB devices. Use Chrome or Edge on a computer. The installer needs a secure page (https or localhost).

The board does not show up? Install the USB driver of your board (CP210x or CH340), and try another cable: some only charge.

Reinstalling on a board that already runs ESPAltherma keeps its settings (WiFi, MQTT, model, relays). Tick "Erase device" only to start from scratch.

Already installed? You normally don't need a file: update it from its own page, System → Firmware update → Check for an update.

3Connect it to the heat pump

Power the heat pump off first. Find the X10A connector on the main board of the indoor unit (with a Bi-zone kit, use X12A on the Bi-zone board: same pins).

X10A	Board
1 · 5V	5V / VIN (can power the board)
2 · TX	GPIO 16 (RX)
3 · RX	GPIO 17 (TX)
5 · GND	GND (always connect it, even when powered by USB)

The pins can be changed later in the web interface (Settings). ROTEX units with an 8-pin X10A: see the wiring guide.

4Finish in the web interface

1. Open http://espaltherma.local (or the address shown by the installer).
2. ESPAltherma reads your heat pump and detects its model. Confirm it.
3. Click Find my Home Assistant to connect it to your MQTT broker. The sensors appear in Home Assistant automatically.

With an ESP32-S3, ESP32-C3 or ESP32-C6, the installer may not reach the WiFi step: the board comes back as a new USB device after the installation. Enter your WiFi through the setup network described below.

No WiFi entered, or the network changed? The board opens a setup network ESPAltherma-XXXX (password espaltherma): join it and follow the page that opens. If no page opens, go to http://192.168.4.1.