1. Introduction
This manual provides essential information for the proper installation, operation, and maintenance of your Viessmann Vitotrol 300 A wired remote control unit (model Z008342). The Vitotrol 300 A is designed to enhance the control of your Viessmann heating system, offering precise adjustments and monitoring capabilities.
2. Safety Instructions
Please read these safety instructions carefully before installing or operating the device. Failure to follow these instructions may result in property damage, personal injury, or death.
- Installation and maintenance must only be carried out by qualified personnel.
- Ensure the power supply to the heating system is disconnected before any installation or wiring work.
- Do not expose the unit to moisture or extreme temperatures.
- Keep packaging materials away from children.
3. Product Overview
The Viessmann Vitotrol 300 A is a wired remote control unit designed for integration with Viessmann Vitotronic 200 heating controls. It functions as a KM-BUS participant, allowing for comprehensive control and monitoring of your heating system.

Image 1: The Vitotrol 300 A remote control unit, showing its display and control buttons, alongside mounting screws, wall plugs, a connector, and a cleaning cloth.
Key Features:
- KM-BUS Participant: Integrates seamlessly with compatible Viessmann heating systems.
- Temperature Control: Allows setting of room temperature setpoint and reduced room temperature setpoint.
- Hot Water Control: Enables adjustment of hot water temperature.
- Operating Programs: Supports various operating and holiday programs.
- Special Functions: Includes Party and Economy functions for flexible heating management.
- Time Programs: Configurable time programs for heating circuits, domestic hot water cylinder, and domestic hot water circulation pump.
- Illuminated Graphic Display: Provides clear display of outdoor temperature, room temperature, operating statuses, and plain text messages.
- Room Temperature Sensor: Features an integrated room temperature sensor for room temperature influence (applicable for one heating circuit with mixer).
- Buffer Cylinder Status: Displays the charging status of the heating water buffer cylinder.
- Heat Quantity Display: Shows the heat quantity supplied from the environment.
- System Compatibility: A maximum of two Vitotrol 300 A units can be connected per Vitotronic 200 control unit.
4. Installation (Setup)
Proper installation is crucial for the optimal performance of the Vitotrol 300 A. This unit is designed for wired connection.
4.1 Placement
If the Vitotrol 300 A is used for room temperature influence, it must be placed in a main living area (reference room). This ensures accurate measurement of the room temperature for effective heating control.
- Avoid placing the unit near heat sources (e.g., radiators, direct sunlight) or cold drafts (e.g., windows, doors).
- Ensure the unit is mounted at a height that allows for representative room temperature measurement, typically around 1.5 meters from the floor.
4.2 Wiring
The Vitotrol 300 A connects to the heating system via the KM-BUS. Refer to the wiring diagram provided with your main heating control unit (e.g., Vitotronic 200) for specific connection points.
- Ensure all electrical connections are secure and comply with local regulations.
- The unit is supplied with necessary mounting hardware (screws, wall plugs) for installation.
4.3 External Room Temperature Sensor (Optional)
If the Vitotrol 300 A cannot be placed in a suitable location for accurate room temperature detection, an external room temperature sensor (Part No. 7438537) must be ordered separately and connected to the system.
5. Operation
The Vitotrol 300 A features an intuitive interface with an illuminated graphic display and control buttons for easy navigation and setting adjustments.
5.1 Basic Navigation
- Use the arrow buttons to navigate through menus and adjust values.
- Press OK to confirm selections or enter sub-menus.
- The return arrow button allows you to go back to the previous menu.
- The question mark button typically provides context-sensitive help or information.
5.2 Setting Room Temperature
- Navigate to the "Room Temperature" menu.
- Select "Setpoint" to adjust the desired comfort temperature.
- Select "Reduced Setpoint" to adjust the desired temperature during setback periods (e.g., night, absence).
- Use the arrow buttons to change the values and press OK to save.
5.3 Hot Water Temperature Adjustment
Access the "Hot Water" menu to set the desired temperature for your domestic hot water supply.
5.4 Time Programs and Special Functions
The unit allows you to configure weekly or daily time programs for heating circuits, domestic hot water, and circulation pump operation. Additionally, activate "Party" mode for extended comfort heating or "Economy" mode for energy savings outside of programmed times.
6. Maintenance
The Vitotrol 300 A requires minimal maintenance. Regular cleaning and occasional checks are sufficient to ensure its longevity and proper function.
- Cleaning: Wipe the display and casing with a soft, dry, or slightly damp cloth. Do not use abrasive cleaners or solvents.
- Inspection: Periodically check the unit for any visible damage or loose connections.
- Professional Check: It is recommended to have your entire heating system, including control units, inspected by a qualified technician annually.
7. Troubleshooting
If you encounter issues with your Vitotrol 300 A, refer to the following basic troubleshooting steps. For complex problems, contact a qualified service technician.
| Problem | Possible Cause | Solution |
|---|---|---|
| Display is blank | No power supply; loose connection. | Check power to the main heating control unit. Verify KM-BUS wiring connections. |
| Incorrect room temperature reading | Unit placed in an unsuitable location (e.g., near draft or heat source). | Relocate the unit to a more representative area or consider installing an external room temperature sensor. |
| Settings not saving | Configuration error; temporary system glitch. | Ensure you press OK to confirm settings. If problem persists, consult the main heating control unit manual or a technician. |
8. Specifications
| Feature | Detail |
|---|---|
| Model Name | Vitotrol 300 A |
| Manufacturer | VIESSMANN |
| Article Number | Z008342 |
| Connectivity | Wired (KM-BUS Participant) |
| Power Source | No batteries required (powered via KM-BUS) |
| Display | Illuminated Graphic Display |
| Compatibility | Up to 2 Vitotrol units per Vitotronic 200 |
9. Warranty and Support
For warranty information, please refer to the documentation provided with your complete Viessmann heating system or contact your authorized Viessmann dealer. For technical support, installation assistance, or service, please contact a qualified heating technician or Viessmann customer service.
You can find contact details for Viessmann support on their official website or through your local distributor.





