Bosch
Bosch Smart Home Room Thermostat II 230V
- Zigbee
Verified September 2026
A mains-powered wall thermostat (model BTH-RM230Z) that pairs straight into Zigbee2MQTT — the built-in relay is exposed as a switch, a tidy wired replacement for an underfloor-heating or electric-heating stat without any Bosch controller. It's an electrician job: needs 230V at the backbox and a 35mm-deep flush-mount box, and the relay only switches up to 3A resistive (690W) or 1A inductive, so check it covers your UFH actuator or heating load before buying. Against the Heatmiser neoStat Pro on this site, it's the cheaper single-zone option with no hub — but Heatmiser's screed floor-limit logic and 32-zone neoHub scale further for whole-house wet UFH.
In Home Assistant
| Control | Type | What it does |
|---|---|---|
| Climate | Climate | Core climate entity — off/heat modes, live room temperature, and target setpoint. |
| Relay state | Binary sensor | Read-only exposure of the physical relay contact position, separate from the climate entity's own state. |
| Operating mode | Select | Schedule/manual/pause — manual severs the relay from the thermostat's internal control loop so automations can switch it directly. |
| Heater type | Select | Underfloor heating / radiator / central heating / manual — tells the firmware which load it's driving, affecting setpoint and overheat-protection behaviour. |
| Floor probe | Sensor | Reading from an optional external floor/cable probe, independent of the onboard air-temperature sensor, usable for slab over-temperature cutoffs on UFH runs. |
The operating mode exposes a manual-control setting that decouples the relay entirely from the thermostat's own setpoint logic, so an automation can drive heating on/off directly without fighting the built-in schedule. A separate heater-type setting changes how the firmware interprets setpoint and overheat protection, and early converter builds had the enum values swapped on some firmware revisions, so it's worth confirming the mode actually applied rather than trusting the dropdown label. For UFH installs there's also an external floor-probe reading distinct from the onboard air-temperature sensor, which can gate a slab-protection automation independently of the room reading. Note Bosch's Zigbee stack requires the install code printed on the device to join — a bare permit-join in Zigbee2MQTT won't pair it like a standard third-party Zigbee device.
Specs
- model
- BTH-RM230Z
- power
- 230V AC mains, flush-mounted (wired)
- relay
- Built-in, exposed as switch in Zigbee2MQTT
- display
- Digital display, shows room temperature by default (humidity also readable on-display)
- max load
- 3A resistive (~690W) / 1A inductive
- ip rating
- IP21 (protected against vertically falling drips)
- dimensions
- 86 x 87mm faceplate; requires backbox at least 35mm deep
- external sensor
- Supports NTC 10kOhm external floor/temperature probe