Der Spiegel tested 13 smart radiator thermostats designed to save energy via app. The devices provide precise control, but manufacturers' claims of up to 30 percent savings are exaggerated. Realistic heating cost reductions range from 2 to 15 percent, depending on user habits.
Smart radiator thermostats allow more precise heating control than manual valves to prevent energy waste. Installation is straightforward and does not require professionals; old regulators can be replaced with simple tools like a water pump pliers. Sensors and apps detect open windows or absence and automatically turn off heating. According to consulting firm co2online, forgetful users benefit most, while disciplined ones gain from centralized control of all radiators via smartphone or voice command.
In Der Spiegel's test, last updated on February 3, 2025, with two new models, Tado emerged as the best combination of user comfort and features. It integrates seamlessly into smart home systems but requires high purchase costs and a subscription for full automations, delaying payback. Cheaper options like Aqara, SwitchBot, and TP-Link pay off faster, offer extensive functions without subscriptions, and support standards like Matter for broad compatibility.
AVM Fritz!DECT 302 suits households with Fritzbox, without new software. Homematic IP expands to a full smart home. Evaluated were design, installation, operation, smart functions, and additional costs. Prices range from 40 euros for SwitchBot to 100 euros for Tado X. Battery replacements and potential gateways increase ongoing costs; payback can take up to ten years.
Test criteria included intuitive apps, offline capability, and integration with platforms like Apple Home or Google. No model detects windows perfectly without add-on sensors, and geofencing works for many only with internet or third-party services.
