Instruction Manual for Baxi Combi 105E/105HE 16-Plate Hot Water Heat Exchanger

1. Introduction

This manual provides comprehensive instructions for the proper installation, operation, and maintenance of the 16-plate hot water heat exchanger, designed as a compatible replacement part for Baxi Combi 105E and 105HE boiler models. Adhering to these guidelines will ensure the safe, efficient, and prolonged performance of your heating system's hot water production.

The heat exchanger is a critical component responsible for transferring heat from the boiler's primary circuit to the domestic hot water supply, ensuring a consistent and reliable flow of hot water for your household needs.

2. Safety Information

WARNING: Installation and servicing of this heat exchanger must only be performed by a qualified and competent person, such as a Gas Safe registered engineer in the UK, or equivalent certified professional in other regions. Failure to comply can result in serious injury, property damage, or death.

• Always isolate the boiler from the main electrical supply and turn off the gas supply before commencing any work.
• Ensure the boiler and associated pipework are completely depressurized and drained before removing or installing the heat exchanger.
• Wear appropriate personal protective equipment (PPE), including gloves and eye protection, during installation and maintenance.
• Handle the heat exchanger carefully to avoid damage to its plates or connections.
• Check for leaks thoroughly after re-pressurizing the system.
• Dispose of old components responsibly and in accordance with local regulations.

3. Setup and Installation

This heat exchanger is designed for direct replacement in Baxi Combi 105E and 105HE boilers. It comes supplied with the necessary seals and screws for installation.

3.1 Pre-Installation Checks

• Verify that the new heat exchanger (Model 248048) is the correct part for your specific Baxi boiler model (105E or 105HE).
• Inspect the new heat exchanger for any signs of transit damage.
• Ensure all supplied components, including seals (O-rings) and screws, are present.

3.2 Installation Steps (Professional Installation Recommended)

1. Isolate and Drain: Turn off the boiler's electrical supply and gas supply. Drain the boiler and heating system completely.
2. Access Heat Exchanger: Refer to your specific Baxi Combi 105E or 105HE boiler manual for instructions on how to safely access the existing plate heat exchanger. This typically involves removing the boiler casing and potentially other components.
3. Remove Old Heat Exchanger: Carefully disconnect the pipework connections and remove the retaining screws or clips holding the old heat exchanger in place. Note the orientation for correct installation of the new part.
4. Clean Mounting Area: Thoroughly clean the mounting surfaces on the boiler where the heat exchanger sits, ensuring no debris or old gasket material remains.
5. Install New Heat Exchanger:
   

   Figure 3.2.1: The 16-plate heat exchanger with accompanying seals and screws.

   Position the new heat exchanger, ensuring the correct orientation. Apply the new O-rings (seals) to the connections as supplied. Secure the heat exchanger using the new screws provided. Ensure a snug fit without overtightening.

   

   Figure 3.2.2: Side profile of the heat exchanger, highlighting the plate design and included accessories.
   

   Figure 3.2.3: Alternate side view of the heat exchanger, showing the corrugated plates and included accessories.

   

   Figure 3.2.4: Top view of the heat exchanger, illustrating the connection points and the included seals and screws.

6. Reconnect Pipework: Reconnect all pipework to the heat exchanger, ensuring all connections are secure.
7. Refill and Re-pressurize: Refill the boiler and heating system with water and re-pressurize to the manufacturer's recommended level.
8. Check for Leaks: Carefully inspect all connections for any signs of water leaks. Rectify any leaks immediately.
9. Restore Power and Gas: Once satisfied there are no leaks, restore the electrical and gas supplies to the boiler.
10. Test Operation: Test the boiler's hot water function to ensure the new heat exchanger is operating correctly and providing consistent hot water.

4. Operating Principles

The 16-plate heat exchanger facilitates the transfer of thermal energy from the boiler's sealed central heating circuit to the domestic cold water supply, producing instantaneous hot water. Hot water from the primary circuit flows through alternate plates, while cold mains water flows through the other set of plates in a counter-flow arrangement. The large surface area provided by the multiple plates allows for efficient heat transfer without mixing the two water streams.

When a hot water tap is opened, a flow sensor in the boiler detects the demand, activating the diverter valve to direct primary hot water through the heat exchanger. This process ensures that hot water is available on demand, without the need for a hot water storage cylinder.

5. Maintenance

Regular maintenance of your boiler, including the heat exchanger, is crucial for its longevity and efficient operation. It is recommended that a qualified engineer services your boiler annually.

• Annual Inspection: During the annual boiler service, the engineer should inspect the heat exchanger for signs of scaling, corrosion, or blockages.
• Descaling: In hard water areas, limescale can build up within the heat exchanger plates, reducing efficiency and hot water flow. A qualified engineer can perform a chemical descaling procedure to remove these deposits.
• Leak Checks: Periodically check around the heat exchanger for any signs of water leaks or dampness. Address any leaks promptly to prevent further damage.
• System Flushing: Ensure the central heating system is flushed periodically to remove sludge and debris that could contaminate the primary side of the heat exchanger.

6. Troubleshooting

If you experience issues with your hot water supply, the heat exchanger may be a contributing factor. Always consult a qualified heating engineer for diagnosis and repair.

For any issues, always refer to your main Baxi boiler manual and contact a certified heating engineer.

7. Specifications

8. Warranty and Support

8.1 Warranty Information

This product typically comes with a 1-Year Warranty from the date of purchase. Please retain your proof of purchase for any warranty claims. The warranty covers manufacturing defects but does not cover damage caused by improper installation, misuse, neglect, or normal wear and tear, including limescale buildup.

8.2 Technical Support

For technical assistance, troubleshooting beyond this manual, or warranty claims, please contact your original supplier or a qualified heating engineer. Always provide your product model number (248048) and boiler model (Baxi Combi 105E/105HE) when seeking support.

It is strongly advised not to attempt repairs yourself if you are not a qualified professional.