Runs a Honeywell Evohome house room by room from Indigo, around the clock, with no cloud involved.
Version: 1.18.1 | Author: CliveS & Claude | Needs: Indigo 2025.2 or later and my RAMSES ESP plugin
Read the full guide — setting up, how each room's temperature is decided, and what to do when something goes wrong.
This plugin lets Indigo run the heating in a house with Honeywell Evohome radiator controls. It reaches the radiators through my RAMSES ESP plugin, which talks to them over their own radio, so nothing goes through Honeywell's servers. Every five minutes it works out the right temperature for each room and sets each radiator to match.
- Heats each room to its own plan, with a temperature for every hour of the day, and guest plans for when you have visitors.
- Follows the weather, taking a degree or two off as it gets milder outside, turning radiators down above 14 degrees, and adding a little heat when snow is forecast. It reads an Ecowitt weather station if you have one, and OpenWeatherMap if not.
- Turns a radiator down when its window or door is open, and back up when it shuts.
- Stops rooms overheating, turning a radiator down before the room overshoots, and sends a Pushover message and an email if a room gets well above where it should be.
- Boosts the living areas by two degrees for one or two hours, then puts them back.
- Away and both out modes, switched by Indigo variables, hold the house at a safe, cheaper temperature.
- Shuts the heating off for summer between dates you choose, with a menu item to have it back for 24 hours.
- Looks after the En Suite — a warm room from 6am on winter mornings with the underfloor heating on, and a morning drying run on cold summer mornings to deal with wet towels.
I wrote this plugin for my own house. The twelve rooms, the window and door sensors in each one, and each room's temperature for every hour are written into the plugin, using the Indigo device numbers from my house. To use it on another house, those have to be changed in two of the plugin's files, which the guide explains. If editing a Python file is not for you, this plugin is not ready for your house yet.
It needs:
- Honeywell Evohome radiator controls, with my RAMSES ESP plugin working.
- A window or door sensor in Indigo for each window and door you want the heating to watch.
- An OpenWeatherMap API key, for the weather and the snow forecast.
- Optional: an Ecowitt weather station, the Pushover plugin and email set up in Indigo, for the outdoor temperature and the overheating alerts.
- Go to the Releases page and download
EvoHomeControl.indigoPlugin.zip - Unzip the downloaded file — you will get
EvoHomeControl.indigoPlugin - Double-click
EvoHomeControl.indigoPlugin— Indigo will install it automatically
- Put your own device and variable numbers into the plugin, and your own hour-by-hour temperatures, as the guide's Getting started page explains, then choose Plugins → EvoHome Heating Controller → Reload.
- Open Plugins → EvoHome Heating Controller → Configure, fill in your OpenWeatherMap key, your location, your Ecowitt outdoor sensor and the address for alerts, and check the summer shut-off dates — it is on from 1 June to 30 September to start with. Click Save.
- Check the Event Log has no lines about missing devices or variables, and choose Show Full Weather Log to see the outdoor temperature the plugin is using.
The full guide goes through each step, explains every setting, and covers what to do if something does not work.
v1.18.1 — An open En Suite window switches the underfloor heating off within 30 seconds, even when the radiator is being left alone, and the clocks going back no longer confuse how old a room's reading is (best with RAMSES ESP 1.17.0).
v1.18.0 — Fixes from an independent review: a room whose temperature has stopped updating is left alone (needs RAMSES ESP 1.16.0), an overheating alert that does not get through is tried again, and a missed 10am, an old snow forecast and the 1 hour setting no longer cause trouble.
v1.17.0 — The En Suite drying run now looks at the room as well as the weather: it starts when the room is below 19 degrees, or when it is cold outside, and never when the room is already warm.
v1.16.1 — On a morning too warm for the En Suite drying run, the Event Log now says so once, with the outdoor temperature.
v1.16.0 — A room somebody changes by hand, at the Evohome controller, on a valve or in the app, is left alone until its plan next changes. The summer hold now ends by itself on the day heating is due back, even if Indigo is not running. Needs RAMSES ESP 1.15.0.
v1.15.0 — Every morning the plugin checks the timetable on the Evohome controller against its own plans, and tells you if a room differs. Needs RAMSES ESP 1.13.0.
v1.14.0 — Timed boosts and Force Heating On last the right time across a clock change. Away mode no longer adds up with Boost or Both out, and an open window closes the radiator while away. The Boost variable is no longer cancelled by overheat checking. Also a guest-plan fix, and old settings removed.
v1.13.0 — If Indigo stops, the house goes back to the Evohome timetable: each radiator's temperature is sent for two hours at a time and renewed about hourly, instead of being held indefinitely. The summer hold stays permanent. Needs RAMSES ESP 1.12.0.
v1.12.0 — Fixes made before the heating came back on. Last spring's overheating record is cleared rather than reloaded, a stopped Ecowitt station or a quiet radiator zone is noticed instead of trusted, and the En Suite underfloor heating is no longer left on by away mode, an open window or the plugin being stopped at 10am.
v1.11.0 — A boost no longer heats a room with a window or outside door open. The room keeps its open-window setting, so the Dining Room stays at 16 degrees with the garden door open instead of going to 18, and picks the boost up again once everything is shut.
v1.10.0 — The Dining Room now really does stay at 16 degrees with a garden window or door open, instead of dropping to 8. Overheating alerts go to the Pushover user key you set, away mode stops the En Suite drying run, and the drying run no longer starts on a morning it cannot tell is cold.
v1.9.2 — The En Suite drying run only starts when it is colder outside than a limit you choose, 12 degrees to start with, or No limit. A morning that only turns cold at 7am still gets a run, and Show En Suite Drying Run Status shows the limit against the temperature now.
Every version is listed in the version history.
Vibed into existence by CliveS, who knew what he wanted, argued until he got it, and tested it on a real house. Typed at inhuman speed by Claude (Anthropic), who mostly did as it was told.
© 2026 CliveS · MIT licence — copy it, fork it, bend it, break it, fix it, ship it. If it breaks, you get to keep both pieces.