Contents

Dear Customer,
Contents
- 9 Settings 53
- 10 Maintenance 62
- 11 Troubleshooting. 72
- 12 Decommissioning 77
- 13 Disposal 78
1 Safety
- 1.1
  - 1.1.1 Building Regulations and the Benchmark Commissioning Checklist
  - 1.1.2 The Benchmark Scheme
  - 1.1.3 Installer Notification Guidelines
- 1.2 General safety instructions
- 1.3 Recommendations
  - Important
  - Note
- 1.4 Specific safety instructions
  - 1.4.1 Handling
    - General
    - Preparation
    - Technique
    - Remember
- 1.5 Liabilities
  - 1.5.1 Manufacturer's liability
  - 1.5.2 Installer's liability
  - 1.5.3 User's liability
2 About this manual
- 2.1 General
- 2.2 Additional documentation
- 2.3 Symbols used
  - 2.3.1 Symbols used in the manual
    - Important
- 2.4 Abbreviations/Glossary
  - BS CH DHW GB
  - Hi Hs IE PCU
3 Technical specifications
- 3.1 Homologations
  - 3.1.1 Safety, Performance & Quality
  - 3.1.2 Certifications
  - 3.1.3 Gas category
  - 3.1.4 Standards
    - Codes of Practice refer to the most recent
- 3.2 Technical data
  - 3.2.1 Technical information
  - 3.2.2 Features of the temperature sensors
- 3.3 Dimensions and connections
- Electrical diagram
4 Description of the product
- 4.1 General description
- 4.2 Operating principle
  - 4.2.1 Air-gas adjustment
  - 4.2.2 Combustion
  - 4.2.3 Heating and domestic hot water production
- 4.3 MAIN COMPONENTS
  - 4.2.4 Schematic diagram
- 4.4 Control panel description
  - 4.4.1 Description of the control panel
- 4.5 Contents of the package
- 4.6 Accessories & options
5 Before installation
- 5.1 Installation standards and rules
- 5.2 Installation requirements
  - 5.2.1 Gas supply
  - 5.2.2 Electrical supply
    - The boiler must be connected to the mains fused 3A 230V 50HZ supply & control system using cable of 3 core 0.75mm 3183Y multi strand flexible type.
    - Important
  - 5.2.3 Hard water area
  - 5.2.4 Bypass
  - 5.2.5 System control
  - 5.2.6 Treatment of water circulating systems
  - 5.2.7 Showers
  - 5.2.8 Expansion vessel (CH only)
- 5.3 Flow rate/head at the plate characteristics
- 5.4 Choice of the location
  - 5.4.1 Location of the boiler
  - 5.4.2 Bath and shower rooms
    - Important
  - 5.4.3 Ventilation
  - 5.4.4 Condensate drain
    - It is strongly recommended to discharge internally into the household drainage system. If connecting to a rain water drain, that drain MUST dis charge into a foul drain.
    - Important
  - 5.4.5 Clearances
  - 5.4.6 Flue/chimney location
    - Important
    - Important
    - Important
    - 2
    - Important
    - Important
  - 5.4.7 Horizontal flue/chimney systems
    - Total equivalent length = A+B+C+2x90 bends
    - Important
    - See
  - 5.4.8 Flue/chimney trim
  - 5.4.9 Terminal guard
    - 1 ENSURE THAT NO PART OF THE WHITE OUTER CHIMNEY DUCT IS VISIBLE.
    - Important
  - 5.4.10 Flue/chimney deflector
  - 5.4.11 Flue/chimney accessories
    - See
  - 5.4.12 Data plate and boiler service label
- 5.5 Transport
- 5.6 Unpacking & initial preparation
  - 5.6.1 Unpacking
    - To unpack the boiler:
    - Important
    - Important
  - 5.6.2 Initial preparation
- 5.7 Connecting diagrams
  - 5.7.1 Filling information
  - 5.7.2 Domestic hot water circuit
    - Important
6 Installation
- 6.1 General
- 6.2 Assembly
  - 6.2.1 Fitting the pressure relief discharge pipe
    - Important
  - 6.2.2 Connecting the condensate drain
    - See
    - See
- 6.3 Air supply/flue gas connections
  - 6.3.1 Connecting the flue/chimney
    - Important
    - 1 4 2
    - 4
    - 2 5 5
    - Important
- 6.4 Electrical connections
  - 6.4.1 Accessing the electrical connections
    - See
    - Important
  - 6.4.2 Connecting the room thermostat
    - Important
  - 6.4.3 Service connection (SERVICE)
  - 6.4.4 Connecting on wall outdoor sensor
  - 6.4.5 Connecting the outside sensor (OS)
    - Important
  - 6.4.6 Identifying label
    - Important
- 6.5 Filling the installation
  - 6.5.1 Flushing the system
  - 6.5.2 Fill the installation
    - Important
  - 6.5.3 Filling the condensate trap
- 6.6 Draining the installation
7 Commissioning
- 7.1 General
- 7.3 Commissioning procedure
  - Important
- 7.4 Gas settings
  - 7.4.1 Check the operational (working gas inlet pressure and
    - Note
    - See
  - 7.4.2 Combustion parameters
  - Activating the chimney sweep function
    - Important
  - 7.4.3 Service settings
  - 7.4.4 Calibrating the gas valve
    - Important
    - Important
- 7.5 Final instructions
  - 7.5.1 Handover
    - Important
8 Operation
- 8.1 Use of the control panel
  - 8.1.1 Browsing the menus
    - Important
  - 8.1.2 Running the automatic detection function
  - 8.1.3 Information menu display
- 8.2 Start-up
  - 8.2.1 Procedure for first start-up
  - 8.2.2 Changing the heating flow temperature
    - Important
    - Important
  - 8.2.3 Changing the domestic hot water (DHW) temperature
- 8.3 Shutdown
  - 8.3.1 Switching off the heating and domestic hot water (DHW)
    - Important
    - Important
    - Important
- 8.4 Degassing function
- 8.5 Frost protection
  - Important
9 Settings
- 9.1 Accessing the settings
- 9.2 List of parameters
  - Important
  - 9.2.1 Resetting factory settings
- 9.3 Setting the parameters
  - 9.3.1 Setting the heating curve
    - Important
    - Important
    - See
    - Important
    - Note
    - Important
- 9.4 Reading out measured values
  - 9.4.1 Statuses and sub-statuses
- 9.5 Reading meters
10 Maintenance
- Important
- Check the Combustion Performance (CO/CO2 ratio) Set the boiler to operate at maximum rate.
- 10.2.1 Service notification
  - Important
  - Important
  - Important
- 10.2.2 Resetting the displayed maintenance message
  - Important
- 10.2.3 Resetting the upcoming maintenance message
- 10.3 Standard inspection and maintenance operations
  - 10.3.1 Annual Servicing
    - Important
  - 10.3.2 Checking the water pressure
  - 10.3.3 Checking the expansion vessel
  - 10.3.4 Checking the flue gas discharge and the air supply
  - 10.3.5 Checking the combustion
  - 10.3.6 Checking the automatic air vent
  - 10.3.7 Cleaning the siphon
  - 10.3.8 Electrode distances
  - 10.3.9 Checking the burner and cleaning the heat exchanger
  - 10.3.10 Water unit
  - 10.3.11 Cleaning/replacing the DHW filter
  - 10.3.12 Removing limescale
    - For more information, see
- 10.4 Specific maintenance operations
  - 10.4.1 Detection/ignition electrode replacement
  - 10.4.2 Dismantling the water-water exchanger
  - 10.4.3 Replacing flow and return sensors
  - 10.4.4 Replacing the return valve
  - 10.4.5 Replacing the 3-way valve
  - 10.4.6 Replacing the pressure sensor
  - 10.4.7 Hall effect sensor
  - 10.4.8 Safety pressure relief valve
  - 10.4.9 Diverter valve motor
  - 10.4.10 Pump - replacement
  - 10.4.11 Replacing the expansion vessel
  - 10.4.12 Replacing the PCB
11 Troubleshooting
- 11.1 Temporary and permanent faults
  - TEMPORARY FAULT (A/H.x.x.)
  - PERMANENT FAULT (E.x.x)
  - Important
12 Decommissioning
- 12.1 Disassembly
- 12.2 Recommissioning
13 Disposal
- 13.1 Disposal and recycling

Baxi 424 Combi 2 Installation and Service Manual

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Baxi 424 Combi 2 Specification

The Baxi 424 Combi 2 is a highly efficient and compact combination boiler designed for residential use. It features a 24 kW output, making it suitable for small to medium-sized homes. The boiler is engineered for ease of installation and maintenance, with a lightweight design that simplifies handling. It integrates a stainless steel heat exchanger, which enhances durability and heat transfer efficiency. The boiler operates with an impressive ErP A rating for both heating and hot water, ensuring energy-efficient performance. It supports a flow rate of up to 10 liters per minute, providing a reliable supply of hot water on demand. Advanced electronic controls allow for precise temperature management, and the unit is compatible with a range of smart thermostat systems, enabling users to optimize heating schedules and reduce energy consumption. The Baxi 424 Combi 2 incorporates an intuitive front-mounted control panel with a digital display, offering easy access to settings and diagnostics. Safety features include automatic shutdown in the event of a malfunction, frost protection, and built-in pressure relief. The boiler operates quietly, minimizing disruption in residential environments. It is compatible with natural gas and can be adapted for LPG use with a conversion kit. The compact dimensions of the Baxi 424 Combi 2 facilitate installation in confined spaces, such as kitchen cupboards, without compromising functionality. The boiler is backed by a robust warranty, reflecting Baxi's commitment to quality and customer satisfaction. Overall, the Baxi 424 Combi 2 combines reliability, efficiency, and user-friendly operation, making it an excellent choice for homeowners seeking a cost-effective and dependable heating solution.

Baxi 424 Combi 2 F.A.Q.

How do I reset the Baxi 424 Combi 2 boiler?

To reset your Baxi 424 Combi 2 boiler, press and hold the reset button for at least 5 seconds. The button can be found on the front panel of the boiler. Release the button and wait for the boiler to restart.

What should I do if my Baxi 424 Combi 2 boiler is not igniting?

First, check that the gas supply is turned on and there is no disruption in service. Ensure that the thermostat is set to the desired temperature and the boiler is receiving power. If the issue persists, consult a qualified engineer.

How often should I service my Baxi 424 Combi 2 boiler?

It is recommended to service your Baxi 424 Combi 2 boiler annually by a qualified engineer to ensure it operates efficiently and safely.

What does the error code E133 mean on the Baxi 424 Combi 2?

Error code E133 indicates a failure to ignite. This could be due to a problem with the gas supply, ignition, or flame detection. Check the gas supply and reset the boiler. Contact a professional if the issue persists.

How can I increase the water pressure in my Baxi 424 Combi 2 boiler?

Locate the filling loop, which is usually a silver, flexible hose beneath the boiler. Open the valves on the filling loop to allow water to enter the system, watching the pressure gauge until it reaches the recommended level (usually 1-1.5 bar). Close the valves once done.

Why is my Baxi 424 Combi 2 boiler making a banging noise?

A banging noise can indicate kettling, which is caused by a build-up of limescale or sludge. It is advisable to have a professional powerflush the system to remove any blockages.

What is the correct operating pressure for a Baxi 424 Combi 2 boiler?

The correct operating pressure for the Baxi 424 Combi 2 boiler is typically between 1 and 1.5 bar when the system is cold.

How do I bleed radiators in a system with a Baxi 424 Combi 2 boiler?

Turn off the heating system and use a radiator key to open the valve at the top of each radiator. Allow air to escape until water begins to leak out, then close the valve. Check the boiler pressure afterward and top it up if necessary.

What should I do if my Baxi 424 Combi 2 boiler is leaking water?

Turn off the water supply and the boiler. Check for leaks around pipes and seals. Contact a qualified engineer to identify and fix the source of the leak.

Can I use a smart thermostat with my Baxi 424 Combi 2 boiler?

Yes, the Baxi 424 Combi 2 boiler is compatible with most smart thermostats. Consult your thermostat's manual for installation instructions or hire a professional to ensure correct setup.