Bosch Smart radiator thermostat II [+M]

Bosch Smart radiator thermostat II [+M]

4.2
142 ratings
Launch Year: 2023

Model: BTH-RAD

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Our review

Bosch Smart Radiator Thermostat II Review: Sturdy Build Meets Broad Ecosystem Support

A well-built, Matter-ready valve with wide smart home compatibility, let down by some setup friction and occasional dropped connections.

The verdict

The Bosch Smart Radiator Thermostat II [+M] is a Zigbee and Thread-capable valve built for buyers who want one device to work across Google Home, Alexa, Apple HomeKit, Samsung SmartThings, Home Assistant and Matter. Owners consistently rate the build quality and app control as a step up from the first generation, with child lock and frost protection covering the basics well, but a number of reviewers hit friction pairing to non-Bosch Matter bridges or occasional disconnects during daily use. It suits buyers who value a sturdy, multi-ecosystem valve and are comfortable with a bit of hub setup, less so those chasing the cheapest option or expecting flawless third-party Matter bridging out of the box.

Best for
  • Multi-ecosystem smart homes (HomeKit, Alexa, Google Home, SmartThings)
  • Bosch Smart Home Controller households
  • Buyers prioritizing build quality over price
  • Home Assistant users comfortable with Zigbee pairing

Pros

  • Sturdier build quality than the previous Bosch generation
  • Wide ecosystem support: Google Home, Alexa, Apple HomeKit, SmartThings, Home Assistant
  • Matter support built in
  • Frost protection and child lock included
  • On-device display shows current temperature
  • Convenient remote app control

Cons

  • Third-party Matter bridge pairing can be inconsistent
  • Some users report occasional disconnects after setup
  • Zigbee pairing code is inside the battery compartment, best noted before mounting
  • No external temperature sensor or geofencing support
  • Scheduling is manual only, no automatic learning or suggestions
  • Priced higher than some Zigbee-only competitors

Who is the Bosch Smart Radiator Thermostat II for?

This valve is aimed at smart home owners who want broad platform flexibility from a single radiator thermostat, especially those already using a Bosch Smart Home Controller or mixing ecosystems like Apple Home, Alexa, Google Home and Samsung SmartThings. It also appeals to buyers upgrading from an older or less durable valve, since several reviewers specifically compare it favorably to the previous Bosch generation and to other brands' thermostats on build quality.

What buyers love

The most repeated praise is for build quality and day-to-day control: owners describe the housing as noticeably sturdier than the first-generation Bosch valve and than some competing thermostats, and app-based temperature control from anywhere is called out as genuinely convenient. Buyers appreciate that it works across a wide range of ecosystems, Google Home, Alexa, Apple HomeKit, Samsung SmartThings and Home Assistant, without being locked to one platform, and several note that setup on the radiator itself is quick and straightforward. Frost protection and child lock are mentioned as useful, practical safeguards for households with kids or unheated rooms.

What to know before you buy

Despite being marketed with Matter support, a few reviewers report friction connecting it to third-party Matter bridges (such as non-Bosch hubs), with unclear instructions for anything outside Bosch's own ecosystem, so Matter compatibility is more reliable within Bosch's own setup than as a universal bridge. Some owners also report occasional disconnects after the initial setup period, and Home Assistant users note that Zigbee pairing requires an installation code printed inside the battery compartment, which is easy to miss if the valve is mounted before pairing. The valve does not support external temperature sensors, geofencing, or automatic schedule learning, control is manual scheduling only, and there is no humidity sensor.

Is the Bosch Smart Radiator Thermostat II worth it?

For buyers who want a well-built valve with unusually broad ecosystem support (HomeKit, Alexa, Google Home, SmartThings, Home Assistant and Matter all in one device), the II [+M] delivers, and the sturdier housing addresses a common complaint about smart TRVs wearing out. It sits at a higher price point than some Zigbee-only competitors, so it makes the most sense for buyers who value that cross-platform flexibility and durability over chasing the lowest price, and who are prepared for some setup care if pairing through Home Assistant or a non-Bosch Matter bridge.

Frequently asked questions

Does the Bosch Smart Radiator Thermostat II work with Apple HomeKit?

Yes, Apple HomeKit is supported, along with Google Home, Alexa, Samsung SmartThings, Home Assistant and Matter. It does not support IFTTT.

Does it need a hub?

Yes. It connects via Zigbee, which needs a Zigbee hub, or via Thread, which needs a Thread Border Router. It has no direct Wi-Fi or Bluetooth connection.

Does it support Matter?

Yes, Matter is supported, though some reviewers report connecting to non-Bosch Matter bridges can require extra troubleshooting compared with pairing directly through Bosch's own ecosystem.

Does it have child lock and frost protection?

Yes to both. Child lock disables manual adjustments on the device itself, and frost protection automatically heats to prevent pipes freezing in cold weather.

Can it use an external temperature sensor?

No, this model does not support connecting an external temperature sensor; it relies on its own built-in sensor.

How long does the battery last?

It runs on 2x AA batteries with a rated battery life of about 2 years.

At a glance

Summary

Everything this radiator valve supports, grouped by category.

Size & Materials
2 × 2 × 3.4 in (51 × 51 × 87 mm)4.8 oz (135 g)
Connectivity
Zigbee (Zigbee Hub required)Thread Protocol (Thread Border Router required)
Integrations
Google HomeAlexaApple HomeKitSamsung SmartThingsHome AssistantMatter
Sensors
Temperature
Scheduling
Manually
Features
Frost ProtectionChild LockDisplay Temperature

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Company
Bosch logo

Bosch

4.3/ 5 avg ratingGermany flagHeadquartered in Germany

Bosch is a major German engineering company whose Bosch Smart Home line covers heating control, security sensors, smart plugs and cameras. The system centers on a Bosch Smart Home Controller and emphasizes data privacy with local control. Bosch appeals to users in Europe looking for a reliable, well-engineered smart home ecosystem.

Full specifications

Every spec, organized

Browse the full breakdown by category. Tap the on any row for what it means, or the for sources and documentation.

Size & Materials
Dimensions

2 × 2 × 3.4 in (51 × 51 × 87 mm)

Weight

4.8 oz (135 g)

Power
Battery Type

2x AA

Battery Life

2 years

Connectivity
2.4 GHz WiFi

NO

5 GHz WiFi

NO

Bluetooth

NO

Z-Wave

NO

Zigbee

Zigbee Hub required

Thread Protocol

Thread Border Router required

Integrations
Google Home

YES

Alexa

YES

Apple HomeKit

YES

Samsung SmartThings

YES

Home Assistant

YES

Matter

YES

Display
Screen

YES

Screen Type

?

Sensors
Temperature

YES

Humidity

NO

Scheduling
Manually

YES

Automatically

NO

Suggestions

NO

Features
External Temperature Sensors

NO

Geofencing

NO

Frost Protection

YES

Prevents damage to radiators owing to open windows or unused rooms.

Child Lock

YES

Children’s hands on radiator thermostats often lead to incorrect settings and wasted energy. But there is no need to sweat (or freeze) as a result:

Specify in the app or using the operating button on the device that manual settings on the device itself are no longer possible.

This way, kids cannot adjust anything on the smart thermostats, and you can still control the room temperature conveniently via app, voice assistant or room thermostat.

Display Temperature

YES

Automations

YES

Required to work

You need a Zigbee hub for this

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Why it needs a Zigbee coordinator

The Bosch Smart radiator thermostat II [+M] speaks Zigbee, not Wi-Fi. On its own it cannot reach your phone, your voice assistant or any automation: it needs a Zigbee coordinator to join. These are the ones in our catalog that can run it.

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