Baxi Combi 24 HE Installation & Service Instructions Manual
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Baxi Combi 24 HE Installation & Service Instructions Manual

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Installation & Service Instructions
Combi 24 HE
This is a Wall Mounted Powered Flue Condensing Combination Boiler Gas Fired
Central Heating Unit.
The boiler meets the requirements of Statutory Instrument " The Boiler (Efficiency)
Regulations 1993 N
o
3083" and is deemed to meet the requirements of Directive
92/42/EEC on the energy efficiency requirements for new hot water boilers fired
with liquid or gaseous fuels:-
Type test for purpose of Regulation 5 certified by:
Notified Body 0051.
Product/Production certified by:
Notified Body 0086.
For use in GB/IE only.
These instructions include the Benchmark Commissioning Checklist and should be
left with the User for safe keeping.

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  • Page 1 Installation & Service Instructions Combi 24 HE This is a Wall Mounted Powered Flue Condensing Combination Boiler Gas Fired Central Heating Unit. The boiler meets the requirements of Statutory Instrument “ The Boiler (Efficiency) Regulations 1993 N 3083” and is deemed to meet the requirements of Directive...

  • Page 2: Table Of Contents

    Natural Gas Building Regulations and the Benchmark Commissioning Checklist Main Combi 24 HE G.C.N 47 474 02 Building Regulations (England & Wales) require notification of the installation of a heating appliance to the relevant Local Authority Building Control Department. From 1 April 2005 this can be achieved via...
  • Page 3 INSTALLER NOTIFICATION GUIDELINES Choose Building Regulations Notification Route Competent Person's Building Control Self Certification Scheme Contact your relevant Local Install and Commission this Authority Building Control appliance to manufacturer's (LABC) who will arrange instructions an inspection or contact a government approved inspector Complete the Benchmark Checklist...

  • Page 4: Legislation

    LEGISLATION IMPORTANT - Installation, Commissioning, Service & Repair Main declare that no substances harmful to health are contained in the appliance or used during This appliance must be installed in accordance with the manufacturer’s appliance manufacture. instructions and the regulations in force. Read the instructions fully before installing or using the appliance.

  • Page 5: Introduction

    INTRODUCTION Description 1. The Main Combi 24 HE is a fully automatic gas fired wall mounted condensing combination boiler. It Case Front Panel is room sealed and fan assisted, and will provide central heating and mains fed domestic hot water.

  • Page 6: General Layout

    GENERAL LAYOUT Layout Air Pressure Switch Expansion Vessel Burner Manifold Automatic Air Vent DHW Plate Heat Exchanger Circulation Pump Drain Off Point Pressure Relief Valve Optional Integral Timer Position Central Heating System Pressure Gauge Control PCB Control Box 3-Way Valve Assembly Condensate Trap Flame Sensing Electrode Spark Electrode...

  • Page 7: Appliance Operation

    APPLIANCE OPERATION NOTE: All delay timers mentioned in 3.1 and 3.2 are overridden by domestic hot water demand. Central Heating Circuit Central Heating Mode (Fig. 4) 1. With a demand for heating, the pump circulates water through the primary circuit. At a pre- determined flow rate the central heating flow switch operates, initiating the ignition sequence.

  • Page 8: Technical Data

    TECHNICAL DATA Appliance Type Electrical Protection IPX4D Central Heating Primary Circuit Pressures Appliance Category CAT II 2H 3P NO x Class Safety Discharge Heat Input CH Condensate Drain 1” BSP Max Operating Min Operating Flue Terminal Diameter 100mm 24.8 10.6 Recommend Operating Dimensions Projection...

  • Page 9: Dimensions And Fixings

    DIMENSIONS AND FIXINGS Dimensions A 780mm B 345mm C 450mm D 116mm Ø Min. 360° Orientation E 185mm F 190mm G 131mm Tube Ø 100mm Fig. 6 Condensate Drain 68mm Gas Inlet Heating Domestic Hot Cold Water Heating Flow Water Outlet Inlet Return 95mm...

  • Page 10: System Details

    SYSTEM DETAILS Information 1. The Main Combi 24 HE Condensing Combination Boiler is a ‘Water Byelaws Scheme - Approved Product’. To comply with the Water Byelaws your attention is drawn to the following installation requirements and notes (IRN). a) IRN 001 - See text of entry for installation requirements and notes.
  • Page 11 SYSTEM DETAILS System Filling and Pressurising 1. A filling point connection on the central heating return pipework must be provided to facilitate initial filling and pressurising and also any subsequent water loss replacement/refilling. Double Stop Stop 2. There are connection points on the mains cold Check Valve Valve...
  • Page 12 SYSTEM DETAILS Domestic Hot Water Circuit Other Tap 1. All DHW circuits, connections, fittings, etc. should Outlets be fully in accordance with relevant standards and water supply regulations. Boiler Expansion Vessel 2. Your attention is drawn to: for GB: Guidance G17 to G24 and recommendation R17 to R24 of the Water Regulations Guide.

  • Page 13: Site Requirements

    SITE REQUIREMENTS Location 20mm/5mm Min 5mm Min 450mm see *NOTE: 1. The boiler may be fitted to any suitable wall with the flue passing through an outside wall or roof and discharging to atmosphere in a position permitting satisfactory removal of combustion products and providing an adequate air supply.
  • Page 14 SITE REQUIREMENTS Ventilation of Compartments 1. Where the appliance is installed in a cupboard or compartment, no air vents are required. 2. BS 5440: Part 2 refers to room sealed appliances installed in compartments. The appliance will run sufficiently cool without ventilation. Gas Supply 1.
  • Page 15 SITE REQUIREMENTS Condensate Drain Termination to an internal soil Boiler FAILURE TO INSTALL THE CONDENSATE DISCHARGE and vent pipe PIPEWORK CORRECTLY WILL AFFECT THE RELIABLE OPERATION OF THE BOILER The condensate discharge pipe MUST NOT RISE at any point along its length. There MUST be a fall of AT LEAST 2.5°...
  • Page 16 SITE REQUIREMENTS Flue NOTE: Due to the nature of the boiler a plume of water vapour will be discharged from the flue. This should be taken into account when siting the flue terminal. 1. The following guidelines indicate the general requirements for siting balanced flue terminals.
  • Page 17 SITE REQUIREMENTS Flue Dimensions The standard horizontal flue kit allows for flue lengths between 100mm and 685mm from elbow to terminal (Fig. 16). The maximum permissible flue length is: 4 metres. Flue Trim 1. The rubber flue trim supplied may be fitted to either the outside wall or on the inner wall of installation.
  • Page 18 SITE REQUIREMENTS 7.11 Flue Options 1. The Main Combi 24 HE can be fitted with flue systems as illustrated. 2. The standard flue is suitable only for horizontal applications. 3. Maximum permissible equivalent flue lengths are:- Horizontal Concentric 4 metres...

  • Page 19: Installation

    INSTALLATION Initial Preparation The gas supply, gas type and pressure must be checked for suitability before connection (see Section 7.4). 1. After considering the site requirements (see Section 7.0) position the fixing template on the wall ensuring it is level both horizontally and vertically.
  • Page 20 Wall Plate INSTALLATION Fitting The Boiler 1. Lift the boiler using the lower edges. Engage the slots at the top rear of the boiler on the wall plate hooks (Fig. 20). 2. Ensure that the boiler is level and sits against the wall.
  • Page 21 INSTALLATION Condensate Drain (see section 7.6) 1. Connect the condensate drain using the 1” BSP nut and seal supplied. Ensure the discharge of condensate complies with any national or local regulations in force (see British Gas “Guidance Notes for the Installation of Domestic Gas Condensing Boilers”.
  • Page 22 11. Fit the flue trim if required, and if necessary fit a terminal guard (see Section 7.9 & 7.10). VERTICAL FLUE 1. Only a flue approved with the Main Combi 24 HE can be used. Flue Elbow Flue Trim...
  • Page 23 INSTALLATION Making The Electrical Connections Fig. 30 To connect the mains input cable proceed as follows:- 1. Slacken the facia panel securing screws and lift the outercase panel so that its securing tabs are clear of the facia. Remove the panel. 2.

  • Page 24: Commissioning

    COMMISSIONING Commissioning the Boiler 1. Reference should be made to BS 5449 Section 5 when commissioning the boiler. 2. Open the mains water supply to the boiler. 3. Open all hot water taps to purge the DHW system. 4. Ensure that the filling loop is connected and open, then open the heating flow and return valves on the boiler.
  • Page 25 COMMISSIONING Checking the Burner Pressure 1. Turn on the gas and electrical supplies to the boiler and ensure that all external controls are calling for heat. 2. Set the hot water and central heating temperature controls to maximum and the selector switch to the Selector Switch OFF position (Fig.

  • Page 26: Completion

    10.0 COMPLETION 10.1 Completion Case Front Panel 1. Hinge the facia panel upwards and engage the securing screws. Refit the case front panel and tighten the screws (Fig. 40). 2. Instruct the user in the operation of the boiler and system, explaining the operational sequence.

  • Page 27: Servicing The Boiler

    11.0 SERVICING THE BOILER Case Front Panel 11 .1 Annual Servicing 1. For reasons of safety and economy, it is recommended that the boiler is serviced annually. Servicing must be performed by a competent person. 2. After servicing, complete the relevant Service Interval Record section of the Benchmark Commissioning Checklist at the rear of this publication.
  • Page 28 11.0 SERVICING THE BOILER Baffle Spring Clip 11.1 Annual Servicing (Cont) 10. Ease the front edge of the left hand baffle upwards, disengaging the spring clip. Disengage the tab on the baffle from the slot in the fan hood (Fig.44). 11.

  • Page 29: Changing Components

    12.0 CHANGING COMPONENTS IMPORTANT: When changing components ensure Pressure that both the gas and electrical supplies to the Switch boiler are isolated before any work is started. See Section 11.1 “Annual Servicing” for removal of Fig. 49 Sensing case panel, door etc. Tubes 12.1 Fan (Figs.
  • Page 30 12.0 CHANGING COMPONENTS 12.3 Heat Exchanger (Fig. 52) 1. Remove the fan as described in section 12.1. 2. Drain the primary circuit. Prise the pipe connecting clips off the joints in the flow and return pipes. Remove the heat exchanger return pipe. 3.
  • Page 31 12.0 CHANGING COMPONENTS 12.5 Injectors (Fig. 54) Injector Inlet Elbow 1. Remove the burner as described in Section 12.4. Manifold Injector 2. Undo the screws securing the injector manifold to the inlet elbow and remove the manifold. Fig. 54 3. Unscrew and replace injectors as required and Gasket examine the sealing gasket, replacing as necessary.
  • Page 32 12.0 CHANGING COMPONENTS 12.8 Gas Valve (Fig. 56) Modulator Wires 1. Undo the nut on the gas feed pipe at the tap rail under the boiler. Ignition Lead 2. Completely undo the securing screws and hinge Gas Valve the facia panel down. 3.
  • Page 33 12.0 CHANGING COMPONENTS 12.11 Pump - Head Only (Figs. 58 & 59) 1. Drain the primary circuit and remove the socket head screws securing the pump head to the body and draw the head away. 2. Undo the screw on the pump wiring cover and remove the cover.
  • Page 34 12.0 CHANGING COMPONENTS 12.14 Pressure Gauge (Figs. 61 & 62) 1. Drain the primary circuit and undo the nut on the pressure gauge capillary. 2. Remove the timer cover and ease the timer wiring aside. Undo the screws securing the gauge retaining bracket.
  • Page 35 12.0 CHANGING COMPONENTS 12.17 Pressure Relief Valve (Fig. 65) 1. Drain the primary circuit. 2. Disconnect the discharge pipe from the valve. Using a suitable hexagon key undo the grub screw sufficiently to release the valve. 3. Note the orientation of the valve, rotate it and withdraw it from the manifold.
  • Page 36 12.0 CHANGING COMPONENTS Plate Heat Exchanger 12.20 Plate Heat Exchanger (Fig. 68) Fig. 68 1. Drain the primary circuit. 2. While supporting the heat exchanger undo the screws securing it to the brass manifolds. 3. Withdraw the heat exchanger upwards and to the left of the gas valve, taking care not to damage any wires or controls.
  • Page 37 12.0 CHANGING COMPONENTS 12.21 Diverter Valve Assembly (Cont) Central Heating Microswitch & Pressure Differential Bracket CH Pressure Differential Valve (Fig. 71) Valve 1. Remove the DHW pressure differential valve as Sensing Pipe described above. 2. From the brass diverter manifold undo the nut on By-pass the heating flow pipe.
  • Page 38 12.0 CHANGING COMPONENTS Secondary 12.23 Secondary Heat Exchanger (Fig. 73) Heat Exchanger 1. Drain the primary circuit Pipe Connecting Clip 2. Undo the four screws securing the right hand case panel. Remove the panel. Fan Spigot Outlet 3. Prise the connecting clips from the heat Pipe Clamp exchanger return pipe and the boiler return pipe.

  • Page 39: Electrical

    13.0 ELECTRICAL 13.1 Illustrated Wiring Diagram Pump Mains Input Link On/Off/Reset Selector Switch Fuse Temperature Sensor Hydraulic Differential Pressure Switch Flue Thermostat Optional Timers Gas Valve Control PCB Safety Thermostat Air Pressure 3-Way Valve Microswitch Switch Flame Sensing Electrode Condensate Trap - brown - black...

  • Page 40: Short Parts List

    14.0 SHORT PARTS LIST Short Parts List Key G.C. Description Manufacturers Part No. 5112627 Pressure Switch 5112999 Heat Exchanger 5112431 Burner 5112770 E66 402 Injector - 1.18 NG 248210 E66 408 Electrode Lead 248037 E66 411 Spark or Sensing Electrode 247384 Pump Complete 248042 E66 432 Hydraulic Outlet Assembly...

  • Page 41: Fault Finding

    15.0 FAULT FINDING Carry out initial fault finding checks 1. Check that gas, water and electrical supplies are available at the boiler. Electrical supply = 230V ~ 50 Hz. CH water system pressurised to 0.5 bar when the boiler is cold. The preferred minimum gas pressure is 19.5mbar (natural gas), or 36mbar (propane).
  • Page 42 15.0 FAULT FINDING Domestic Hot Water - Follow operational sequence Turn selector to Replace diaphragm Go to section ‘A’ neon illuminated Is mains water DHW flow valve filter and differential diaphragm damaged assembly clean? Turn thermostat to DHW flow rate more than DHW flow valve rod max.
  • Page 43 15.0 FAULT FINDING Fault Finding Solutions Sections A to E Is there 230V at: Main terminals L and N Check electrical supply Main terminal fuse Replace fuse neon Replace PCB illuminated Selector terminals a & b Check wiring and a & 3. PCB - M1 Replace selector connector terminals 9 &...
  • Page 44 15.0 FAULT FINDING Check and correct if necessary 1. Electrical and pressure tube connections Replace air 2. Blockage of pressure tubes pressure switch 3. Restriction in flue 4. Venturi Gas at burner Ensure gas is on and purged PCB - M4 connector is approx 230V AC, Replace gas valve terminals 36 &...
  • Page 45 15.0 FAULT FINDING Ensure that mains input terminal L is Live (230V) and N is Neutral (0V) Check and correct if necessary 1. Flame sensing electrode and lead connections 2. Electrode position Replace PCB Flame current should be 1 µA approx. Replace flame sensing electrode Boiler overheat thermostat Allow to cool.

  • Page 46: Benchmark Checklist

    5 1 1 5 8 0 9 BENCHMARK No. GAS BOILER COMMISSIONING CHECKLIST C O L L E C T I V E M A R K BOILER SERIAL No. NOTIFICATION No. CONTROLS To comply with the Building Regulations, each section must have a tick in one or other of the boxes TIME &...
  • Page 47 SERVICE INTERVAL RECORD It is recommended that your heating system is serviced regularly and that you complete the appropriate Service Interval Record Below. Service Provider. Before completing the appropriate Service Interval Record below, please ensure you have carried out the service as described in the boiler manufacturer’s instructions.
  • Page 48 - Iss. 4 Publication No. 5115809 (04/2006) General Enquiries (GB) 08706 060 780 Tel. Technical (GB) 08706 049 049 Tel. Service (GB) 08701 655 644 Tel. 01926 410 006 Fax. Literature Request (GB) 08706 060 623 Tel. Technical (IE) 1850 560570 Tel.

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