1. Introduction
Thank you for choosing the ISNATCH Smart Wi-Fi Chronothermostat. This device is designed to provide intelligent control over your heating and cooling systems, offering both local soft-touch operation and remote management via the HeySmart smartphone application. It features weekly programming, frost protection, and holiday functions, and is compatible with Amazon Alexa and Google Home voice assistants.
Please read this manual carefully before installation and operation to ensure proper use and to maximize the benefits of your new thermostat.
2. Safety Information
- Electrical Installation: Installation must be performed by a qualified electrician in accordance with local electrical codes. Ensure the main power supply is disconnected before any wiring work.
- Power Supply: The thermostat requires a direct 230V AC power supply. Do not connect to other voltage sources.
- Operating Environment: Use the device within the specified operating temperature range of +5°C to +35°C. Avoid exposure to extreme temperatures, humidity, or direct sunlight.
- Cleaning: Clean the device with a soft, dry cloth. Do not use abrasive cleaners or solvents.
- Children: Keep the device out of reach of children.
3. Package Contents
Verify that all items are present in the package:
- ISNATCH Smart Wi-Fi Chronothermostat (Black, Soft-Touch)
- Integrated NTC Sensor (10 K) 1%
- Passive Relay (max. 5A)
- User Manual (this document)
- Mounting accessories (screws, etc. - if applicable, not explicitly listed but implied for installation)

Image: The ISNATCH Smart Wi-Fi Chronothermostat, featuring a black soft-touch panel with a backlit display showing time, temperature, and Wi-Fi status.
4. Installation and Setup
4.1 Electrical Installation
- Power Disconnection: Before starting, ensure the main power supply to your heating/cooling system is turned off at the circuit breaker.
- Mounting Location: The thermostat is designed for installation directly onto a standard 503 box.
- Wiring: Connect the thermostat to a direct 230V AC power supply. Follow the wiring diagram provided with your specific heating/cooling system and the thermostat's internal wiring instructions. Ensure all connections are secure. The thermostat includes a passive relay with a maximum capacity of 5A.
- Secure Mounting: Mount the thermostat securely to the 503 box using the provided screws.
- Power Restoration: Once installation is complete and all connections are verified, restore power at the circuit breaker.

Image: Diagram illustrating the installation of the thermostat onto a 503 box, showing connections to a Wi-Fi router and a heating/cooling unit, powered by 230V AC.
4.2 HeySmart App Setup (Wi-Fi Connection)
To enable remote control and smart features, connect your thermostat to the HeySmart app:
- Download App: Download the "HeySmart" app from your smartphone's app store (available for iOS and Android).
- Register/Login: Open the app and register for a new account or log in if you already have one.
- Add Device: Follow the in-app instructions to add a new device. This typically involves putting the thermostat into pairing mode (refer to the thermostat's display for pairing indicators, usually a flashing Wi-Fi icon).
- Connect to Wi-Fi: Select your 2.4 GHz Wi-Fi network and enter the password when prompted by the app. The thermostat will connect to your home Wi-Fi network.
- Device Naming: Assign a name to your thermostat within the app (e.g., "Living Room Thermostat").

Image: The ISNATCH thermostat displaying its interface, with a smartphone nearby showing the HeySmart app interface, indicating compatibility and remote control capabilities.
5. Operating Instructions
5.1 Local Control (Soft-Touch Panel)
The thermostat features a soft-touch panel for direct control. Specific button functions may vary slightly, but generally include:
- Power Button: Turns the thermostat on/off.
- Mode Button: Switches between heating and cooling modes.
- Up/Down Arrows: Adjusts the target temperature.
- Menu/Settings Button: Accesses advanced settings and programming options.
- Clock/Program Button: Sets time and activates weekly programming.
Refer to the on-screen prompts and the detailed instructions within the HeySmart app for specific button sequences and menu navigation.
5.2 Remote Control (HeySmart App)
The HeySmart app provides full control over your thermostat from anywhere with an internet connection:
- Temperature Adjustment: Easily set the desired temperature.
- Mode Selection: Switch between heating and cooling modes.
- Weekly Programming: Create and modify detailed weekly schedules for optimal comfort and energy saving.
- Frost Function: Activate the frost protection feature to prevent pipes from freezing when away.
- Holiday Function: Set specific temperature profiles for extended periods when you are away from home.
- Scenario Creation: Integrate your thermostat with other HeySmart devices to create automated scenarios (e.g., "Away" scenario turns off heating and lights).

Image: A hand holding a smartphone displaying the HeySmart app, which shows a temperature setting of 19.5 degrees, with the ISNATCH thermostat mounted on a wall in the background, demonstrating remote control.
5.3 Voice Assistant Control
The ISNATCH Smart Wi-Fi Chronothermostat is compatible with Amazon Alexa and Google Home. To enable voice control:
- Link Account: In your Alexa or Google Home app, search for the "HeySmart" skill/service and link your HeySmart account.
- Discover Devices: Once linked, ask your voice assistant to "discover devices."
- Voice Commands: You can now use commands such as:
- "Alexa, set [Thermostat Name] to 22 degrees."
- "Hey Google, what's the temperature in the [Thermostat Name]?"
- "Alexa, turn on [Thermostat Name]."
6. Maintenance
The ISNATCH Smart Wi-Fi Chronothermostat requires minimal maintenance.
- Cleaning: Periodically wipe the thermostat's surface with a soft, dry, lint-free cloth to remove dust and smudges. Do not use liquid cleaners, sprays, or abrasive materials, as these can damage the soft-touch panel and internal components.
- Software Updates: Ensure your HeySmart app is always updated to the latest version to receive new features and performance improvements for your thermostat. The thermostat's firmware may also receive updates via the app.
7. Troubleshooting
If you encounter issues with your thermostat, refer to the following common problems and solutions:
| Problem | Possible Cause | Solution |
|---|---|---|
| Thermostat not powering on. | No power supply or incorrect wiring. | Check the circuit breaker. Verify 230V AC power connection and wiring according to installation instructions. Consult a qualified electrician if unsure. |
| Cannot connect to Wi-Fi. | Incorrect Wi-Fi password, 5GHz network, or weak signal. | Ensure you are connecting to a 2.4 GHz Wi-Fi network. Double-check the Wi-Fi password. Move the thermostat closer to the router or improve Wi-Fi signal strength. Restart your router and the thermostat. |
| Remote control not working. | No internet connection, app issues, or thermostat offline. | Check your home internet connection. Ensure the thermostat's Wi-Fi indicator is solid. Restart the HeySmart app. Verify the thermostat is online in the app. |
| Temperature readings seem inaccurate. | Thermostat placed near heat sources/drafts, or sensor issue. | Ensure the thermostat is not exposed to direct sunlight, drafts, or heat-emitting appliances. If the issue persists, contact support. |
| Heating/Cooling system not responding. | Wiring issue, system malfunction, or thermostat mode. | Verify the thermostat is in the correct mode (heating/cooling). Check wiring connections to the heating/cooling system. Ensure the system itself is operational. |
8. Specifications
| Model Number: | 49683035 |
| Product Dimensions: | 130 x 90 x 29 mm (approx. 2.9 x 9 x 2.9 cm) |
| Weight: | 350 g |
| Power Supply: | 90 ~ 240 V AC |
| Operating Temperature: | +5 ~ +35 °C |
| Sensor Type: | Built-in NTC sensor (10 K) 1% |
| Relay: | Passive relay max. 5A |
| Wi-Fi Frequency: | 2.4 GHz |
| Installation: | Overhang to Box 503 |
| Color: | Black |
| Connectivity: | Wi-Fi |
| Special Features: | Compatible with Amazon Alexa and Google Home, Programmable Temperature Control |
9. Warranty and Support
For warranty information, please refer to the terms and conditions provided by your retailer at the time of purchase. ISNATCH products are designed for reliability, but should you encounter any issues or require technical assistance:
- HeySmart App: The HeySmart app often includes a support section or FAQs that can help resolve common issues.
- Retailer Support: Contact the retailer from whom you purchased the product for initial support and warranty claims.
- Manufacturer Support: Visit the official ISNATCH website for further support resources, contact information, and updated documentation.