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6.0 System Details

© Baxi Heating UK Ltd 2011

6.1

Information

1. The Main Combi Eco 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.

b) IRN 302 -

Byelaw 14.

2. Reference to the WRc publications, ‘Water fittings and
materials directory’ and ‘Water supply byelaws guide’ give full
details of byelaws and the IRNs.

6.2

Central Heating Circuit

1. The appliance is suitable for fully pumped SEALED
SYSTEMS ONLY. 

Treatment of Water Circulating Systems
• All recirculatory water systems will be subject to corrosion
unless an appropriate water treatment is applied. This means
that the efficiency of the system will deteriorate as corrosion
sludge accumulates within the system, risking damage to
pump and valves, boiler noise and circulation problems.

• When fitting new systems flux will be evident within the
system, which can lead to damage of system components.

• All systems must be thoroughly drained and flushed out
using, for example, Sentinel X300 or X400 or Fernox F3.
They should be used following the flushing agent
manufacturer’s instructions.

• System additives - corrosion inhibitors and flushing 
agents/descalers should comply to BS7593 requirements, e.g.
Sentinel X100 and Fernox MB-1 which should be used
following the inhibitor manufacturer’s instructions. 

• Full instructions are supplied with the products, for further
information contact Sentinel (0800 389 4670) or Fernox
(0870 870 0362)

Failure to flush and add inhibitor to the system will
invalidate the appliance warranty.

• It is important to check the inhibitor concentration after
installation, system modification and at every service in
accordance with the manufacturer’s instructions. (Test kits are
available from inhibitor stockists.)

• For information or advice regarding any of the above
contact Technical Enquiries.

6.3

Bypass

1. The boiler utilises the primary side of the DHW plate heat
exchanger as an automatic integral bypass.

6.4

System Control

1. Further external controls (e.g. room thermostat) should be
fitted to optimise the economical operation of the boiler.

Summary of Contents for Main Combi 25 Eco

Page 1: ... Baxi Heating UK Ltd 2011 Installation Service Instructions Combi Eco Range These instructions include the Benchmark Commissioning Checklist and should be left with the user for safe keeping ...

Page 2: ...ly applies if the appliance is being installed in a dwelling or some related structure The flowchart opposite gives guidance for installers on the process necessary to ensure compliance with Building Regulations Baxi Heating UK Ltd 2011 All rights reserved No part of this publication may be reproduced or transmitted in any form or by any means or stored in any retrieval system of any nature includ...

Page 3: ...elevant LABC You must ensure that the certificate number issued by the Gas Safe Register is written onto the Benchmark Checklist Scheme Members only Call Gas Safe Register on 0800 408 5577 or log onto www GasSafeRegister co uk within 10 days If you notify via the Gas Safe Register the register will issue the Building Regulations certificate on members behalf Complete the Benchmark Checklist Instal...

Page 4: ...iven reference should be made to the relevant British Standard Code of Practice In IE the installation must be carried out by a competent Person and installed in accordance with the current edition of I S 813 Domestic Gas Installations the current Building Regulations and reference should be made to the current ETCI rules for electrical installation All systems must be thoroughly flushed and treat...

Page 5: ...s clear and unobstructed If possible avoid steps wet or slippery surfaces unlit areas etc and take special care on ladders into lofts Technique When handling or lifting always use safe techniques keep your back straight bend your knees Don t twist move your feet avoid bending forwards and sideways and keep the load as close to your body as possible Where possible transport the boiler using a sack ...

Page 6: ... Fixings 11 6 0 System Details 12 7 0 Site Requirements 15 8 0 Flue Options 19 9 0 Plume Displacement 24 10 0 Installation 28 11 0 Commissioning 33 12 0 Completion 35 13 0 Servicing 36 14 0 Changing Components 38 15 0 Setting the Gas Valve 47 16 0 Electrical 48 17 0 Short Parts List 49 18 0 Fault Finding 50 Benchmark Checklist 58 Section Page ...

Page 7: ... is situated on the front sloping face of the hydraulic plate It is visible when the case front panel is removed and the control box hinged down Fig 1 1a 6 The boiler model name and serial number are also shown on the information label on the back of the facia door This is for user reference 7 The boiler is intended to be installed in residential commercial light industrial E M C environments on a...

Page 8: ...rap 13 Heat Exchanger Air Vent 14 Electrode Assembly 15 Primary Heat Exchanger 16 Fan Assembly 17 On Off Reset Selector Switch 18 Central Heating Temperature Control 19 Hot Water Temperature Control 20 Water Pressure Sensor 21 Gas Air Inlet 22 Burner Mounting Panel 23 Igniter 24 Burner On Light 25 Central Heating Mode Light 26 Domestic Hot Water Mode Light 27 Display 28 Position of Optional Integr...

Page 9: ...ler will not operate and the integral timer will require resetting once the selector switch is set to either Position or Position 3 3 Frost Protection Mode 1 The frost protection mode is integral to the appliance and functions only with the selector switch see Section 2 1 in the domestic hot water and central heating position If the system temperature falls below 5 C then the boiler will fire on i...

Page 10: ...3 3 5 4 Metre wg Flow Rate l h Pump Available Head 0 5 5 5 4 5 Clearances Above Casing 200 mm Min 300mm Min 80 125 Below Casing 200 mm Min Front 450 mm Min For Servicing Front 5 mm Min In Operation L H Side 5 mm Min R H Side 5 mm Min In Operation Heat Input CH Net Max Min 25 model kW 26 06 7 82 30 model kW 29 32 8 8 Heat Output CH Non Condensing Max Min 25 model kW 25 94 7 61 30 model kW 28 63 8 5...

Page 11: ... Ø Min F 145mm G 132mm 210mm 80 125 H 225mm Domestic Hot Water Outlet 15mm Cold Water Inlet 15mm Heating Return 22mm Heating Flow 22mm Pressure Relief Valve 15mm Gas Inlet 22mm 65 mm 65 mm 65 mm 65 mm 65 mm 127 mm Condensate Drain Tap Rail 360 Orientation Tube Ø 100mm D C B A G F At Least 1 5o H H ...

Page 12: ...hich can lead to damage of system components All systems must be thoroughly drained and flushed out using for example Sentinel X300 or X400 or Fernox F3 They should be used following the flushing agent manufacturer s instructions System additives corrosion inhibitors and flushing agents descalers should comply to BS7593 requirements e g Sentinel X100 and Fernox MB 1 which should be used following ...

Page 13: ... to 0 5 bar Therefore the minimum cold fill pressure is 0 5 bar The vessel is suitable for correct operation for system capacities up to 125 litres 24 155 litres 27 30 For greater system capacities an additional expansion vessel must be fitted For GB refer to BS 7074 Pt 1 For IE the current edition of I S 813 Domestic Gas Installations 6 7 Pressure Relief Valve Fig 6 1 The pressure relief valve is...

Page 14: ...op cock water meter or water treatment device already fitted to the wholesome water supply connected to the boiler domestic hot water DHW inlet supply then a suitable expansion device may be required 5 If the hot water expansion is not provided for then high pressures can develop which may result in damage to fittings and devices on the system 6 The boiler s maximum working mains pressure is 8 bar...

Page 15: ...vant requirements In GB this is the current I E E Wiring Regulations and Building Regulations In IE reference should be made to the current edition of I S 813 Domestic Gas Installations and the current ETCI rules 4 If the boiler is to be fitted into a building of timber frame construction then reference must be made to the current edition of Institute of Gas Engineers Publication IGE UP 7 Gas Inst...

Page 16: ...ns In IE reference should be made to the current edition of ETCI rules 2 The mains supply is 230V 50Hz fused at 3A NOTE The method of connection to the electricity supply must facilitate complete electrical isolation of the appliance Connection may be via a fused double pole isolator with a contact separation of at least 3mm in all poles and servicing the boiler and system controls only 7 6 Bath S...

Page 17: ... discharge pipe should be treated as an external run 9 In all cases discharge pipe must be installed to aid disposal of the condensate To reduce the risk of condensate being trapped as few bends and fittings as possible should be used 10 When discharging condensate into a soil stack or waste pipe the effects of existing plumbing must be considered If soil pipes or waste pipes are subjected to inte...

Page 18: ... in accordance with the diagram below Opening Window or Door 150mm MIN IMPORTANT If fitting a Plume Displacement Flue Kit the air inlet must be a minimum of 150mm from any opening windows or doors see Section 9 0 Fig 18a Plume Displacement Kit Air Inlet Terminal Position with Minimum Distance Fig 18 mm A1 Directly below an opening air brick opening windows etc 300 B1 Above an opening air brick ope...

Page 19: ...elbow supplied with the standard horizontal telescopic flue kit is not included in any equivalent length calculations NOTE Flue length is measured from point i to ii as shown IMPORTANT All flue systems must be securely supported at least once every metre Suitable pipe supports are available as accessories Horizontal Flues ii i Plume Displacement Kit 60 100 Ø 1M Extensions 45 93 elbows are also ava...

Page 20: ...o of fittings pipes Sub total Equivalent Length Value Equivalent Length Air Duct 6 5m 1m extension 135 bend 91 5 bend 1m 0 25m 0 5m 5 2 2 5 0m 0 5m 1 0m FLUE DUCT No of fittings pipes Sub total Equivalent Length Value Equivalent Length Flue Duct 6 5m ii i C Roof Terminal A B This bend is equivalent to 1 metre Total Equivalent Length A B C 1x90 Bend All vertical and angled runs must be included mea...

Page 21: ...lue System 80mm diameter E Flue Extension pair 1000mm 5111087 F Flue Bend pair 90 5111072 G Flue Bend 2 pair 135 5111086 J Vertical Flue Boiler Adaptor Kit 720089801 H Vertical Flue Adaptor 5111084 W Pipe Support pair 80mm 5111081 Y Flue Termination Kit horizontal termination 80mm 5120172 Z Single Terminal 80mm 5121791 Q Adaptor 60 80 5121792 T Pitched Roof Terminal 25 45 5106164 FLUE GROUP G Flue...

Page 22: ... adaptor in the boiler adaptor making sure that it is pushed down as far as possible 2 Ensure that the air flue ducts are connected correctly and that they are adequately supported at least once every metre using the available pipe supports 3 Ensure that all joints and elbows are fully engaged and cannot become disconnected during operation Flue Duct Connection Boiler Adaptor Air Duct Connection ...

Page 23: ...p supplied IMPORTANT If the boiler is not fitted immediately after the flue system temporary precautions must be taken to prevent rain entry into the room of installation Any precautionary measures must be removed prior to commissioning the boiler 8 7 Flue Dimensions The standard horizontal flue kit allows for lengths between 100mm and 685mm from elbow to terminal Fig 19 The maximum permissible eq...

Page 24: ...rease with the addition of extensions the length of either or both the 60 100 concentric and 60Ø exhaust 5 Standard concentric flue extension kits may be added between the boiler elbow and the terminal assembly 6 The minimum length of the concentric flue is 100mm when measured from the edge of the flue elbow IMPORTANT The maximum equivalent length of concentric flue is 8 metres Additional bends ma...

Page 25: ...st and any extensions or additional bends Example 1 Not Permissible If for instance a concentric length of 5 metres was required and the 60Ø exhaust needed to be 10 metres the graph shows that this combination would NOT be permissible as the intersection point would be above the solid diagonal line Example 2 Flue Lengths OK Where both lengths have been determined they can be applied to the graph t...

Page 26: ... that the concentric assembly and any extensions fall back to the boiler at an angle of at least 1 5 and that the external air inlet is to the bottom 8 Use suitable brackets to support the concentric assembly and any extensions and make good inside and outside 9 The 60Ø exhaust can now be fitted Slide the adaptor over the plain end of the 60Ø exhaust Fig 31 and engage the exhaust in the terminal S...

Page 27: ...the extension at 30mm as shown in two positions directly opposite each other Fig 36 20 Using a suitable bit e g 2mm drill through the extension and outlet Secure using two of the screws supplied 21 The remaining screw must be used to secure the adaptor to the concentric terminal 22 When the plume outlet is positioned under a balcony or other projection Fig 37 it must protrude at least 200mm it is ...

Page 28: ... Mark the position of the centre of the flue hole rear exit For side flue exit mark as shown Fig 40 5 If required mark the position of the gas and water pipes Remove the template 6 Cut the hole for the flue minimum diameter 116mm 7 Drill the wall as previously marked to accept the wall plugs supplied Secure the wall plate using the fixing screws 8 Using a spirit level ensure that the plate is leve...

Page 29: ...ischarge pipe supplied 3 The pipework must be at least 15mm diameter and run continuously downwards to a discharge point outside the building See section 6 7 for further details 4 Utilising one of the sealing washers connect the discharge pipe to the adaptor and tighten the nut 5 Complete the discharge pipework and route it to the outside discharge point IMPORTANT Make all soldered joints before c...

Page 30: ...icator line Fig 46 NOTE The flue elbow is angled at 93 degrees to ensure a fall back to the boiler 3 Measure the distance from the outside wall face to the elbow This dimension will be known as X Fig 48 4 To dimension X add 50mm This dimension to be known as Y IMPORTANT Check all dimensions before cutting 5 Mark dimension Y on the flue as shown Fig 49 Carefully cut the waste material from the flue...

Page 31: ...ect boiler operation and prevent water entering the flue 11 Make good between the wall and air duct outside the building 12 Fit the flue trim if required and if necessary fit a terminal guard see Section 8 8 8 9 CONCENTRIC VERTICAL FLUE 15 Once the length of the vertical concentric extension has been determined mark and carefully cut off the excess material The cut end MUST be square and free of b...

Page 32: ...e thermostat The switched output from the thermostat must be connected to terminal 2 Fig 57 If the room thermostat being used incorporates an anticipator it MUST be wired as shown in Fig 57 7 Ensure that the external control input cable s have sufficient slack to allow the control box to drop down Tighten the cable clamp on the boiler chassis 8 Replace the terminal block cover routing the external...

Page 33: ...60 then close and disconnect the filling loop 9 Turn the gas supply on and purge according to in GB BS 6891 and in IE I S 813 Domestic Gas Installations 10 Test for gas soundness 11 Hinge the facia panel upwards and refit the case front panel Tighten the securing screws IMPORTANT The combustion for this appliance has been checked adjusted and preset at the factory for operation on the gas type spe...

Page 34: ... be obtained with all other gas appliances in the property working Measure the Gas Rate 8 With any other appliances pilot lights turned OFF the gas rate can be measured It should be between 25 model 2 76 m3 h 30 model 3 17 m3 h 9 The Calibration Function is active for 20 minutes unless the maximum CH temperature is exceeded 10 The function can be disabled at any time by turning the DHW temperature...

Page 35: ...re relevant to the appliance and installation These details will be required in the event of any warranty work The publication must be handed to the user for safe keeping and each subsequent regular service visit recorded 4 For IE it is necessary to complete a Declaration of Conformity to indicate compliance with I S 813 An example of this is given in I S 813 Domestic Gas Installations This is in ...

Page 36: ...ing the requirements of BS7927 or BS EN50379 3 and be calibrated in accordance with the analyser manufacturers requirements Competence can be demonstrated by satisfactory completion of the CPA1 ACS assessment which covers the use of electronic portable combustion gas analysers in accordance with BS 7967 Parts 1 to 4 Check the Combustion Performance CO CO2 ratio 4 Set the boiler to operate at maxim...

Page 37: ...ow of domestic hot water is diminished it may be necessary to clean the filter 14 Initially check the cold water inlet tap filter 15 Turn the tap off and draw off from a hot tap Undo the blanking cap and remove the threaded bush Fig 75 16 Extract the filter and rinse thoroughly in clean water Reassemble and check the flow If required clean the restricter filter as described below 17 Pull off the H...

Page 38: ...1 Disconnect the igniter feed plug and the electrode leads noting their positions 2 Undo the nuts and screws securing the igniter to the boiler top panel Remove the igniter 3 Fit the new igniter and reassemble in reverse order 14 2 Electrode Assembly Fig 78 1 Disconnect the electrode lead caps remove the strain relief clip from the sensing lead and disconnect the lead 2 Undo the extended nuts secu...

Page 39: ...n Examine and replace the gasket if necessary 6 Remove the four nuts and separate the fan from the gas air inlet Note the position of the orifice plate and examine the gasket replacing if necessary Fig 81 7 Fit the new fan ensuring that the orifice plate is correctly fitted and that the gasket is in position 8 Examine the insulation around the burner and the heat exchanger gasket and replace if ne...

Page 40: ...t the new burner and gasket examine the insulation and heat exchanger gasket replacing if necessary 7 Reassemble in reverse order 14 6 Insulation Fig 82 1 Undo the nut on the gas pipe at the gas air inlet and the gas valve Remove the pipe taking care not to lose the sealing washers Also remove the injector 2 Disconnect the electrode lead caps remove the strain relief clip from the sensing lead and...

Page 41: ...nsor Fig 85 1 Drain the boiler primary circuit 2 Disconnect the plug from the sensor 3 Unscrew the sensor from the hydraulic outlet assembly examine the sealing washer and replace if necessary 4 Reassemble in reverse order ensuring that the plug is pushed fully onto the new sensor 14 10 DHW Temperature Sensor NTC Fig 85 1 Turn off the mains cold water supply tap and draw off the residual domestic ...

Page 42: ...w head The pump speed must be set to 3 Fig 88 4 Reassemble in reverse order 14 13 Pump Complete Fig 89 1 Drain the boiler primary circuit 2 Undo the two screws securing the body to the pipe and manifold and draw the pump forwards 3 Undo the screw on the pump wiring cover and remove the cover Using a suitable flat bladed screw driver press the cable securing levers downwards to release each wire af...

Page 43: ...he electrical plug from the sensor 3 Connect the plug to the new sensor Carefully fit the new sensor to the hydraulic assembly ensuring it is fully down 14 17 Pressure Relief Valve Fig 93 1 Drain the boiler 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 a...

Page 44: ...hand location stud is offset towards the centre more than the right hand one 7 Reassemble in reverse order 14 19 Diverter Valve Motor Unit Assembly Figs 95 96 1 To replace the motor unit disconnect the multi pin plug 2 Pull off the retaining clip and remove the motor unit 3 The motor unit can now be replaced or the valve assembly removed 4 Drain the primary circuit and draw off any hot water once ...

Page 45: ...e 5 Reassemble in reverse order ensuring that the temperature controllers are reset to their previous positions 14 21 Selector Switch Figs 97 98 1 Note the setting of the selector switch knob and carefully pull it off the facia 2 Completely undo the screws securing the control box cover and release the cover retaining barbs from their slots Disengage the rear of the cover from the control box hing...

Page 46: ...rior to final setting use a suitable hexagon key to wind out the Throttle Adjustment Screw until it is flush with the valve body then turn the screw 4 full turns clockwise Fig 99a If the boiler will not light or the correct CO2 cannot be achieved contact the heateam technical helpline 14 23 Expansion Vessel Fig 100 1 Drain the boiler primary circuit and undo the nut on the vessel connection pipe 2...

Page 47: ...the correct reading is obtained Fig 108 Turning clockwise will reduce the CO2 Anticlockwise will increase the CO2 9 The CO2 must then be checked at minimum rate Turn the CH temperature knob fully anticlockwise As the knob is turned the display will change indicating the fan speed When the display reads 0 the boiler runs at minimum rate The CO2 should be 8 4 0 0 0 4 10 With the boiler on minimum th...

Page 48: ...erheat Stat Pump X400 X401 g g b b r r b b b br bk g b br g y b br b br br b b b br br br b b br r bk r bk Water Pressure Switch Spark Generator Ignition Electrode 9 8 7 6 5 4 3 2 1 9 10 8 7 6 5 4 3 2 1 Hall Effect Sensor r w b w r bk bk r w DiverterValve Optional IntegralTimer 1 2 3 4 1 2 3 4 bk br bk b N L br br 1 4 2 5 3 1 2 a b Link b g y br Mains Input br b bk bk bk grey gr gr gr bk E N L 16 ...

Page 49: ... Assembly 5130293 422 Gas Valve 720301001 404 Hall Effect Sensor 5114767 313 Burner 5130292 419 Water Pressure Switch 5114748 400 Plate Heat Exchanger 248048 415 Pump 248042 421 NTC Sensor DHW 5114725 420 Overheat Thermostat 5114729 304 NTC Sensor CH 5130291 504 Pressure Gauge 248090 503 PCB 25 5120217 PCB 30 5120218 313 426 326 422 404 419 400 415 503 504 320 304 421 420 ...

Page 50: ...preceded by the letter E For example code E133 will be displayed by E1 alternating with 33 E50 is shown as E then 50 E20 E28 E50 indicate faulty or incorrect components E110 shows overheat of the primary water E119 is displayed when the primary water pressure is less than 0 5 bar E133 indicates that the gas supply has been interrupted ignition has failed or the flame has not been detected E125 is ...

Page 51: ...ng Go to section D Error 133 flashing Burner does not stay alights after 5 seconds Error 133 flashing Go to section I Operation sequence successful If the error 110 is still flashing Go to section J Fan runs at correct speed YES YES NO NO NO YES YES YES YES YES YES YES YES NO YES YES YES YES NO NO NO NO NO Burner output modulates to maintain the temperature set Burner goes out Go to section C Ensu...

Page 52: ...hts after 5 seconds Error 133 flashing Go to section I Operation sequence successful Turn the selector switch to reset position for 5 seconds If the error 110 is still flashing Go to section J Fan runs at correct speed YES YES NO NO NO YES YES YES YES YES YES YES YES NO YES YES YES YES NO NO NO NO NO Burner output modulates to maintain the temperature set DHW flow sensor senses no flow Burner goes...

Page 53: ...onnector terminals 3 4 Replace PCB 2 NO Change pump supply cable YES B CH system pressure less than 0 5 bar Re pressurise system 1 YES Check the tap of the automatic air vent is opened Open the automatic air vent 2 NO C 1 NO YES Fan connections correct at fan PCB X2 connector is 230V AC across terminals 5 7 Fan jammed or faulty winding Replace PCB Replace fan YES D If pump jammed release NO NO Rep...

Page 54: ... Check and correct if necessary 1 Ignition electrode and lead 2 Electrode connection 3 Spark gap and position voltage at PCB X2 connector is 110V AC across terminals 2 5 Note from multimeter connect common to 2 volys to 5 Check wiring YES NO Replace igniter YES H YES 1 Ensure that the Hall Effect Sensor is in position Check the connection between the PCB X400 connector terminals 3 6 7 and the elec...

Page 55: ...inals Allow to cool Continuity across thermostat terminals more than 1 5 ohm J L M Is there 230V at Motor 3 way valve Replace motor 3 way valve 1 YES PCB X3 connector terminals 5 6 central heating mode 5 7 domestic hot water mode Replace PCB 2 NO Change pump supply cable YES Fan connections correct at fan PCB X401 connector terminals 5 6 7 8 1 YES Replace fan Temperature sensors faulty Cold resist...

Page 56: ...56 19 0 Notes Baxi Heating UK Ltd 2011 ...

Page 57: ...57 19 0 Notes Baxi Heating UK Ltd 2011 ...

Page 58: ...ect the customer s statutory rights If yes and if required by the manufacturer has a water scale reducer been fitted CONDENSING BOILERS ONLY The condensate drain has been installed in accordance with the manufacturer s instructions and or BS5546 BS6798 Yes If the condensate pipe terminates externally has the pipe diameter been increased and weatherproof insulation fitted Yes 58 ...

Page 59: ...r Name Company Name Telephone No Gas Safe Register No Comments Signature Date Engineer Name Company Name Telephone No Gas Safe Register No Comments Signature Date Engineer Name Company Name Telephone No Gas Safe Register No Comments Signature Date Engineer Name Company Name Telephone No Operative ID No Comments Signature Date Engineer Name Company Name Telephone No Gas Safe Register No Comments Si...

Page 60: ...cal Enquiries 0844 871 1555 Website www mainheating co uk e oe All descriptions and illustrations provided in this leaflet have been carefully prepared but we reserve the right to make changes and improvements in our products which may affect the accuracy of the information contained in this leaflet All goods are sold subject to our standard Conditions of Sale which are available on request ...

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