Buy a better measuring point, not another temperature number
The Wireless Temperature Sensor X is most useful when the radiator gets comfortable before you do. A valve behind curtains, beside a hot pipe or trapped behind furniture can measure a different temperature from the sofa. This sensor lets a Tado X room follow a reading from a more representative spot.
It also puts physical temperature buttons where someone can reach them. In a room with several Tado radiator valves, a single controller can set the room target and provide the measuring point. That is a worthwhile improvement over bending down to several radiators or requiring every family member to use an app.
At about €70 or £70 on offer in Germany and the UK, it needs to solve that problem. Buying one simply to display another temperature number is difficult to justify when the existing room already stays comfortable.
Try the free adjustment before buying
Tado allows a temperature offset when a device consistently reads too warm or too cold. That may be enough if the difference is predictable. Without a separate room controller, Tado uses the average of the room's radiator-valve measurements. A wired thermostat or wireless temperature sensor can instead act as the measuring device.
A better-located sensor is more appealing where the radiator's immediate surroundings vary too much for one offset to represent the room well. It is still only as useful as its position: direct sunshine or a draft can make the new reading unrepresentative too. Moving the measurement is the improvement; a second sensor is not automatically a more accurate one.
The older controls remain perfectly reasonable
This first-generation SU04 has a backlit LCD, three physical buttons and three AAA batteries. It can be wall-mounted using the supplied fittings or adhesive pads. A tabletop stand is a separate accessory, not included in the store's listed box contents.
The 100 × 100 mm square has a black front, white housing and a plain, functional look. For a busy family room, the simple buttons and replaceable cells may be exactly what you want. It works alongside second-generation Tado X products, so a working one does not need replacement just because newer hardware is available.
Both sensors carry the same full price, about €100 or £90. Most of Tado's shops currently discount this older one more deeply, so the second generation costs about €10 more in Germany and Austria and about £20 more in the UK, and nothing more in Tado's store for France, Spain and the rest of Europe. That small premium, or none, buys a thinner body, rechargeable power, a light ring and a shortcut button, so choose this older sensor only if you specifically want physical buttons and AAA cells. A wired thermostat may look similar, but has a different job and needs the heating connection.
It belongs to a heating system
The sensor cannot turn a boiler or radiator on by itself. It needs the appropriate Tado X room hardware and a compatible Thread border router. A wireless starter kit already contains a sensor and a receiver, so buy another one only for a second room or a different measuring spot.
Matter lets SU04 share its supported room controls and readings with other home apps. It does not make this a drop-in remote sensor for a Nest, Eve or unrelated boiler thermostat. The Tado room assignment and coordination remain essential to its main purpose. Older V3+ hardware also cannot share the same Tado Home with X.
Buy it for a cold seating area, inaccessible valve controls or a room with several Tado radiators that needs one measuring point. Keep an existing SU04 that already does those jobs. Skip it when the free offset works, or when you only need a general temperature sensor for an unrelated automation.
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