Tech

Smart heating: You should pay attention to this when buying


Smart heating creates comfort and saves energy. This reduces the running heating costs. In this buying guide, we show you what to look for when buying.

When people talk about smart heating, in the vast majority of cases they mean radiator thermostats with an app connection, which replace the old, manual ones. These sit directly on the radiator and regulate the temperature there. We have tested many of them in the past. We show which is the best in the top 10: The best smart radiator thermostats. There is a big comparison in the comparison test 2020: The best smart radiator thermostats. We collect all advice and individual tests on our Smart Heating topic page.

In addition to the radiator thermostats on the radiator, smart solutions are also possible directly on the heating system or on the underfloor heating. They all have location-independent control via smartphone and voice control via Alexa and / or Google Assistant and / or Siri. They often need a bridge, get along with room thermostats and other smart home devices, and offer special functions such as geofencing. This purchase advice gives an overview.

Smart radiator thermostats can be used wherever classic radiators with rotary controls, the thermostat, are in the room. This “stupid” thermostat can now be made “smart”. In the vast majority of cases, this works quite simply. All you have to do is loosen a screw ring with a pipe wrench or a French, remove the old thermostat and replace it with the new one. Great technical understanding is not necessary for this. Nobody has to fear water damage either, as the water cycle remains closed. Installers shouldn’t take too much time, as the radiators can be turned on fully without the thermostat and can get very hot.


It only becomes complicated when the radiator is hidden behind panels or a fitted kitchen, for example. Here you should make sure to buy a relatively small radiator thermostat. The Wiser Heat, Fritzdect 301 and Tado V3 + thermostats are recommended, as they are smaller than Innogy, Homematic IP, Comet DECT, Bosch and Eve Thermo.

The thermostats from Tado have a bayonet lock to make them easier to install in hard-to-reach places. On the other hand, they can be detached from the radiator with a flick of the wrist, for example to replace batteries.

If you have access to the heating system, it becomes confusing. This is simply because there are countless variants, including thermal baths, central heating or district heating. Tenants with central heating do not have the option of installing smart extension boxes there and have to limit themselves to local room control. If you have access, the extension box switches directly in front of the boiler and connects wirelessly or wired to a wall thermostat.

The Homematic-IP control unit for underfloor heating.

Before buying, you should be clear about whether the targeted solution supports your own heating system. If you don’t have an exotic in the basement, that shouldn’t be a problem. Tado claims in his Compatibility Guide for example, to support almost all heating systems. All providers of corresponding solutions provide such a list. The app usually guides you through the installation, which is, however, no longer as simple as replacing a thermostat. If in doubt, we recommend consulting a specialist installer.

Once installed, they work much like a smart radiator thermostat. The extension boxes work best and most reliably with the room solutions in the form of a thermostat from the same manufacturer.

For central control, the thermostats usually communicate via a wireless connection standard with a bridge that is either in the WLAN or directly on the router. But there are exceptions. Eve Thermo (test report) communicates directly with Apple devices via Bluetooth, Android is not supported. A Bluetooth bridge is also available on request, more precise here. With it, the Eve solutions are permanently in the network, so location-independent control, for example from the office, is possible.


Also AVM Fritzdect 301 (test report) and Comet DECT Thermostat (test report) come in a starter pack without a bridge, as they connect directly to a compatible Fritzbox via DECT (7490, 7580 and 7590 in comparison). A bridge is simply not necessary here, which saves money and an additional device that is permanently connected to the power – if you have a DECT-capable router.

Most other smart radiator thermostats use a proprietary radio protocol on 868 MHz. Devolo (test report) relies on Z-Wave and Wiser Heat (test report) on Zigbee. Nevertheless, they absolutely need their own bridge. Because Wiser Heat does not connect to the Zigbee bridge from Philips Hue (test report starter kit) or a Zigbee-enabled Amazon Echo Plus 2 (test report).

The bridges are usually attached to the router via LAN cables. Some like the bridge from Tado use the router’s USB-A port for power supply, others like the bridge from Bosch (test report) require the supplied USB power supply unit. Bridges with WLAN, as offered by Wiser and Netatmo (test report), have the advantage that they can be placed regardless of location and do not block a LAN port on the router.

All smart thermostats come with an app. There the user can determine the current target temperature and set schedules. This usually also works from the cellular network, so it is location-independent. Some thermostats are based on the current outside temperature when setting the temperature. If you switch them off in summer, they turn the heating on and off again at regular intervals so that the valve, the pin on the radiator, remains movable.


All smart radiator thermostats have a temperature sensor, most of them record the actual temperature. Some also measure the humidity and include it in the statistics. On request, many detect a sudden drop in temperature, such as occurs when a window is opened for ventilation, and turn off the heating. Sounds good, but in practice it often works less well than hoped. In some cases we had to put an ice pack on the radiator thermostat to provoke it to turn off. In the case of underfloor heating, such an automatic system does not make sense anyway because of its inertia.

Some systems such as Tado support geofencing, which means that they include the location data of the residents. Tado turns the radiators off when all residents are out and back on when they approach. Others understand complex if-then routines or the IFTTT automation service, which is now chargeable.
Anyone who attaches particular importance to data security should take a look at the solution from AVM and Eve. There, the data is not stored in the cloud, but on the router, or in the devices themselves or on the mobile device.


Basically, all systems respond to calls after being appropriately integrated, making temperature control particularly convenient. Few of them, such as Tado Thermostat V3 + (test report) and Netatmo (test report), know the three big voice assistants from Google, Amazon and Apple. Almost everyone knows Alexa, but not Eve Thermo (test report), who only listens to Siri.

The systems differ significantly in terms of their range of functions and the usability of the app. For a better overview, we recommend our comparison test 2020: The best smart radiator thermostats and then reading the individual tests.

The thermostats use an integrated sensor to determine the room temperature, which, due to the design, is always very close to the radiator. For many, the buyer can set an offset temperature via the app, i.e. always subtract a few degrees from the measured temperature in order to get closer to the actual temperature in the middle of the room. Using a room thermostat is more elegant and accurate. This then hangs, for example, near the couch, where the comfortable temperature should be achieved. Most systems have their own room thermostat for this, but not all.


In general, if there is a corresponding interest in use, when deciding on a system you should make sure that there are other compatible smart home components. For example, a window contact helps to reliably turn off the heating when the window is open.

The prices of the individual thermostats vary from around 25 to 70 euros. In larger households with many radiators, this can add up to considerable amounts. The thermostat from Comet is very cheap, followed by Innogy. Buyers of the Homematic IP, Bosch, Fritzdect 301 and Wiser temperature controllers have to put a little more on the table. The most expensive system comes from Tado. It should be noted here that with Innogy after twelve months and with Tado V3 + from the start, follow-up costs are incurred for some functions in the form of a subscription model.

One AVM Fritzdect 301 thermostat (test report) costs around 45 euros, the compatible Comet DECT thermostat (test report) currently only a good 30 euros. You connect directly to a Fritzbox, there is no additional bridge. This means that entry into the smart heating world with the AVM / Comet solution is relatively cheap, provided you already have a compatible Fritzbox. Bosch smart radiator thermostat (test report) wants 175 euros for its starter set consisting of two thermostats, a window contact and the bridge.

In the starter set of Homematic IP (test report) In addition to a thermostat and the access point, buyers will also find an optical window contact. If you want to integrate the Homematic IP thermostats into your existing Homematic system, you can do without the access point and use the individual thermostats, which cost around 50 euros.

Eve Thermo (test report) costs a good 60 euros each. An iPhone, iPad or Macbook is required for setup and operation. At 135 euros for three thermostats and the bridge, the Innogy starter set is almost a bargain compared to the others. Each Innogy thermostat (test report) costs around 50 euros. Innogy also sells many other compatible smart home components. Attention: Subscription fees apply after twelve months.

The Tado Thermostat V3 + (test report) costs around 110 euros with a thermostat and bridge. With Wiser Heat Thermostat (test report), entry is quite expensive because of the cost-intensive WLAN bridge. The starter set with two thermostats and the bridge costs an impressive 225 euros. Each additional thermostat costs 50 euros.

The price of the Netatmo starter set (test report) with two radiator thermostats and the bridge costs around 160 euros. A single thermostat costs between 60 and 75 euros. This makes them comparatively expensive, but in terms of hardware and software they are among the best on the market.
The Devolo Home Control Smart Heating 2.0 (test report) with two radiator thermostats, the bridge and a room thermostat costs 140 euros, each additional radiator thermostat from 45 euros. But you shouldn’t pay more, as one of the biggest selling points for this system is its low price.

Smart heating is one thing above all: an expensive gain in convenience. Because if you have no problem with regularly working on the radiators and adjusting the temperature, you can save the not inconsiderable costs for the thermostats or the extension box on the heating system. For those who are less disciplined or who consciously want to avoid the daily hike from radiator to radiator, a smart heating system is a real relief. An “Alexa, turn on the heating” is wonderfully quick from the lips.

Nevertheless, you should pay close attention to which system you choose, especially at the beginning. They are only compatible with one another to a limited extent. The price differences are also enormous, especially if, for example, the heating of an entire house is to be smart. We recommend our top 10: The best smart radiator thermostats. There is a big comparison in the comparison test 2020: The best smart radiator thermostats. We collect all advice and individual tests on our smart heating topic page. We stay tuned to the topic and regularly add new products to the articles.

Permalink: https://techstage.de/-4940488

Tags