background image

Baxi Maxflow Combi FS

Gas Fired Floor Standing Combination Boiler

with Unvented Hot Water Storage

Installation and 
Servicing Instructions

Please leave these instructions with the user

IMPORTANT: This boiler MUST be installed with 

the Unvented Kit Part No. 247369 which is in 

a separate box supplied with the boiler

Summary of Contents for Maxflow Combi FS

Page 1: ...ion Boiler with Unvented Hot Water Storage Installation and Servicing Instructions Please leave these instructions with the user IMPORTANT This boiler MUST be installed with the Unvented Kit Part No 247369 which is in a separate box supplied with the boiler ...

Page 2: ...to buy Everyone who works at Baxi has a commitment to quality because we know that satisfied customers mean continued success We hope you get a satisfactory service from Baxi If not please let us know Baxi Maxflow Combi FS G C No 47 075 10 Baxi is a BS EN ISO 9001 Accredited Company The boiler meets the requirements of Statutory Instrument The Boiler Efficiency Regulations 1993 No 3083 and is deem...

Page 3: ...7 5 0 Dimensions and Fixings 8 6 0 System Details 9 7 0 Site Requirements 13 8 0 Installation 18 9 0 Commissioning the Boiler 24 10 0 Servicing the Boiler 26 11 0 Changing Components 28 12 0 Illustrated Wiring Diagram 40 13 0 Fault Finding 41 14 0 Short Parts List 45 Section Page Contents ...

Page 4: ...is positioned on the boiler base panel Fig 2 9 The boiler is intended to be installed in residential commercial light industrial E M C environments on a governed meter supply only 10 The boiler must be installed with one of the purpose designed flues such as the standard horizontal flue kit 11 All systems must be thoroughly flushed and treated with inhibitor see section 6 2 1 2 Installation 1 The ...

Page 5: ...ermostat 24 Flow Temperature Sensor 25 Electrical Control Box 26 Temperature Gauge Sensor 27 Filling Loop Connections 28 Diverter Valve 29 Storage Cylinder Temperature Sensor 30 Indicator Neons 31 Domestic Hot Water Temperature Control 32 ON OFF Selector Switch 33 Central Heating Temperature Control 34 Flame Failure Reset Button 35 Reset Button 2 2 Optional Extras 1 Various flue extensions bends v...

Page 6: ...ic hot water within the store to the temperature set by the adjustable domestic hot water control knob When this temperature is reached the burner extinguishes and the fan stops The pump continues to run for 3 minutes to prevent residual heat build up in the boiler When the hot water demand has been satisfied the 3 way diverter valve operates to divert the primary heating water to the central heat...

Page 7: ... DHW kW 31 1 11 9 Btu h 106 130 40610 Heat Output Max Min C H DHW kW 28 0 10 4 Btu h 95 555 35 492 Electrical Supply 230V 50Hz Power Consumption 190W External Fuse Rating 3A Internal Fuse Rating F2A External Controls 230V switching Electrical Protection IPx4D Appliance must be connected to an earthed supply Appliance Category CAT II 2H 3 Gas Rate Natural Gas Max Min After 10 Mins m3 h 3 29 1 26 ft...

Page 8: ...G C C F E B D Outer Case Rear of Case View From Above Centre line of pressure relief valve is 803mm above floor level All others are 823mm above floor level 50mm Gas Inlet 22mm Cold Mains Inlet 15mm Hot Water Outlet 15mm Heating Return 22mm Pressure Relief Valve 22mm Heating Flow 22mm 80mm 60mm 50mm 40mm 40mm ...

Page 9: ...ms For optimum performance after installation this boiler and its associated central heating system must be flushed in accordance with the guidelines given in BS 7593 Treatment of water in domestic hot water central heating systems This must involve the use of a proprietary cleanser such as BetzDearborn Sentinel X300 or X400 or Fernox Superfloc Full instructions are supplied with the products but ...

Page 10: ...n external by pass For example a 15mm pipe between the flow and return controlled by a valve or an uncontrolled radiator 6 4 System Control 1 The boiler is designed for use in a heating system that incorporates external controls i e a minimum of a timer device 2 Suitable timer kits are available as optional extras 3 For optimum operating conditions and maximum economy the fitting of a programmable...

Page 11: ...ved at both ends after use 6 6 Expansion Vessel Fig 7 Central Heating only 1 The appliance expansion vessel is pre charged to 0 8 bar Therefore the cold fill pressure is 0 8 bar The vessel is suitable for correct operation for system capacities up to 125 litres 27 5gal For greater system capacities an additional expansion vessel must be fitted refer to BS 7074 Pt 1 6 7 Pressure Relief Valve Fig 8 ...

Page 12: ...ducing valve supplied in the Unvented Kit must be fitted The manufacturer of any outlet fittings such as a shower valve may require a lower maximum pressure The pressure reduction must take account of all fittings connected to the DHW system 6 9 Showers 1 If a shower control is supplied from the appliance it should be of the thermostatic or pressure balanced type Thermostatic type shower valves pr...

Page 13: ...ating valves 2 Sufficient clearance must be left at one side to accommodate the components of the unvented kit The clearance should be at least 300mm to fit the D H W expansion vessel tundish and attendant pipework IMPORTANT When installing a left hand flue system it is not practical to site the components of the unvented kit to the left of the boiler 3 The floor must be flat and level extending f...

Page 14: ...on of Compartments 1 The boiler does not require any air vents in the room in which it is installed If it is installed in a cupboard or compartment permanent air vents are required at high and low levels see Table 1 The vents must communicate with the same room or be direct to outside on the same wall 2 When installed in a cupboard or compartment the minimum clearances must be maintained 7 6 Gas S...

Page 15: ...Minimum Distance Fig 10 mm A Directly below an openable window air vent or any other ventilation opening 300 B Below gutters drain or soil pipes 25 C Below eaves 25 D Below balconies or car port roof 25 E From vertical drain pipes and soil pipes 25 F From internal or external corners 25 G Above ground or balcony level 300 H From a surface facing a terminal 600 I Facing a terminal 1200 J For an ope...

Page 16: ...quired 2 Remove the protective backing from the adhesive seal Apply the seal to the rear of the trim flange Fig 18 3 Locate the trim over the flue terminal and push it back to the wall to compress the seal Fig 19 7 11 Terminal Guard Fig 20 1 When codes of practice dictate the use of terminal guards they can be obtained from most Plumbers and Builders Merchants 2 There must be a clearance of at lea...

Page 17: ...ions of all optional flue components and kits can be found in the Baxi Gas Central Heating Boilers Installers Guide 7 Instructions for guidance and fitting are included in each kit where appropriate 7 13 Extensions Additional Elbows 1 The method of connecting any flue extensions or additional elbows is the same as that for connecting the standard flue and 90 elbow as described in Section 8 3 2 If ...

Page 18: ...k that will be behind the boiler including the pressure relief discharge pipe see section 6 7 and components and pipework of the domestic hot water Unvented Kit 8 2 Flushing 1 Connect a tube to the central heating flow or return pipe 2 Flush thoroughly see Section 6 2 of System Details 3 The Baxi Combi filling loop kit can be used to flush the system IMPORTANT Do not use any safety valves to flush...

Page 19: ...ct the system pipe work as described in Section 8 5 8 4 Left Side and Vertical Flue To route the flue to either the left hand side or vertically it is necessary to use a 0 25m flue extension kit Part No 248189 A horizontal flue kit Part No 247719 or 90 flue elbow kit Part No 247725 and vertical flue terminal kit Part No 246140 will also be required Any other extensions or bends can also be purchas...

Page 20: ...he 22mm copper elbows to the CH flow and CH return taps and connect them to the system pipework Complete the soldered joints 4 Loosely fit the 15mm copper elbows to the DHW flow and cold water inlet adaptors and connect them to the system pipework Complete the soldered joints 5 Connect the remaining isolating cock to the gas supply extension piece and loosely fit the remaining 22mm copper elbow to...

Page 21: ...dish Fig 33 1 The tundish must be within 500mm of the temperature pressure relief valve when viewed in a horizontal plane 2 Downstream from the tundish the discharge pipe must fall vertically for a minimum of 300mm The discharge pipe must fall continuously over the entire length from temperature pressure relief valve to final discharge point 3 The discharge from the D H W expansion vessel may join...

Page 22: ...here discharges from safety devices may not be apparent i e in dwellings occupied by blind infirm or disabled people consideration should be given to the installation of an electronically operated device to warn when discharge takes place Note The discharge will consist of scalding water and steam Asphalt roofing felt and non metallic rainwater goods may be damaged by such discharges 2 See Figs 33...

Page 23: ...t be connected to terminal 2 NOTE If the room thermostat being used incorporates an anticipator it must be wired as shown in Fig 35a IMPORTANT The external control MUST be suitable for 230V switching 9 If the optional integral timer is to be used it should be fitted at this point Refer to the instructions supplied with the timer NOTE An external frost thermostat cannot be used with the integral ti...

Page 24: ... hot water temperature control to maximum and the selector switch to the OFF position Fig 39 Draw off all hot water to ensure that the store is cold 3 Slacken the pressure test point sealing screw and connect a pressure gauge Disconnect the sensing pipe from the spigot adjacent to the pressure test point Fig 40B 4 Turn the selector switch to the Domestic Hot Water position and open a hot water tap...

Page 25: ...Record Log Book that are relevant to the appliance and installation The details of the Log Book will be required in the event of any warranty work The Log Book must be handed to the user for safe keeping and each subsequent regular service visit recorded 5 Instruct the user in the operation of the boiler controls Hand over the User s Operating Installation and Servicing Instructions and the Log Bo...

Page 26: ... of the outercase front panel forwards Draw the panel upwards to disengage it from the locating lugs Fig 43 6 Undo the screws securing the combustion box front panel Remove the panel Fig 44 7 Undo the screws securing the combustion box inner panel Remove the panel and examine the insulation piece Fig 44 8 At the lower right of the combustion box undo the nut connecting the burner feed pipe to the ...

Page 27: ... annual basis but if problems are experienced with pressure the cartridge should be cleaned Cleaning The Cartridge 15 Turn off the mains water supply Unscrew the cartridge from the the valve body and rinse thoroughly in clean water Fig 48 16 Check the primary system pressure vessel charge and system pressure and the d h w pressure vessel charge Repressurise as necessary 17 Turn the heads of the te...

Page 28: ... is the same 1 Note the position of the wires and pipes on the pressure switch and remove them Note the position of the fan wires and disconnect them Fig 50 2 Roll the flue seal back over itself onto the adaptor spigot Fig 51 3 Undo the screws securing the fan mounting plate to the hood Draw the fan and plate assembly out of the boiler Fig 50 4 Remove the fan securing screws and separate the mount...

Page 29: ... reassemble in reverse order 11 5 Injectors Fig 54 1 Remove the burner as described in section 11 3 and undo the screws securing the injector manifold to the burner assembly and remove the manifold 2 Unscrew and replace injectors as required and reassemble in reverse order 11 6 Gas Valve Fig 55 1 Disconnect the wires from the valve modulator and the sensing pipe and earth wire from the valve body ...

Page 30: ...m the wiring loom and ease the grommet out of the electrical box 3 Hinge the facia cover panel down Remove the facia securing screws and allow the facia to hinge down Disconnect the multi pin plug from terminal M11 on the main P C B and remove the cable ties from the sleeve 4 Pull the storage cylinder upper insulation foam to one side and remove the cable tie retaining the sensor in the storage cy...

Page 31: ...e lower right hand side 6 Allow the heat exchanger to drop slightly and ease it forwards out of the combustion box taking care not to damage the side insulation pieces 7 Pull the flow pipe off the left hand heat exchanger spigot Slacken the grub screw in the return pipe boss and pull it off the right hand spigot 8 Engage the flow and return pipes on the spigots of the new heat exchanger 9 Identify...

Page 32: ...e combustion box noting it s orientation 3 It is necessary to remove both side pieces to replace the rear piece Note the orientation of the rear piece and remove it 4 When fitting the new rear piece ensure that it locates behind the burner end blade 5 Refit the side pieces ensuring that they are not abraded against the combustion box side panels captive nuts etc Completion Carefully clean away any...

Page 33: ...control panel 2 Reassemble in reverse order Ignition Sequence PCB 1 Note the position of each plug and connector and remove them Pull the earth wire off the earth grounding strip 2 Undo the PCB securing screws and remove the board 3 Reassemble in reverse order Suppressor IMPORTANT The new suppressor must be wired as shown to ensure correct operation of the boiler 1 Remove the outercase top panel a...

Page 34: ...fit the control knobs and adjust them to their previously noted settings Reassemble in reverse order Flame Failure Reset Button 1 Note the position of the wires and remove them 2 Depress the retaining barbs on the body of the reset button and draw it through the facia 3 Fit the new button to the facia connect the wires and reassemble in reverse order Temperature Gauge Figs 65 66 1 Remove the outer...

Page 35: ...ully remove the grommet over the multi pin plug and earth lead 6 Slacken the screw securing the valve operating head cover Pull the cover off 7 Undo the two screws retaining the operating head to the valve body Draw the head upwards to separate it from the body Remove it and the wiring from the boiler 8 Fit the new head to the valve body and route the wiring to the electrical box Feed the multi pi...

Page 36: ...6 Carefully remove the grommet over the multi pin plug and earth lead 7 Slacken the screws securing each washer and pipe flange to the valve Rotate the washers and disengage them from the screws 8 Undo the nut on the storage cylinder feed pipe Disconnect the flange from the diverter valve outlet port and remove the pipe 9 Undo the nuts on the central heating flow return and pressure relief pipes a...

Page 37: ...new vessel locating the lower flange in the retaining clips on the boiler base plate 6 Reassemble in reverse order and repressurise the system 11 17 Storage Cylinder Temperature Pressure Relief Valve Figs 75 76 1 Turn off the mains water supply and draw off any residual from the domestic hot water system Drain the domestic hot water storage cylinder 2 Undo the nut connecting the discharge pipe to ...

Page 38: ...r noting their position 3 Connect the wiring to the new head and set the pump speed to 3 Using new sealing washers fit the new pump fit the air vent to the pump body and reassemble in reverse order Repressurise the system 11 20 Automatic Air Vent Figs 78 80 1 Isolate the central heating system and drain the boiler primary circuit 2 Undo the screws securing the combustion box front panel Remove the...

Page 39: ...the the valve body and discard 3 Reassemble in reverse order 11 22 Expansion Relief Valve Cartridge Figs 81 83 1 Turn off the mains water supply and drain down the domestic hot water storage cylinder 2 Unscrew the cartridge from the the valve body and discard 3 Reassemble in reverse order Reducing Valve Expansion Relief Valve Expansion Relief Valve Cartridge Reducing Valve Cartridge Fig 82 Fig 81 ...

Page 40: ...5 54 53 M11 49 50 51 52 Selector Switch FA1 FA2 FA3 FA4 M6 20 21 22 16 M5 M7 17 24 25 26 27 28 29 30 Differential Water Flow Switch Overheat Thermostat M1 1 2 M2 15 16 17 18 19 M3 7 6 5 M6 23 22 21 20 19 18 M1 1 2 3 4 5 6 7 8 M10 48 47 46 45 M2 3 4 M4 8 9 10 11 12 13 14 15 M3 7 8 9 11 12 13 14 10 M1 1 2 3 4 5 M4 bk b g y br bk b bk b b br b br b br CH Control Knob DHW Control Knob br b b br bk bk ...

Page 41: ... at ignition electrodes for up to 10 seconds Go to section A Electrical supply at neon PCB Go to section B Go to section C Go to section J Go to section D Go to section E Go to section H Press to reset Go to section F Go to section I Go to section G Fan stops Replace main PCB Pump continues for 3 minutes Replace 3 way valve Operation sequence correct Boiler operates correctly C H remains cold Chec...

Page 42: ...E Go to section H Press to reset Go to section F Go to section I Go to section G Burner goes out Fan stops Pump continues for 3 minutes Operation sequence correct Safety Thermostat neon illuminated Press white reset button If neon stays illuminated or If boiler requires regular resetting investigation is necessary neon illuminated If still illuminated go to section K Burner extinguishes after 10 s...

Page 43: ...cross primary flow microswitch and main PCB M7 connector terminals 24 25 Replace microswitch 1 NO NO DHW primary temp sensor faulty cold resistance approx 11K ohms resistance reduces with increase in temp Replace sensor 2 YES Fan connections correct at fan and ignition PCB Ignition PCB M2 connector is 230V across terminals 17 18 Fan jammed or faulty winding Replace ignition PCB Replace fan YES 3 D...

Page 44: ... 20V DC across terminals 49 50 YES Replace ignition PCB YES YES YES NO H Verify in the mains input terminal block L is Live 230V and N is Neutral 0V I Check terminal 1 on reset button is in connection with ignition PCB M1 terminal 4 Check terminal 3 on reset button is in connection with ignition PCB M1 terminal 5 Continuity across terminals 1 and 3 on reset button when pressed between white and re...

Page 45: ...r Vent 248461 140 E59 897 Gas Valve 247392 102 Diverter Valve 3 Port Valve 248653 169 Pressure Gauge 248670 92 Safety Valve 3bar 248650 274 E59 948 Cartridge Pressure Reducing Valve 247403 275 E60 000 Cartridge Expansion Relief Valve 247404 79 E59 881 Storage Temp Pressure Relief Valve 247405 32 Heat Exchanger 248633 35 Expansion Vessel 248634 44 E03 569 Burner Injector 1 18mm NG 247439 73 41 79 3...

Page 46: ... Ignition 247385 314 Electrode Lead Sensing 248710 342 E60 098 Microswitch Loom 247453 135 Limit Thermostat O Heat 248656 131 Temperature Sensor 248655 172 379 764 Suppresor 247397 154 Main PCB 248672 155 Ignition PCB 248673 156 E59 912 Neon PCB 247400 171 343 718 Relay PCB 247401 315 Storage Cylinder Sensor 248711 155 171 59 314 131 342 65 172 154 315 156 135 ...

Page 47: ...r the domestic heating market Gas Central Heating Boilers Wall Floor and Fireside models Independent Gas Fires Renewal Firefronts Gas Wall Heaters Solid Fuel Fires If you require information on any of these products please write telephone or fax to the Sales Department ...

Page 48: ...Baxi UK Limited Brownedge Road Bamber Bridge Preston Lancashire PR5 6SN www baxi com After Sales Service 08706 096 096 Technical Enquiries 08706 049 049 Comp No 248660 Iss 4 5 02 921 787 3 ...

Reviews: