worcester greenstar heatslave 18/25 user manual
Category : United Kingdom
Worcester Greenstar Heatslave 18/25 User Manual: An Overview
This manual provides essential guidance for operating and maintaining your Worcester Greenstar Heatslave 18/25 boiler. It covers safety, operation, troubleshooting, and servicing details.
The Worcester Greenstar Heatslave 18/25 is a highly efficient, wall-mounted condensing boiler designed for central heating and domestic hot water; This boiler series, available in 18kW and 25kW outputs, offers reliable performance and is suitable for a range of home sizes.
This manual is specifically tailored for the Heatslave 18/25 models. It’s crucial to only use these instructions with the stated appliance models, as applying them to other boilers could be dangerous. The information within applies to installations within the UK and Eire, adhering to statutory obligations. Understanding its features and following these guidelines will ensure safe and optimal operation, maximizing efficiency and longevity.
Scope of this Manual
This user manual comprehensively covers the Worcester Greenstar Heatslave 18/25 boiler, providing detailed instructions for users and qualified service engineers. It includes sections on boiler components, safety precautions, operating procedures, and troubleshooting common issues.
You’ll find guidance on interpreting error codes, performing regular maintenance like filter cleaning, and understanding annual servicing requirements. The manual also offers a brief overview of installation and commissioning procedures, though these should ideally be carried out by a certified professional. Access to downloadable PDF versions and online support resources are also detailed, ensuring readily available assistance.

Understanding Your Boiler
This section details the core components of the Greenstar Heatslave 18/25, explaining their functions and how they contribute to efficient heating and hot water delivery.
Boiler Components and Their Functions
The Greenstar Heatslave 18/25 comprises several key components working in harmony. The heat exchanger efficiently transfers heat to the water. A modulating fan adjusts the gas supply for optimal combustion. The pump circulates hot water throughout your heating system.
Crucially, the PCB (Printed Circuit Board) controls all boiler functions, ensuring safe and efficient operation. A gas valve regulates gas flow, while the diverter valve directs flow between heating and hot water. The condensate trap collects acidic condensate, and a pressure relief valve safeguards against overpressure.
Understanding these components aids in diagnosing potential issues and appreciating the boiler’s overall functionality. Regular maintenance, as outlined later, ensures each part operates effectively.
Safety Precautions
Prioritize safety when operating your Greenstar Heatslave 18/25 boiler. Never attempt repairs yourself; always contact a qualified, Gas Safe registered engineer. Ensure adequate ventilation in the boiler room to prevent carbon monoxide buildup. Regularly check for gas leaks – a gas smell requires immediate action: open windows and call the gas emergency service.
Do not obstruct the boiler’s ventilation openings. Keep flammable materials away from the appliance. Supervise children and vulnerable individuals around the boiler. Be aware of hot surfaces and pipes to avoid burns.
Always follow the instructions in this manual and heed any warning labels on the boiler itself. Ignoring these precautions could lead to serious injury or property damage.
Boiler Specifications (18/25 Models)
The Greenstar Heatslave 18/25 models are combi boilers designed for central heating and domestic hot water. The 18 model offers a maximum heat output of 18kW, while the 25 model provides 25kW. Both feature a compact design suitable for various installation locations.
Gas input rates vary between the models, influencing gas consumption. These boilers are designed for natural gas, and conversion kits may be available for LPG. Hot water flow rates differ; the 25kW model delivers a higher flow rate for faster filling of baths.
These specifications apply specifically to units sold in the UK and Eire, adhering to regional standards and regulations.

Operating Instructions
Follow these instructions to safely and efficiently operate your Greenstar Heatslave 18/25 boiler. Proper use ensures optimal performance and longevity of the appliance.
Switching the Boiler On and Off
To switch on your Greenstar Heatslave 18/25 boiler, ensure the gas supply is active and the boiler’s isolation switch is in the ‘on’ position. The power switch, typically located on the front panel, should then be turned to ‘I’ or ‘On’. Allow a short period for the boiler to initiate its start-up sequence.

For shutdown, reverse the process. Turn the power switch to ‘O’ or ‘Off’. It’s crucial not to switch off the gas supply directly unless maintenance is required. Always allow the boiler to cool down before any servicing or prolonged periods of inactivity. Remember to consult the full manual for detailed procedures and safety guidelines.
Setting the Temperature
Adjusting the temperature on your Greenstar Heatslave 18/25 is typically done via the control panel. Use the up and down arrow buttons to select your desired heating temperature. The current setpoint is displayed on the boiler’s screen. For hot water, a separate control may exist, allowing independent temperature adjustment.
Consider energy efficiency when setting temperatures. Lowering the thermostat by just one degree can significantly reduce energy consumption. Familiarize yourself with the boiler’s programmable features for customized heating schedules. Always refer to the complete user manual for specific instructions and optimal settings for your home.
Understanding the Boiler Display Panel
The Greenstar Heatslave 18/25 display panel provides crucial information about your boiler’s status. Key indicators include the current heating temperature, hot water status, and any active error codes. A flame icon signifies the burner is active, while other symbols indicate system pressure or operational mode.
Familiarize yourself with these indicators to quickly assess the boiler’s performance. Error codes require referencing the troubleshooting section of the manual for diagnosis. The display also shows time and date if programmed. Regularly checking the display helps ensure optimal operation and allows for prompt identification of potential issues.
Hot Water Control
The Greenstar Heatslave 18/25 offers adjustable hot water settings, allowing you to customize temperature and flow. Typically, hot water is activated via a demand from a tap or shower. The boiler responds by heating water as needed, maintaining your selected temperature.
Some models may feature pre-heat modes for faster hot water delivery. Adjusting the hot water temperature is usually done through the boiler’s control panel. Ensure the temperature is set safely to prevent scalding, especially for households with children or vulnerable individuals. Proper hot water control optimizes comfort and energy efficiency.

Troubleshooting Common Issues
This section details solutions for typical problems, including ignition failures, low pressure, error codes, and frozen condensate pipes, ensuring efficient boiler operation.
Boiler Not Igniting
If your Greenstar Heatslave 18/25 fails to ignite, several factors could be at play. First, verify the gas supply is active and reaching the boiler; check other gas appliances.
Secondly, ensure the boiler has power and the display panel isn’t showing a lock-out error. A lock-out usually requires a reset – consult the error code section.
Check that the condensate pipe isn’t frozen, especially during colder months, as this can prevent ignition. If the issue persists, it could indicate a problem with the ignition components, such as the ignition transformer or flame detection sensor. In such cases, contact a qualified Worcester Bosch engineer for assistance; do not attempt repairs yourself.
Low Pressure Issues
Experiencing low pressure on your Greenstar Heatslave 18/25 boiler can disrupt heating and hot water. Initially, check the boiler’s pressure gauge – it should ideally be between 1 and 1.5 bar.
Low pressure often stems from a leak within the central heating system. Inspect radiators for leaks, along with all visible pipework and connections.
If no leaks are apparent, you may need to repressurise the boiler. Consult the ‘Operating Instructions’ section for the correct procedure. Repeatedly low pressure indicates a leak that requires professional attention. Do not ignore this issue, as it can lead to boiler damage. Contact a qualified engineer for diagnosis and repair.
Error Codes and Their Meanings
Your Worcester Greenstar Heatslave 18/25 boiler utilizes error codes to signal potential faults. These codes appear on the boiler’s display panel, providing a quick diagnostic tool.
While a comprehensive list is within the official PDF manual, common codes indicate issues like flame failure, low water pressure, or problems with the gas supply.
Do not attempt to repair the boiler yourself based solely on the error code. Refer to the manual for the specific code’s meaning and recommended action. Often, resetting the boiler may temporarily resolve minor issues, but persistent codes necessitate a qualified engineer’s inspection; Ignoring error codes can lead to further damage.
Frozen Condensate Pipe
During cold weather, the condensate pipe of your Greenstar Heatslave 18/25 can freeze, causing water to back up and potentially shut down the boiler. This pipe expels acidic condensate produced during combustion.
If you suspect a frozen pipe, do not attempt to thaw it with direct heat. Instead, ensure the surrounding area is well-ventilated and allow it to thaw naturally.
Pouring warm (not boiling!) water over the pipe may help, but proceed cautiously. Persistent freezing indicates insulation may be needed. Contact a qualified engineer if the issue recurs, as a blocked or damaged pipe requires professional attention.

Maintenance and Servicing
Regular maintenance, including filter cleaning, is crucial for optimal performance. Annual servicing by a qualified engineer is also highly recommended for longevity.
Regular Maintenance Tasks
To ensure your Greenstar Heatslave 18/25 operates efficiently and reliably, perform these routine checks. Visually inspect the boiler regularly for any leaks or unusual noises. Keep the boiler casing clean and free from obstructions to allow for proper ventilation.
Periodically check the condensate pipe for blockages, especially during colder months, to prevent issues. Familiarize yourself with the location of the filter and understand the cleaning procedures outlined in the full manual.
These simple tasks, performed consistently, can significantly reduce the risk of breakdowns and extend the lifespan of your boiler. Remember, these are supplementary to the annual servicing performed by a qualified engineer.
Annual Servicing Requirements
Worcester Bosch Group strongly recommends annual servicing by a qualified, Gas Safe registered engineer. This comprehensive service includes a thorough inspection of all key components, ensuring optimal performance and safety. The engineer will check gas pressure, flue integrity, and combustion efficiency.
Servicing also involves cleaning vital parts, identifying potential issues before they escalate, and verifying the boiler’s operation against manufacturer specifications.
Maintaining a regular service history is crucial for warranty validity and peace of mind. Contact a Worcester Bosch Group contact centre to arrange a service or explore available service contracts.
Filter Cleaning Procedures
Regular filter cleaning is vital for maintaining boiler efficiency and preventing operational issues. The Greenstar Heatslave 18/25 features filters that require periodic attention to remove debris and ensure unrestricted water flow. Consult the full user manual for detailed, step-by-step instructions specific to your model.
Typically, this involves isolating the boiler, locating the filter assembly, and carefully removing and cleaning the filter element under running water.
Re-installation must be performed correctly to avoid leaks or reduced performance. If unsure, always consult a qualified engineer.

Technical Information
This section details crucial specifications, including boiler dimensions, weight, gas connection requirements, and necessary water pressure levels for optimal performance.
Boiler Dimensions and Weight
Understanding the physical characteristics of your Greenstar Heatslave 18/25 is vital for installation and ensuring adequate space allocation. Precise dimensions are crucial when integrating the boiler into your home’s heating system. While specific measurements can vary slightly depending on the exact model iteration, generally, these boilers are designed to be relatively compact for ease of installation in various locations.
The weight of the unit is also an important consideration, particularly during installation, as it impacts the necessary support structures and handling procedures. Accurate weight information ensures safe and secure mounting. Refer to the official installation and servicing instructions for the precise dimensions and weight specifications applicable to your specific Greenstar Heatslave 18/25 model.
Gas Connection Details
Proper gas connection is paramount for the safe and efficient operation of your Worcester Greenstar Heatslave 18/25 boiler. This work MUST be carried out by a qualified and Gas Safe registered engineer. The boiler is designed to operate with specific gas types and pressures, detailed in the technical specifications section of the official manual.
Incorrect gas connection can lead to hazardous situations, including gas leaks and carbon monoxide poisoning. The gas supply pipe must adhere to all relevant regulations and standards. Ensure the engineer verifies the gas supply pressure and flow rate before commissioning the boiler. Always consult the official installation and servicing instructions for precise gas connection requirements specific to your model.
Water Pressure Requirements
Maintaining correct water pressure is crucial for optimal performance of your Worcester Greenstar Heatslave 18/25 boiler. Low water pressure can prevent the boiler from functioning correctly, while excessively high pressure can cause damage. The recommended static water pressure range is typically between 1.0 and 8.0 bar (14.5 – 116 psi), but always refer to the official manual for precise values.
Regularly check the boiler’s pressure gauge, located on the front panel. If the pressure is too low, you may need to re-pressurise the system following the instructions in the user manual. Do not attempt to adjust the pressure if you are unsure of the procedure; consult a qualified heating engineer.

Installation and Commissioning (Brief Overview)
Initial setup requires checks of gas supply and system integrity. Qualified engineers must verify proper functionality and safety before commissioning the Greenstar Heatslave 18/25.
Initial Setup Checks
Before first use, a qualified engineer must perform crucial initial setup checks. These include verifying the correct gas supply pressure and ensuring all gas connections are tight and leak-free.
The system’s water pressure should be checked and adjusted to the manufacturer’s recommended level.
Inspect all pipework for any damage or obstructions. Confirm the flue is correctly installed and unobstructed to ensure safe combustion.
Electrical connections must be verified for correct voltage and secure connections. Finally, the engineer will confirm the boiler’s control panel is functioning correctly and all safety devices are operational before commissioning.
Gas Supply Verification
A qualified Gas Safe registered engineer must verify the gas supply before commissioning. This involves checking the gas type matches the boiler’s rating – Natural Gas or LPG.
The incoming gas pressure must be within the specified range detailed in the boiler’s technical specifications.
All gas pipework should be thoroughly tested for leaks using a suitable leak detection fluid; never use a flame.
The engineer will confirm the gas valve is operating correctly and the gas flow rate is appropriate for the boiler’s output. Proper gas supply verification is critical for safe and efficient operation.

User Manual Resources
Access official PDF manuals online, explore FAQs, and connect with Worcester Bosch Group support for assistance. These resources aid boiler operation and maintenance.
Downloading the Official PDF Manual
Obtaining the official PDF manual for your Worcester Greenstar Heatslave 18/25 boiler is straightforward. This digital version provides comprehensive information at your fingertips, accessible on various devices. You can typically find the manual on the Worcester Bosch Group’s official website, often within their support or downloads section.
Searching for “Worcester Greenstar Heatslave 18/25 manual PDF” online will also yield direct links to downloadable files. Ensure the source is reputable to avoid potentially harmful downloads. The PDF includes detailed instructions, safety precautions, troubleshooting guides, and technical specifications, offering a complete resource for boiler owners and service professionals alike. Having this manual readily available ensures proper operation and maintenance of your heating system.
Accessing Online Support and FAQs
Worcester Bosch Group offers extensive online support resources for the Greenstar Heatslave 18/25 boiler. Their official website features a dedicated support section with frequently asked questions (FAQs) addressing common issues and concerns. This is a valuable first step for quick solutions to everyday problems.
Beyond FAQs, many websites provide forums and online communities where users share experiences and troubleshooting tips. Worcester Bosch also often provides interactive guides and video tutorials demonstrating key maintenance tasks. Utilizing these online resources can often resolve minor issues without needing to contact a service engineer, saving both time and expense. Remember to always prioritize safety and consult a professional when dealing with complex boiler issues.
Contacting Worcester Bosch Group Support
For issues requiring direct assistance, Worcester Bosch Group provides multiple contact channels. The user manual directs users to contact a Worcester Bosch Group contact centre for servicing needs. Details for reaching these centres are typically found inside the front cover of the physical manual.
Alternatively, their official website lists contact numbers for technical support, customer service, and sales inquiries. They also offer options for requesting a callback, ensuring a convenient way to connect with a representative. When contacting support, have your boiler model number (Greenstar Heatslave 18/25) and any relevant error codes readily available to expedite the process.

Important Notices
This manual’s instructions are specifically for the Worcester Greenstar Heatslave 18/25 models within the UK and Eire, adhering to regional regulations and warranty terms.
Warranty Information
Your Worcester Greenstar Heatslave 18/25 boiler is covered by a standard manufacturer’s warranty, the specifics of which depend on the date of installation and registration. Generally, a core warranty period applies to the boiler’s main components, offering peace of mind against manufacturing defects;
Extended warranties and service packages are also available, providing comprehensive coverage for parts and labor beyond the standard term. Registration of your boiler is crucial to validate the warranty and access support services. Keep your proof of purchase and installation details readily available.
The warranty does not cover issues arising from incorrect installation, improper use, scale buildup, or failure to adhere to the recommended servicing schedule. Refer to the full warranty document for complete terms and conditions.
Applicable Regions (UK and Eire)
This Worcester Greenstar Heatslave 18/25 user manual and its associated instructions are specifically tailored for use within the United Kingdom and the Republic of Ireland (Eire). The guidelines and safety recommendations detailed herein adhere to the relevant regulations and standards applicable in these regions.
Installation, servicing, and repairs should always be carried out by qualified and competent engineers registered with the appropriate governing bodies in either the UK or Eire. Using this manual outside of these regions may result in non-compliance with local regulations and potentially compromise the safe operation of the boiler.
Always ensure adherence to local gas safety regulations and building codes when installing or maintaining this appliance within the UK or Eire.
















































































