X-Sense STH0B Smart Thermometer Hygrometer Review: A Screenless Sensor Built Around the SBS50 Base Station
Tight quoted accuracy, dew point and VPD tracking and free CSV export, on a probe that cannot report a single reading without an X-Sense base station.
The X-Sense STH0B is a screenless temperature and humidity probe made for homes that already run an X-Sense SBS50 base station. It carries no Wi-Fi of its own: it talks to that base station over a proprietary 868 MHz radio rated for up to 500 m in the open, and the base station is what puts the readings on the network. What it gives back is a tight spec sheet, typically within 0.2 C and 2% RH, a year on two replaceable AAA batteries, push alerts for temperature, humidity and low battery, and free history with dew point and VPD plus CSV export. The trade-offs are structural rather than fixable: no display, no automation engine, and a platform list that ends at Alexa and Home Assistant. As a cheap add-on sensor for an existing X-Sense system it is easy to justify; bought on its own, without the base station, it does nothing at all.
- Existing X-Sense base station owners
- Plant, greenhouse and grow-space monitoring
- Cabins, garages and storage rooms far from the router
- Budget buyers adding several rooms at once
One sensor per room you want to read.
Buy on Amazon USAPros
- Typical accuracy of 0.2 C and 2% RH, specified across a wide -20 to 60 C range
- Proprietary 868 MHz link rated for up to 500 m from the base station in the open
- About a year of runtime on two replaceable AAA batteries
- Temperature, humidity and low battery alerts as push notifications, with an optional base station alarm
- Free history with dew point and VPD, plus scheduled CSV export of up to 180 days per file
- Voice queries through Alexa, and Home Assistant support via the X-Sense custom integration that names this model
- Two year warranty
Cons
- No screen of any kind, just a red and blue indicator light, so every reading lives in the app
- Useless without an X-Sense SBS50 base station, which is sold separately
- The base station's Wi-Fi is 2.4 GHz only and will not join a 5 GHz network
- No Google Home, Apple Home, SmartThings or Matter support
- No automation engine, so readings cannot trigger devices outside the X-Sense system
- Not waterproof, so it is limited to indoor and sheltered placements
- Manufacturer publishes no physical dimensions for the sensor
Who is the X-Sense STH0B for?
This is an accessory sensor before it is a product. It joins an X-Sense SBS50 base station over a proprietary 868 MHz link, and that base station holds the 2.4 GHz Wi-Fi connection and relays everything to the X-Sense app, so the STH0B only makes sense for a household that already owns, or is willing to buy, that hub. In exchange for that dependency it gets a radio with far more reach than Wi-Fi, quoted at up to 500 m in the open, which is what makes it usable in a detached garage, a basement three floors below the router, an outbuilding or a greenhouse. The dew point and VPD figures the app derives from the same two readings push it further toward plant and storage monitoring than toward general comfort tracking.
What the X-Sense STH0B offers
The sensing side is the strongest part of the sheet: temperature is specified across -20 to 60 C with typical accuracy of 0.2 C, and humidity across the full 0 to 100% RH range with typical accuracy of 2% RH between 10 and 90%. Alerts are set as ranges in the app, and crossing one sends a push notification and sounds the base station, which can be silenced so only the notification arrives; a low battery warning works the same way, backed by the indicator light. History is free rather than gated behind a plan: the app keeps continuous graphs with maximum, minimum and average values, adds dew point and VPD, and exports up to 180 days per CSV file, with daily, weekly or monthly scheduled exports. Two replaceable AAA batteries carry it for about a year, and the warranty runs two years.
What to know before you buy
There is no screen. The only thing on the body is a red and blue indicator light, so walking up to the sensor tells you nothing and every reading is read in the app, which in turn depends on the base station and its Wi-Fi being up. That Wi-Fi is 2.4 GHz only and will not join a 5 GHz network. The sensor also has no automation engine, so a reading cannot trigger anything outside the X-Sense system, and the platform list is short: Alexa answers voice queries and Home Assistant reads the account through the community X-Sense integration, but there is no Google Home, Apple Home, SmartThings or Matter path. It is not waterproof either, which rules out unsheltered outdoor placement and long spells in condensing humidity.
Is the X-Sense STH0B worth it?
Judged as a standalone gadget it is poor value, because on its own it cannot report anything. Judged as what it actually is, an inexpensive probe that drops into an X-Sense base station already installed for smoke, carbon monoxide or leak alarms, the arithmetic changes: it is one of the cheapest ways to add a room, and the long-range radio reaches places a Wi-Fi sensor cannot. Buyers who want a number they can read on the device itself, or a sensor that triggers a humidifier through a third-party platform, are shopping in the wrong part of the category and should look at a display model or one that speaks a standard protocol.
Frequently asked questions
Does the X-Sense STH0B work without a base station?
No. The sensor has no Wi-Fi of its own and communicates over a proprietary 868 MHz radio, so an X-Sense SBS50 base station is required to receive the readings and pass them to the app. The base station is sold separately.
Does the X-Sense STH0B have a display?
No. The body carries only a red and blue indicator light. Temperature, humidity, dew point, VPD and history are all shown in the X-Sense Home Security app.
Which smart home platforms does it work with?
Alexa, for voice queries of the temperature and humidity readings, and Home Assistant through the community X-Sense custom integration that lists this model. It does not support Google Home, Apple Home, SmartThings or Matter.
How accurate is the X-Sense STH0B?
The manufacturer specifies typical accuracy of 0.2 C from 0 to 60 C and 0.2 to 0.4 C below freezing, with typical humidity accuracy of 2% RH between 10 and 90% RH. It operates from -20 to 60 C and across 0 to 100% RH.
How long does the battery last and what type does it use?
It runs on two replaceable 1.5 V AAA alkaline batteries and is rated for about one year per set. A low battery warning appears in the app and the indicator light flashes once every 60 seconds.
Can I export the data, and does it cost anything?
Yes, and no. The app exports readings as CSV at no charge, up to 180 days per file, and a scheduled export can be set to run daily, weekly or monthly.
Can the X-Sense STH0B be used outdoors?
It is not waterproof, so it should stay indoors or in a sheltered spot. The manual also advises against long term use above 80% RH where condensation can form.
