Smart radiator thermostats (list of the best) help to heat rooms optimally and save energy at the same time (guide). They also allow temperature settings to be made conveniently via an app. For optimal temperature adjustment, it also makes sense to use external temperature sensors that are positioned where people are.
This makes it possible to control the room temperature more precisely than if only the sensor in the radiator thermostat is used. Ultimately, this is influenced by the radiation effects of the radiator. Since the open window detection in the devices is usually based on a sharp drop in room temperature, the devices react faster with the help of additional window sensors and thus save more energy than in standard mode. With additional smart sensors and devices, users can even take further measures for an optimal indoor climate (guide) and for better air quality (guide).
With the radiator thermostat Kasa KE100 Kit, TP-Link offers a solution that, together with a gateway, can control up to 32 thermostats. Our test report shows how well the Kasa KE100 works in practice.
Design, functions and scope of delivery
With a diameter of 56.5 mm and a length of 84 mm, the Kasa KE100 is relatively compact. And the hub, with which up to 32 thermostats can be connected, is not particularly large with dimensions of 72 × 70.3 × 51 mm. It is simply plugged into a socket and then connected to the home WiFi router via the 2.4 GHz network using the Kasa app. Communication between the hub and thermostat takes place in the long-range sub-GHz band (Europe: 868 MHz). The distance between the thermostat and the hub can be up to 45 meters, according to TP-Link.
The thermostat cannot yet be paired with the currently available sensors from TP-Link. But by the middle of the year, TP-Link wants to unify the two smart home apps Tapo and Kasa. The KE100 should then also be controllable by the Tapo app, so that it can be linked to motion and window open sensors from the Tapo line.
The Kasa KE100 is compatible with the radiator valve thread M30x1.5. The scope of delivery also includes three adapters for the Danfoss standard RA, RAV and RAVL. While the thread for the M30 connection is made of metal, the Danfoss adapters are made of plastic, as is the case with most smart radiator thermostats. The Kasa KE100 is powered by two AA/LR6 batteries with 1.5 volts. The use of rechargeable batteries or AA models with 1.2 volts is not possible. According to the manufacturer, the two AA batteries should ensure that the thermostat will operate for up to one year. Of course, the more often the thermostat has to adjust the radiator valve to regulate the temperature, the faster the batteries will be exhausted.
The thermostat offers a rotary control in the front area of the housing for manually setting the desired target temperature. In our opinion, this is also the best option, as no one has to get used to it. And if there are children in the household who like to fiddle with the thermostats, you can activate a child lock via the app so that the temperature setting is deactivated using the rotary control.
In the back part of the thermostat housing there are LEDs on the top that show the set temperature, the battery status, as well as the WiFi connection and the operating mode such as heating according to plan (clock symbol). This is solved in a practical way as with the Homematic IP Evo (test report) and Shelly TRV (test report). You don’t have to bend down to read the temperature, as is the case with thermostats whose display is oriented forward or sideways depending on the installation.
Commissioning and settings
Commissioning the Kasa KE100 is not quite as easy as the Shelly TRV with integrated battery. Finally, you first have to plug the hub into a socket and insert the two AA batteries supplied into the thermostat. But before you do that, the thermostat should be screwed to the radiator, as the calibration process starts immediately after inserting the batteries.
The battery compartment is accessible by loosening the front cover using the plastic clip provided and opening the metal clip on the battery compartment. After inserting the batteries, close the battery compartment and housing and begin pairing the hub and thermostat with the Kasa app. An installation wizard with detailed explanations and helpful illustrations guides you through the setup, which is completed in just a few minutes. Using the app requires a TP-Link account (see also image gallery).
TP-Link Kasa KE100
Pictures
The internal temperature sensor of our test model does not record the room temperature correctly when delivered. This is also the case with most other radiator thermostats. Finally, the radiation effect of the radiator ensures that temperatures measured near it are often higher than the actual room temperature. In the device settings you can use the option Temperature deviation make appropriate adjustments. There, users can also activate the child lock, adjust the temperature setting for frost protection and switch on night mode. The latter ensures that the thermostat makes fewer valve adjustments during the night and therefore works more quietly than during the day. You can also activate the energy-saving sleep mode in the device settings. This offers two states: valve completely closed or valve completely open. The first option makes sense during the summer months. However, unlike the Shelly TRV (test report), the Kasa KE100 does not offer protection against valve jamming.
Otherwise, the app offers a clear display. On the home page (power consumption) there is a large button with which you can switch the thermostat on and off. You can use the buttons at the bottom to switch between power consumption (on/off switch) and temperature. The latter shows the current and target temperature. Users can regulate the temperature in increments of one using the plus and minus signs or the adjustment ring on the temperature scale. The report contains the display of the temperature curve, with the set target values depending on the time, as well as the value for the frost protection setting.
Heating schedules and automations
In addition to manually adjusting the target temperature, users can Smart control Create heating plans that automatically control the thermostat. You can choose from the periods Monday to Sunday, Monday to Friday with individual control for Saturday and Sunday, as well as individual days. In other words, you can create plans that apply every day, or differentiate between weekdays and weekends, or that can be adjusted daily. However, the Kasa KE100 does not support location-based control (geofencing).
Smart home and voice control
Users can also control the TP-Link thermostat Kasa KE100 by voice. The app offers link options to Amazon Alexa and Google Assistant (see also image gallery). As mentioned at the beginning, TP-Link plans to make the Kasa thermostat available in the Tapo app with an update in the second half of the year. Combination options with Tapo sensors such as window open detection may then be conceivable. However, the thermostat cannot be paired with other smart home centers (best list) such as Homey Pro (test report), Home Assistant or Apple Homekit (guide).
Prices
TP-Link offers the set consisting of the Kasa KE100 radiator thermostat and the Kasa KH100 hub for just under 100 euros. For Prime Day, the set consisting of gateway and radiator thermostat is available for just under 40 euros. Users can control up to 32 thermostats with the hub. The Kasa KE100 costs 70 euros individually. It is currently available for just under 30 euros.
Conclusion
The smart radiator thermostat TP-Link Kasa KE100 Kit impressed in the test with its easy commissioning and operation. It responds quickly to user input and has no weaknesses in terms of range thanks to sub-GHz wireless technology. With the intuitive app, heating plans can be created in no time. And you can also check while you’re on the go whether the smart thermostat is working as desired, for example via the temperature curve shown in the app.
But there are also a few things that we didn’t like. The Kasa KE100 offers neither open window detection nor geofencing. And it is also incompatible with Homekit and other smart home centers such as Homey Pro and Home Assistant. After all, TP-Link is planning an update at the beginning of the second half of the year that will make it possible to use the Kasa KE100 with the Tapo app. The various sensors from this line should then be able to be connected to the thermostat and ensure that the heating is stopped when the window is opened. As soon as that is the case, we will update this article. And in the fourth quarter, TP-Link plans to introduce a Matter-compatible hub with which you can pair the Kasa KE100 so that it also benefits from the standard. A coupling with other Matter-compatible smart home centers is then conceivable.
TechStage offers more information about smart thermostats and energy saving potential using smart technology in the Smart Home topic world and in the following articles:
More information about radiator thermostats can also be found in our individual and comparison tests:
Note: The original article appeared in April 2023. We will update this if there are particularly attractive offers.