Typically used for
Thermostat
Floor heating
Heating & Cooling
Energy saving
Valves
Key Features
Underfloor heating valve control
Fan coil control
Ventilation fan control - AC and DC fans supported, including 10V DC fan control via an analog output
Heat source control - Uses a dry contact relay to signal heat sources like gas burners, pellet burners, etc.
Supports electric underfloor heating - The thermostat can signal a connected Shelly relay to switch the heating on or off automatically based on temperature settings
RS485/ MODBUS control
Coming soon
Anti-freeze function - prevents damage to the heating pipes
Humidity sensor integrated
Temperature & humidity offsets - Adjust the thermostat’s readings to make them more accurate
No hub required! Wi-Fi and Bluetooth connectivity
Wi-Fi Range Extender & BLE Gateway
Powered by Shelly - Equipped with a Shelly chip, offering full Shelly capabilities
Smart schedules based on time or sunset/sunrise
Highly compatible! Easy control through the Shelly Smart Control app, most automation platforms and open documented protocols. Support for Alexa and Google Home coming soon.
Device identification
Device type: Smart thermostat
Device model: ST802-B
Main features
Underfloor heating valve control
Fan coil control
Ventilation fan control - AC and DC fans supported, including 10 V DC fan control via an analog output
Dry contact relay to signal heat sources like gas burners, pellet burners, etc.
Supports electric underfloor heating - The thermostat can signal a connected Shelly relay to switch the heating on or off automatically based on temperature settings
RS485/ Modbus control
Anti-freeze function - prevents damage to the heating pipes
Humidity sensor integrated
Temperature & humidity offsets
Wi-Fi and Bluetooth connectivity
Connectivity
Wi-Fi
Bluetooth
RS485 / Modbus
User interface
Room relative humidity.
ON/OFF button, hold on the button until the Wi-Fi icon is displayed.
Room temperature.
Switch fan speed.
Current fan speed.
Mode selection button.
Up and Down button for adjust set point.
The Wi-Fi signal will be displayed after connected to internet.
Show the current setting mode.
Specification | Value |
|---|---|
Device type | Smart thermostat |
Model | ST802-B |
Size (H x W x L) | 86.8 x 86.8 x 14 mm (see Fig. 1: Device dimensions for more details) |
Input voltage | 90 - 240 VAC, 50/60 Hz |
Load current | 2A resistive load, 1A inductive load |
Temperature control range | +5 to +35°C |
Working environment | -10 to +55°C |
Protection level | IP20 |
Fig. 1: Device dimensions Wiring diagram
Legend:
A1/B1: RS485
A2/B2: RS485
C1/C2: Digital output
H: High speed
M: Medium speed
Lo: Low speed
Valve (NO/NC): Fan coil valve
FL: Floor heating valve
L: Live
N: Neutral
What are the differences between the different generations of Shelly products?
Each new generation adds more power, memory, and features:
Gen 1 offers basic control;
Gen 2 (Plus Series, Mini Series, Pro Series) adds Bluetooth, scripting, and better security;
Gen 3 improves performance, adds Matter (starting from firmware version 1.6.0 or newer) and advanced monitoring;
Gen 4 offers multi-protocol connectivity, featuring Wi-Fi 6, Bluetooth, Zigbee, and Matter.
Can I control the device via Bluetooth?
No, the protocol is used only for device inclusion, allowing for quick and easy setup through the Shelly Smart Control app.
For bluetooth control it is required to have another Bluetooth device such as Shelly BLU Button or Shelly BLU Motion to interact.
Additionally, Shelly devices can function as a BLE gateway, bridging Shelly BLU devices to your Wi-Fi network.
Is it possible to use the device without a hub?
Yes, Shelly devices (except for Wave devices) operate independently without the need for a hub. They connect directly to your Wi-Fi network, and you can control them via the Shelly Smart Control app, web interface, or through integrations with platforms like Google Home, Alexa, Home Assistant and Samsung SmartThings.
Use cases
Smart Climate Control for Any Space
Control heating, cooling, and dehumidification in your home or office. Set custom schedules, adjust settings based on temperature and humidity, and manage everything remotely for consistent comfort and energy efficiency.
Control the heat source of your installation
The thermostat can also signal the heat source of your installation to start or stop using the integrated dry contact relay. This capability allows the thermostat to operate independently or in combination with other heat control equipment
Integrate into a larger HVAC system
Designed for both standalone and large-scale HVAC installations, the thermostat supports RS485/MODBUS integration, making it easy to connect with centralized climate control systems.
Protect Your Heating System from Freezing
The anti-freeze function ensures your heating system stays safe, even when you’re away for extended periods. By keeping room temperatures above minimum, it prevents pipes from bursting and protects your home from damages.