Make an old heat pump smart and drive it from solar data

A Home Assistant user added a $40 eBUS adapter to a 12-year-old Vaillant geoTHERM, then had Claude Code and Claude set up the bridge, dashboards and PV-driven heat pump automations.

Done with

Claude Code

Claude

Apps touched

Home Assistant

ReportedOct 15, 2026

What they did

u/Key_Hope_36 wanted to monitor and control a 12-year-old Vaillant geoTHERM geothermal heat pump that the maker said could not be made smart. The poster bought an eBUS adapter shield (about $40), flashed its firmware and put it on the home Wi-Fi, and had an electrician wire it to the heat pump's bus port along with a Shelly energy meter. Claude Code then set up an ebusd container connected to the existing MQTT broker on the Docker-based Home Assistant install. Next, Claude connected to Home Assistant through ha-mcp checked which values showed up in MQTT and built a dashboard from them. Finally the poster had Claude write automations that steer the heat pump from the PV system's data, in restricted, failsafe ways, plus a dashboard tab that explains why each automation ran, is running or will run.

How it went

The heat pump is now monitored and controlled from Home Assistant. The poster also used Claude to understand why the heat pump behaves as it does and tweaked settings as a result. No savings figures are given.

Worth knowing

The wiring to the heat pump's bus port was done by an electrician, not the agent. Letting an agent write automations that control a heating system is why the poster kept them restricted and failsafe. A commenter noted that an existing open-source project, Thriftherm, can drive eBUS boilers without custom MQTT writes, and others reported the same setup on Saunier Duval units.

Try it yourself withTry it withClaude Code

7 parts to fill in

My [heat pump or boiler model] is connected to [an eBUS adapter] at [IP address], and I run Home Assistant on [Docker / HAOS] with MQTT at [broker address]. Set up [ebusd] to publish the heat pump's values to MQTT, then list every value that appears and what it likely means. Build a dashboard from them. Then propose automations that adjust the heat pump using [my solar or PV data], with hard limits on every setpoint and a safe fallback if data stops arriving, plus a dashboard tab that explains why each automation ran. Show me the automations and limits before enabling any of them.

Square brackets are the parts to fill in. The prompt is ours; the story is theirs.