This manual details the Viessmann Vitodens 100-W WB1B, a wall-mounted gas condensing boiler (7.9-26.0kW) for UK users.
Boiler Overview and Key Features
The Viessmann Vitodens 100-W WB1B is a highly efficient, wall-mounted gas-fired condensing boiler designed for central heating and domestic hot water. Available in natural gas and LPG versions, it boasts an output range of 7.9 to 26.0 kW, making it suitable for various property sizes. Key features include its compact design, ease of installation, and reliable operation.
This boiler is known for its durability and energy efficiency, aligning with Viessmann’s reputation for quality. It’s compatible with low loss headers and can be integrated with multiple heating circuits, including underfloor heating (UFH) systems. The Vitodens 100-W requires a CombiPLUS A flow restrictor when used with certain configurations. Gas Council Numbers are 41-819-21, 41-819-22, 41-819-23, and 41-819-24.
Target Audience for this User Manual
This user manual is specifically designed for homeowners, heating engineers, and qualified technicians responsible for the installation, operation, maintenance, and servicing of the Viessmann Vitodens 100-W WB1B gas-fired condensing boiler within the United Kingdom. It provides comprehensive guidance for safe and efficient use.
Homeowners will find clear instructions on operating the boiler and understanding its controls. Heating engineers will benefit from detailed installation and servicing procedures, including information on gas supply requirements and ventilation. Technicians will find valuable resources for troubleshooting common issues and interpreting error codes. Familiarity with basic plumbing and heating principles is assumed, but the manual aims to be accessible to all relevant parties.
Document Revision Date (02/03/2026)
This version of the Viessmann Vitodens 100-W WB1B user manual reflects the latest updates and revisions as of February 3rd, 2026 (02/03/2026). It incorporates feedback from field installations, addresses known issues, and ensures compliance with current UK safety regulations and standards.
Users should always refer to this most recent edition for accurate and up-to-date information regarding the installation, operation, maintenance, and troubleshooting of their boiler. Previous versions may contain outdated information. The document number associated with this revision is 5592 584 GB, as referenced in available literature. Regularly checking for updates is recommended to maintain optimal performance and safety.
Safety Instructions
Always follow these safety instructions to prevent hazards during installation, operation, and maintenance of the Vitodens 100-W WB1B boiler.
General Safety Precautions
Prior to any work on the Vitodens 100-W WB1B, disconnect the boiler from the power supply. Installation and servicing must be performed by qualified and competent personnel, adhering to all relevant UK regulations.
Ensure adequate ventilation in the boiler room, as combustion requires air and produces exhaust gases. Never block or obstruct the flue. Regularly check for gas leaks using appropriate methods.
This appliance is not intended for use by persons (including children) with reduced physical, sensory or mental capabilities, or lack of experience and knowledge, unless supervised. Keep children away from the boiler.
Do not attempt to modify the boiler or use non-approved spare parts. Always refer to the official Viessmann documentation for guidance.
Warning Symbols and Their Meanings
The Vitodens 100-W WB1B utilizes several warning symbols to alert users to potential hazards. A triangle with an exclamation mark (!) indicates general warnings, requiring attention to possible risks. A flame symbol signifies a risk of fire or hot surfaces – avoid touching.
An electrical symbol (lightning bolt) warns of electric shock hazards; ensure the power is off before servicing. The ‘hot surface’ symbol indicates components may be dangerously hot during or immediately after operation.
Symbols relating to specific gases or fluids will be present where applicable, emphasizing the need for caution. Always consult the full user manual for a comprehensive explanation of each symbol and the corresponding safety measures.
Ignoring these warnings could result in personal injury, damage to the boiler, or unsafe operating conditions.
Carbon Monoxide Safety
Carbon Monoxide (CO) is a colorless, odorless, and highly poisonous gas produced by incomplete combustion. The Vitodens 100-W WB1B is designed to minimize CO production, but proper installation and maintenance are crucial. Ensure a functioning CO detector is installed in a central location near the boiler, following manufacturer’s instructions.
Regular servicing by a qualified Gas Safe registered engineer is essential to verify correct operation and identify any potential issues. Symptoms of CO poisoning include headache, dizziness, nausea, and confusion.
If a CO alarm sounds, immediately ventilate the area, evacuate all occupants, and contact the emergency services and a qualified engineer. Never ignore a CO alarm!
Boiler Components and Identification
This section details external and internal components of the Vitodens 100-W WB1B, including the control panel, for easy identification during maintenance.
External Boiler Components
The Vitodens 100-W WB1B features a robust external casing, providing protection for internal parts. Key external features include the flue outlet, essential for safe combustion gas expulsion, and the condensate connection, vital for draining acidic condensate produced during condensing operation.
The front panel houses the control unit, offering user interface for settings and diagnostics. External pipe connections are present for gas supply, water inlet/outlet, and heating circuit connections. A primary circulation pump may be externally mounted, depending on system configuration.
Inspect these components regularly for damage or leaks. The boiler’s dimensions and weight are important considerations for installation and accessibility. Refer to the technical specifications for precise measurements.
Internal Boiler Components
Internally, the Vitodens 100-W WB1B utilizes a high-performance heat exchanger, crucial for efficient heat transfer from combustion gases to the heating system. A modulating burner adjusts gas supply based on demand, optimizing efficiency. The gas valve regulates gas flow, ensuring safe and controlled combustion.
A fan facilitates airflow for combustion and flue gas extraction. The condensate trap collects acidic condensate, preventing corrosion. A pump circulates heating water throughout the system. Safety components, including pressure sensors and temperature sensors, monitor operation and prevent overheating.
These components work in harmony to deliver reliable and efficient heating. Regular servicing ensures optimal performance and longevity of these internal parts.
Control Panel Overview
The Vitodens 100-W WB1B’s control panel provides a user-friendly interface for managing heating and hot water. It displays current room temperature, set temperature, and operating mode. Buttons allow adjustment of temperature settings and selection between constant temperature or weather-compensated mode.
Error codes are displayed to indicate system faults, aiding troubleshooting. The panel also shows burner status and pump activity. Access to settings allows customization of heating schedules and other parameters.
Familiarizing yourself with the control panel is essential for efficient operation. Refer to the operating instructions for detailed explanations of each function and symbol displayed.
Installation Requirements (UK Specific)
UK installation demands adherence to gas supply regulations, proper ventilation, and correct condensate drain setup for optimal and safe boiler performance.
Gas Supply Requirements
The Vitodens 100-W WB1B is compatible with both natural gas and LPG, requiring appropriate gas council numbers (41-819-21 to 41-819-24). A qualified Gas Safe registered engineer must install and commission the boiler, ensuring the gas supply conforms to current UK regulations. The incoming gas supply pressure must fall within the specified range detailed in the technical specifications.
Pipe sizing is critical; it should be calculated according to the boiler’s output and the length of the gas pipe run to avoid pressure drop. A suitable gas isolation valve must be installed upstream of the boiler. Regular leak testing of all gas connections is essential for safety. Ensure the gas supply is free from contaminants that could damage the boiler components. Always consult the full installation instructions for detailed guidance.
Ventilation Requirements
Proper ventilation is crucial for safe operation of the Vitodens 100-W WB1B, ensuring adequate combustion air and preventing the build-up of harmful fumes. UK regulations dictate specific ventilation requirements depending on the boiler’s installation type – whether in a purpose-provided appliance room, a kitchen, or another enclosed space.
If installed in an appliance room, a permanent vent opening must be provided, sized according to BS 5871 Part 4:2008. Kitchen installations generally have sufficient natural ventilation, but this must be verified. Avoid obstructing ventilation openings. The flue system must be correctly installed to ensure safe exhaust of combustion products. Always refer to the full installation instructions for precise ventilation specifications.
Condensate Drain Installation
The Vitodens 100-W WB1B, as a condensing boiler, produces acidic condensate that requires safe disposal via a dedicated drain. UK building regulations stipulate specific requirements for condensate drain installation to prevent corrosion and ensure environmental protection. The drain must be constructed from a suitable material resistant to acidic condensate, such as PVC-U.
It should terminate with a visible air break, preventing back-siphonage. Avoid long horizontal runs and ensure the drain is adequately supported and protected from freezing. Connection to a suitable wastewater drain is essential; never connect to a potable water system. Always consult local water authority guidelines and the full installation instructions for detailed guidance.
Operating the Vitodens 100-W WB1B
The Vitodens 100-W WB1B operates in constant temperature or weather-compensated mode, providing heating and hot water as needed by the user.
Initial Start-Up Procedure
Before initial start-up, ensure the boiler is correctly installed according to UK regulations and the installation instructions. Verify the gas supply is connected and the condensate drain is properly installed.
Open the gas supply valve slowly and check for leaks using a suitable leak detection fluid. Power on the boiler using the mains power supply. The control unit will initiate a self-test sequence.
Follow the on-screen prompts to set the date, time, and initial heating parameters. Bleed the heating system to remove any trapped air. Monitor the boiler’s operation during the first few cycles to ensure correct functionality and check for any error messages.
Refer to the troubleshooting section if any issues arise during the start-up process.
Setting the Room Temperature
The Vitodens 100-W WB1B allows precise room temperature control via the control unit. To adjust the desired temperature, use the ‘+’ and ‘-’ buttons on the control panel. The current setpoint is displayed clearly on the screen.
In constant temperature mode, the boiler maintains the set temperature consistently. For weather-compensated mode, the temperature adjusts automatically based on external conditions, optimizing efficiency.
You can create heating schedules to automatically adjust temperatures throughout the day, saving energy. Explore the control unit’s menu to customize these schedules to your preferences.
Ensure thermostats connected to UFH zones are also set appropriately for optimal comfort and efficiency.
Hot Water Operation
The Vitodens 100-W WB1B efficiently provides domestic hot water on demand. When a hot water tap is opened, the boiler automatically modulates to deliver the required flow rate and temperature.
For systems with hot water storage tanks, the boiler heats the water within the tank, maintaining a consistent supply. The system can be configured to prioritize hot water production when demand is detected.
If connected to multiple heating circuits and a hot water cylinder coil, ensure the flow restrictor (CombiPLUS A) is correctly installed, as specified in the installation instructions.
Adjust the hot water temperature via the control unit to suit your preferences, balancing comfort and energy efficiency.
Control System and Settings
The Vitodens 100-W WB1B features a user-friendly control unit allowing operation in constant temperature or weather-compensated modes for optimal efficiency.
Understanding the Control Unit
The control unit is the central interface for operating your Viessmann Vitodens 100-W WB1B boiler. It allows you to monitor system status, adjust settings, and access diagnostic information. The unit displays crucial parameters like current room temperature, hot water temperature, and boiler operating mode.
Navigating the control unit involves using the buttons to access menus and modify settings. You can switch between constant temperature and weather-compensated operation. The display will also show any active error codes, providing a quick indication of potential issues. Refer to the detailed error code section within this manual for specific troubleshooting steps.
Understanding the symbols and indicators on the control panel is essential for efficient operation. The manual provides a comprehensive guide to interpreting these visual cues, ensuring you can effectively manage your heating system.
Weather-Compensated Mode Operation
Weather-compensated mode optimizes heating based on external temperature, maximizing efficiency and comfort. The Vitodens 100-W WB1B adjusts the boiler’s output to maintain a consistent indoor temperature, regardless of outdoor conditions. This is achieved by utilizing an external temperature sensor, which feeds data to the control unit.
In this mode, the boiler modulates its heat output, providing only the necessary energy to meet the heating demand. This reduces fuel consumption and minimizes temperature fluctuations. Setting the desired indoor temperature is key; the system then automatically adjusts to maintain it.
Proper configuration of the external temperature sensor is crucial for accurate weather compensation. Consult the installation instructions for correct placement and setup to ensure optimal performance and energy savings.
Constant Temperature Mode Operation
In constant temperature mode, the Vitodens 100-W WB1B maintains a pre-set water temperature in the heating system, regardless of external weather conditions. This mode is simpler than weather compensation, offering a consistent heating experience. The boiler cycles on and off to maintain the selected water temperature, suitable for systems without external sensors.
Users define a target water temperature via the control unit. The boiler then operates to achieve and sustain this temperature, providing heat to radiators or underfloor heating. While straightforward, this mode may be less efficient than weather compensation, particularly during milder weather.
For optimal performance, ensure the set temperature aligns with your comfort preferences and the system’s design parameters.
Maintenance and Servicing
Regular maintenance, including filter cleaning, is crucial for optimal performance. Annual servicing by a qualified engineer is also recommended for safety and efficiency.
Regular Maintenance Tasks
To ensure the longevity and efficient operation of your Viessmann Vitodens 100-W WB1B boiler, several regular maintenance tasks should be performed. These are primarily focused on maintaining clean components and optimal water flow. Visually inspect the boiler regularly for any signs of leaks or corrosion. Periodically check the condensate drain for blockages, as these can cause the boiler to shut down.
Crucially, the system filter requires routine cleaning to remove debris and prevent reduced heating performance. The frequency of filter cleaning will depend on the water quality in your area, but it’s advisable to check it at least annually. Refer to the ‘Filter Cleaning Procedures’ section for detailed instructions. Always ensure the boiler is switched off and cooled down before undertaking any maintenance work.
Filter Cleaning Procedures
Regularly cleaning the filter in your Viessmann Vitodens 100-W WB1B is vital for maintaining optimal performance. First, isolate the boiler’s power supply. Locate the filter – typically found on the return pipe. Carefully close the isolation valves either side of the filter. Place a suitable container beneath the filter to catch any escaping water.
Slowly unscrew the filter housing, releasing any trapped pressure. Remove the filter element and rinse it thoroughly under clean running water, removing all debris. Inspect the filter for damage and replace it if necessary. Reassemble the filter, ensuring a tight seal, and slowly reopen the isolation valves. Check for leaks and restore the boiler’s power supply.
Annual Servicing Requirements
To ensure the longevity and efficiency of your Viessmann Vitodens 100-W WB1B, annual servicing by a Gas Safe registered engineer is crucial. This service should include a comprehensive boiler inspection, checking for gas leaks and combustion efficiency. The engineer will verify the functionality of safety devices, such as the carbon monoxide detector.
They will also clean key components, including the burner and heat exchanger, and inspect the flue for blockages. Checking and adjusting the gas pressure is essential, alongside a review of the control system settings. Documentation of the service, including gas safety checks, must be provided. Adhering to these requirements maintains warranty validity and safe operation.
Troubleshooting Common Issues
This section addresses typical problems like boiler start-up failures, low water pressure, and error codes, offering guidance for UK Vitodens 100-W WB1B users.
Boiler Not Starting
If your Viessmann Vitodens 100-W WB1B fails to ignite, first check the gas supply is active and the boiler is receiving gas. Verify the main power switch is on and the control unit displays power. Examine the error code displayed – consult the ‘Error Codes and Their Meanings’ section for specific diagnostics.
Ensure the condensate drain isn’t blocked, as this can trigger a safety lockout. A low water pressure situation will also prevent ignition; check the system pressure gauge and repressurise if necessary (refer to installation instructions). If the issue persists, reset the boiler following the instructions in the control system section.
If repeated attempts fail, do not attempt self-repair. Contact a qualified Gas Safe registered engineer for assistance to avoid potential hazards and ensure correct diagnosis and repair.
Low Water Pressure
A low water pressure reading on your Viessmann Vitodens 100-W WB1B indicates insufficient water within the central heating system. This prevents proper operation and can trigger error codes. Locate the pressure gauge, typically on the front of the boiler, and note the reading. The ideal pressure is usually between 1 and 1.5 bar (check your system’s specific requirements).
To repressurise, locate the filling loop (often near the boiler). Carefully open both valves on the filling loop to allow water from the mains supply to enter the system. Monitor the pressure gauge and close the valves when the desired pressure is reached.
If pressure consistently drops, investigate for leaks in the system. Contact a qualified heating engineer if you are unable to resolve the issue or suspect a significant leak.
Error Codes and Their Meanings
The Viessmann Vitodens 100-W WB1B utilizes error codes to diagnose potential issues. These codes are displayed on the control panel, providing valuable information for troubleshooting. While a comprehensive list is found in the installation and service instructions, some common codes include those related to flame failure, low water pressure, or issues with the condensate drain.
For example, a flashing flame symbol may indicate a flame failure. A low-pressure warning will display a corresponding code. Always consult the full error code list in the official documentation to accurately identify the problem.
Attempting simple resets may resolve minor errors, but persistent codes require a qualified heating engineer’s attention. Do not attempt repairs yourself.
Technical Specifications
The Vitodens 100-W WB1B offers an output range of 7.9 to 26.0 kW and carries Gas Council Numbers: 41-819-21 to 41-819-24.
Output Range (7.9 to 26.0 kW)
The Viessmann Vitodens 100-W WB1B boiler is available in a range of outputs to suit varying heating demands within UK properties. This particular model series covers a capacity from a minimum of 7.9 kW up to a maximum of 26.0 kW. Selecting the appropriate output is crucial for optimal efficiency and comfort.
A lower output (7.9 kW) is generally suitable for smaller homes with fewer radiators or underfloor heating circuits, minimizing energy consumption. Conversely, a higher output (26.0 kW) is better suited for larger properties, those with greater heating demands, or homes with multiple bathrooms requiring simultaneous hot water supply.
Proper sizing ensures the boiler operates efficiently, avoiding short-cycling or struggling to meet heating needs. Consult a qualified heating engineer to determine the ideal output for your specific home and hot water requirements.
Gas Council Numbers (41-819-21, 41-819-22, 41-819-23, 41-819-24)
For identification and regulatory compliance within the UK, the Viessmann Vitodens 100-W WB1B boiler is assigned specific Gas Council Numbers. These numbers are essential for verifying the boiler’s approval and ensuring it meets UK safety standards.
The relevant Gas Council Numbers for this model are: 41-819-21, 41-819-22, 41-819-23, and 41-819-24. These numbers correspond to different variations within the 100-W WB1B series, potentially relating to gas type (natural gas or LPG) or output rating.
When contacting Gas Safe registered engineers or ordering replacement parts, providing the correct Gas Council Number is crucial for accurate service and compatibility. Always refer to the boiler’s rating plate for the specific number applicable to your unit.
Dimensions and Weight
Understanding the physical specifications of the Viessmann Vitodens 100-W WB1B is vital for proper installation and ensuring sufficient space allocation within the property. Accurate dimensions and weight are crucial for safe handling and mounting.
While specific dimensions vary slightly depending on the model’s output (7.9 to 26.0 kW), the 100-W WB1B is designed as a compact, wall-mounted unit. Detailed dimensional drawings are available in the accompanying installation instructions.
The approximate weight of the boiler will also depend on the specific model, but generally falls within a manageable range for a single installer or a small team. Always consult the technical data sheet for precise weight information before lifting or maneuvering the unit.