1.9.0

About this release

With 1.9, we've shipped our winter 2026 release.

While release 2.0 will focus on cooling improvements for next summer, 1.9 already brings major upgrades: cooling now works just like heating, door sensors join window sensors, Z-Wave thermostats are supported, there's a new control algorithm to try, and a long list of small annoyances has been resolved.

Nothing to do after updating. Your existing setup keeps working — no reconfiguration, no migration steps. Except you relay on new options.

Thanks to everyone who reported, tested and fixed things, and special thanks to @cl445 and @wtom.

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❄️ Cooling and air conditioning

Cooling used to be the weak spot. This release rebuilt it.

• Air conditioners with a heat/cool range (a lower and an upper temperature instead of one setpoint) are handled properly now, including units that only accept both values together.
• Separate cooling temperatures for presets — Eco, Away or Comfort can mean one temperature in winter and another in summer.
• Cooling waits out the tolerance instead of switching on the moment the room is a hair too warm. Fewer short bursts.
• Changing the temperature on the AC itself or its remote is picked up correctly, instead of being mistaken for our own last command.
• If the air conditioner disappears from Home Assistant, you get a clear warning instead of silent guessing.
• Far fewer commands sent to cloud-connected air conditioners — matters for brands that rate-limit or charge per request.
• Cooling reports cooling when it is actually cooling.

We'll working on the cooling options in v2, specially on combined devices for the next summer.

🚪 Doors, on top of windows

• Door sensors can pause heating just like window sensors, with their own open and close delays — a front door counts differently from a balcony window.
• An open window or door now stops cooling too, not just heating.
• Rooms with both heating and cooling behave sensibly while a contact is open.

🧠 A new control algorithm to try

• MPC v2 — a new, more advanced calibration mode that looks ahead instead of only reacting. Pick it per thermostat in the configuration.
• Ships with room-size presets (small / medium / large room, or automatic), so there is nothing to tune by hand.
• The existing modes are untouched. Switch back any time.

📡 Z-Wave thermostats

• Z-Wave JS thermostats are supported directly, including valve control for the Eurotronic Spirit and the Aeotec ZWA021.

🔧 Better behaviour with stubborn thermostats

Many devices lie a little, round differently, or refuse commands. 1.9 handles that.

• We only send operating modes your thermostat actually offers, instead of sending something it will reject.
• Temperatures are compared in the steps your device really uses (0.5 °C, 1 °C, whole degrees), so we stop re-sending a value that is already set.
• Fahrenheit and mixed-unit setups read correctly.
• Devices with two temperature values, and devices that report their capabilities late, are detected more reliably.
• Calibration offsets a device silently ignored are sent again instead of being assumed done.
• Error messages name the setting you actually need to change.

🛠️ Valve care

• Valve exercising also runs while the thermostat is switched off — exactly when valves get stuck.
• Sleeping or unreachable thermostats are skipped instead of holding up the whole cycle.
• After the anti-sticking movement, the valve returns to the position it should be in.
• Valve commands stay inside the range and step size the device declares (noticeably better on Sonoff TRVZB).
• New service to trigger valve maintenance yourself, whenever you want.

🚀 Startup and reliability

• Missing or slow sensors during Home Assistant startup no longer produce a wave of errors — we wait, retry, and only then report a problem.
• New degraded mode notice tells you which sensor is missing and what we're doing meanwhile. Clears itself once the sensor is back.
• Removing a thermostat — or just the air conditioner from an existing configuration — works cleanly.
• Nonsense values from a sensor or from a previous restart can no longer poison the control loop.

🏠 Home Assistant integration

• Better Thermostat events show up in the Activity Log timeline, and the real hardware behind a Better Thermostat is shown on its device page.
• New diagnostic sensors for what the PID calibration is doing — useful if you like tuning.
• Better Thermostat entities work in the device-based automation editor (triggers, conditions, actions).

🌍 Setup screen, presets and translations

• Setup and options screens are fully translated, including the dropdowns and entity names that were English-only before. All eleven shipped languages brought up to date.
• Changing the target temperature now leaves the preset instead of pretending it is still active.
• Each thermostat in a group can use its own temperature step, so mixed-brand groups stop fighting each other.
• A temperature set from the app, a dashboard or an automation is no longer swallowed when it arrives at the same moment as an update from the device.

📋 Automations (blueprints) Fixes

• The weekly heating schedule blueprint saves again.
• It accepts several presence entities and several pause switches, and no longer resumes heating while another pause switch is still on.
• Older saved configurations keep working.

📖 Documentation

• New pages: presets explained, window sensors, degraded mode, and running Better Thermostat alongside a central boiler thermostat.
• The algorithm guide was rewritten to describe what each mode actually does, without promising results the project cannot back up.
• Outdated content, dead links and broken images removed.

💾 Installation Fixes

• Better Thermostat installs on Raspberry Pi and other ARM systems again — an optional maths component is no longer required.

🧪 Under the hood

Large parts of the internals were rewritten and are now covered by an automated test suite that grew several times over during this release, plus a simulation benchmark that compares the control algorithms against each other. You won't see any of it directly — you'll notice it as fewer surprises.

New Contributors

• @nizarbadriali made their first contribution in #2071
• @leow149 made their first contribution in #2105
• @proscar87 made their first contribution in #2170

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**Found something? Please open an issue: https://github.com/KartoffelToby/better_thermostat/issues

Full commit-level changelog

What's Changed

• Fix fahrenheit/celsius mishandling by @KartoffelToby in #2035
• test: validate bundled blueprints save with default inputs by @cl445 in #2047
• fix: remove dead calibration documentation links from config flow (#2040) by @cl445 in #2046
• fix: read TRV temperatures in the Home Assistant system unit by @cl445 in #2043
• fix: keep outdoor threshold working when recorder history is empty (#2038) by @cl445 in #2044
• feat: re-evaluate outdoor threshold on outdoor sensor changes by @cl445 in #2045
• chore: add diagnostic logging for TRV setpoint sync edge cases by @cl445 in #2048
• test: pin controller state-threading contract by @cl445 in #2050
• test: integration harness — real config entry against a simulated TRV by @cl445 in #2059
• docs: serve the documentation pages under their declared URLs by @cl445 in #2052
• Synchronize translations with current config flow, services and entities by @cl445 in #2062
• fix: sensor handling, store loading, and window-state hardening by @cl445 in #2054
• docs: keep README version info from going stale by @cl445 in #2064
• Disable current Preset of target temp changes by @KartoffelToby in #2067
• refactor: StateManager is the only owner of learned controller state by @cl445 in #2058
• build: manage the project with uv by @cl445 in #2027
• docs: remove stale content, fix broken doc images and 404 learn-more links by @cl445 in #2065
• refactor: typed Trv domain object replaces the real_trvs dicts by @cl445 in #2056
• mpc: seed fresh target-temp buckets from nearest sibling by @cl445 in #2002
• fix: controller state poison resistance (NaN/Inf healing at compute and restore time) by @cl445 in #2057
• build: type-check the component, strict on the calibration modules by @cl445 in #2073
• build: run pyrefly type checking in CI by @cl445 in #2075
• build: extend strict pyrefly to telemetry, retry and the Trv object by @cl445 in #2077
• docs: numpy-style docstrings for the model-fix quirk hooks by @cl445 in #2078
• chore(lint): enforce numpy docstring arg coverage and relax tests by @cl445 in #2083
• fix: allow removing the cooler entity from the configuration by @cl445 in #2091
• refactor: extract shared find_device_entity helper by @cl445 in #2101
• chore: translate remaining German comments to English by @cl445 in #2102
• fix: correct inital_tweak typo to initial_tweak by @cl445 in #2100
• chore: remove dead anti-flicker code from temperature event handler by @cl445 in #2099
• chore: trivial hygiene fixes (docstring, dead comment, boolean) by @cl445 in #2098
• fix: retry critical entities at startup before raising repair issue by @cl445 in #2093
• docs: added an algorithm selection guide to the README by @nizarbadriali in #2071
• Fix boot missing devices errors, AC Config flow removal, devel… by @KartoffelToby in #2095
• fix: compare group member setpoints in Celsius in group_all_members_off by @cl445 in #2107
• chore: drop stale open-caps mention from the reset_pid_learnings description by @cl445 in #2110
• fix: offer device automations for the Better Thermostat climate entity by @cl445 in #2112
• fix: stop the startup retry loop when the entity is removed by @cl445 in #2109
• chore: improve source comments to describe current behavior by @cl445 in #2096
• fix: recheck critical entities once the startup grace window elapses by @cl445 in #2108
• Fix dual-setpoint detection and TRV temperature handling bugs by @leow149 in #2105
• fix: harden the quirk set_temperature implementations activated by #2105 by @cl445 in #2111
• fix: only consider writable domains for the local calibration entity by @cl445 in #2113
• fix: confirm HVAC mode changes against the live TRV state by @cl445 in #2115
• fix: match setpoints with a tolerance across rounding grids by @cl445 in #2114
• feat: expose PID calibration diagnostics as sensors by @cl445 in #2097
• fix: register valve maintenance tick independently of calibration mode by @cl445 in #2127
• feat: add door sensor support with independent open/close delays by @cl445 in #2116
• test(benchmark): simulation core & scoring engine by @cl445 in #2087
• feat: link device relations and events in activity log by @KartoffelToby in #2129
• test(benchmark): restore the stacked benchmark suite stranded off develop (#2088, #2089) by @cl445 in #2132
• feat: MPC v2 calibration mode (QP + Kalman) — recovered onto develop by @cl445 in #2131
• Add cooling preset temperatures for HEAT_COOL mode by @cl445 in #2130
• fix(controlling): add send-cache and nil-guard to control_cooler() by @cl445 in #2133
• fix: render per-plant matrices for '--plant all' in benchmark runner by @cl445 in #2136
• fix: address remaining review findings from #2070 by @cl445 in #2135
• fix: don't hard-require daqp so BT installs on aarch64 (Raspberry Pi) by @cl445 in #2137
• feat: Z-Wave JS adapter + Eurotronic Spirit/Aeotec ZWA021 valve control by @cl445 in #2134
• fix: backport PID integration-step bound and cooler Fahrenheit dedup from v2 by @cl445 in #2139
• chore: update dependencies to the latest compatible versions by @cl445 in #2141
• fix(cooler): adopt only user setpoints from the cooler entity by @cl445 in #2145
• fix(cooler): write the payload a range-only cooler accepts by @cl445 in #2146
• refactor(events): share one inbound boundary for reported setpoints by @cl445 in #2147
• fix(cooler): survive an unknown cool target on a range-only cooler by @cl445 in #2154
• fix(climate): give every child its own setpoint step by @cl445 in #2155
• fix(degraded-mode): watch the door sensor and correct the repair text by @cl445 in #2156
• fix(cooler): delay the cooling switch-on by the tolerance by @cl445 in #2162
• fix(climate): bound an inbound setpoint instead of moving the other target by @cl445 in #2163
• fix(cooler): seed an unknown cool target from the cooler's own setpoint by @cl445 in #2164
• fix(cooler): decline a setpoint reported on a dead cooler state by @cl445 in #2179
• chore(helpers): read a published setpoint step through one shared rule by @cl445 in #2184
• fix(setpoint): match an inbound setpoint against the report and the clamp by @cl445 in #2190
• fix(cooler): bound re-injected targets and order the restored pair by @cl445 in #2177
• fix(mpc_v2): tie restored _initialised to the snapshot that seeded it by @cl445 in #2181
• docs: point the schedule guide at the preset actions by @cl445 in #2196
• fix: resolve a device-less thermostat model in the options flow by @cl445 in #2194
• fix: stop sending HVAC modes the TRV does not offer by @cl445 in #2198
• fix: re-assert an unconfirmed local calibration offset by @cl445 in #2201
• fix(cooler): surface an unavailable cooler through degraded mode by @cl445 in #2186
• chore(cooler): converge cooler-path wording and step tests across lines by @cl445 in #2188
• fix(calibration): make the cooling report and the idle gates agree by @cl445 in #2192
• fix: give a dual-role climate entity a single controlling channel by @cl445 in #2202
• fix: exercise TRV valves while the thermostat is off by @cl445 in #2208
• fix: agree on one default calibration mode by @cl445 in #2210
• docs: add a preset reference and a central-thermostat guide by @cl445 in #2212
• fix: keep the MQTT valve write inside the entity's declared bounds by @cl445 in #2218
• test: cover the quirk that runs for every device without one by @cl445 in #2220
• test: pin what a quirk module may define, and what it must by @cl445 in #2222
• Localize config-flow selectors and entity names by @cl445 in #2223
• fix(blueprints): stop weekly_heating_schedule from failing to save by @proscar87 in #2170
• fix(trvzb): land the requested valve position after a de-sticking bump by @cl445 in #2226

Full Changelog: 1.8.2...1.9.0