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Worcester Highflow 400 BF, Installation And Servicing Instructions, Page: 36 / 44

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Worcester Highflow 400 BF Installation And Servicing Instructions Download Page 36

36

OFF

OFF

OFF

No lights and no functions

A

OFF

No green light. All functions o.k and red lights o.k.

B

ON

OFF

No CH light and no CH function. HW function o.k.

C

ON

OFF

No HW light and no HW function. CH function o.k.

D

ON

Serious temperature fault in CH or HW mode.

E

ON

SLOW FLASH

Ignition sequence failure lockout. Pilot gas not detected after 2 minutes

F

(reset using CH temperature control).

ON

FAST FLASH

Sensor failure.

G

ON

SLOW FLASH SLOW FLASH

Safety Temperature Limiter lockout  (reset using CH temperature control).

H

ON

ALTERNATE FLASH

Tank overheat lockout (call Service Engineer).

I

ON

FAST FLASH

FAST FLASH

Diverter spillage trip (OF only)

J

Other faults

K

17. Fault Finding

GREEN 

LIGHT

RED CH

LIGHT

RED HW

LIGHT

FAILURE DESCRIPTION

Light Situation During Fault

CH LIGHT

(Red)

HW LIGHT

(Red)

POWER LIGHT

(Green)

CH CONTROL

HW CONTROL

FAIL

POINT

SLOW FLASH   

is once per second

FAST FLASH

is five times per second

NOTE: There is no mains supply isolating switch on the appliance

Note: 

This fault-finding information is for guidance only. Worcester Heat Systems cannot be held responsible for costs incurred by

persons not deemed to be competent.
The electronic control system for this boiler incorporates three lights on the facia. These are used to show normal operating status. But as
a secondary function, by flashing, they can also be used to help provide fault diagnostics. Therefore, with individual or groups of lights
being permanently off, on or flashing, every normal fault can be identified.
To use the fault finding system, select a box below which represents the light situation during your fault. Then refer to the appropriate fail
point. This fault-finding system assumes that the appliance has been operating correctly until the time of failure and not an installation
error..

PRELIMINARY CHECKS

Preliminary electrical system checks are the first electrical checks to be carried out during a fault-finding procedure. On completion of
the Service/Fault-Finding task which has required the breaking and remaking of electrical connections, check (a) EARTH CONTINUITY,
(b) SHORT CIRCUIT CHECK, (c) POLARITY and (d) RESISTANCE TO EARTH.

Summary of Contents for Highflow 400 BF

Page 1: ...utomatic Modulating Control Domestic Hot Water and Central Heating Minimum 8 8 kW DHW 11 0 kW CH Maximum 24 0 kW IMPORTANT THIS APPLIANCE IS FOR USE WITH NATURAL GAS ONLY THESE INSTRUCTIONS APPLY IN THE UK ONLY THESE INSTRUCTIONS ARE TO BE LEFT WITH THE USER OR AT THE GAS METER This appliance must be installed by a competent person in accordance with the Gas Safety Installation and Use Regulations...

Page 2: ... installations 2 1 GENERAL INFORMATION 2 1 1 The appliance is set to provide the maximum output of 24kW to the domestic hot water and to the central heating 2 1 2 The domestic water section of the appliance is suitable for mains water pressures of up to 10bar 2 2 ELECTRICAL SUPPLY Mains supply 230V 50 Hz 95 Watts External fuse 3A Internal fuses T 2A F1 and T 1A F2 2 3 GAS SUPPLY Check the data pla...

Page 3: ... GC No 393 547 is available from Tower Flue Components Vale Rise Tonbridge TN9 1TB The standard horizontal flue assembly length is from 229mm to 407mm Extended flue lengths up to 610mm are available using the optional extended flue kit Do not allow the flue terminal fitted to the outside wall to become obstructed or damaged 2 7 CONTROLS The electronic control system via the gas valve modulates the...

Page 4: ...e fitted adjacent to the boiler in the cold water supply pipe 2 10 SAFETY CONSIDERATIONS The appliance must not be operated in a waterless condition The appliance must not be operated with the boiler inner casing cover removed Work must not be carried out on the appliance without the gas and electricity supplies being turned off Checks must be made to ensure that where applicable the ventilation o...

Page 5: ...RNER PRESSURE mbar 14 1 GAS RATE m3 h 2 80 MIN OUTPUT CH kW 11 0 MIN INPUT CH net kW 12 9 BURNER PRESSURE mbar 3 2 GAS RATE m3 h 1 33 MIN OUTPUT DHW kW 8 8 MIN INPUT DHW net kW 10 4 BURNER PRESSURE mbar 2 2 GAS RATE m3 h 1 10 Table 1 BOILER ADJUSTED FOR G20 Natural Gas PUMP HEAD BOILER OUTPUT HEAD MIN FLOW RATE FLOW RETURN DIFFERENTIAL kW Metres L min C 11 0 6 1 11 5 11 C 24 0 5 0 16 5 21 C Table ...

Page 6: ... 11 0 CH to 24 0kW Modulating MAXIMUM DOMESTIC HOT WATER FLOW RATE FROM THE APPLIANCE Nominally 18 0 l min 15 EQUIVALENT HOT WATER FLOW RATE FROM THIS APPLIANCE TO GIVE 20 l min 30 C RISE SPECIFIC RATE D FLUE PRODUCTS 11 7 gm sec FLUE PRODUCTS TEMPERATURE 140 C NOx CLASSIFICATION Class 2 SEDBUK 80 0 BAND D Table 6 Table 7 Total Length of Gas Supply Pipe metres 3 6 9 8 7 5 8 4 6 22 18 0 12 0 9 4 28...

Page 7: ...Depth 600 Cabinet Width 300 5 Space required in front for installation and servicing Space required for installation Space required for servicing Surface may be fixed after installation A gap of 10mm is required above the appliance Space required under fixed surface Space required for installation Space required left hand side for installation Space required each side for servicing Floor Level 450...

Page 8: ... jurisdiction of Building Control should adhere to the increased clearances 5 2 TERMINAL POSITION See Fig 4 5 3 The terminal must not cause an obstruction nor the discharge a nuisance 5 4 If the terminal is fitted within 850mm of a plastic or painted gutter or within 450mm of painted eaves then an aluminium shield at least 750mm long should be fitted to the underside of the gutter or painted surfa...

Page 9: ... head is greater than 5m 7a 6 With an initial system pressure of 0 5 bar a system capacity of about 104 litres can be accommodated Refer to BS 7074 Pt 1 for more information 7a 7 The filling point must be at low level See Fig 6 7a 8 Water loss must be replaced The connection should be made in the central heating return as close to the appliance as possible See Fig 5 7a 9 The make up vessel must be...

Page 10: ...ere is normally no need for water treatment to prevent scale accumulation In exceptional circumstances a device to prevent scale formation can be fitted 8 13 Installation of a scale inhibitor assembly should be in accordance with the requirements of the local Water Company An isolating valve to allow servicing should be fitted 8 14 The temporary water hardness can be determined using a standard te...

Page 11: ...cable through the top hole at the rear of the electrical box Do not omit the cable clamp For access to the electrical box refer to Section 15 10 3 The appliance must be earthed 10 4 The wiring between the appliance and the electricity supply shall comply with current IEE wiring regulations and any local regulations which apply for fixed wiring to a stationary appliance NB It must be possible to co...

Page 12: ...r Tank Sensor Overheat Thermostat System Thermostat TTB Thermostat OF only Flow Turbine INPUTS OUTPUTS INDICATORS Convert AC to Low Voltage DC MICROPROCESSOR ELECTRONICS Safety Low Voltage Mains ON Green CH Light Red DHW Light Red Heating demand from Programmer or link L to CH Hot water demand from Programmer or link L to DHW X2 PIN CH X2 PIN DHW X3 PIN Rs X3 PIN N X3 PIN R R Frost Thermostat if f...

Page 13: ...Sections 4 and 5 Also refer to fig 2 Do not place the appliance in its final position at this stage 11 2 FLUE PREPARATION Having decided upon the most suitable position for the appliance the hole for the balanced flue assembly must now be marked on the wall From the dimensions given in Fig 13 carefully mark the wall to position the hole for the balanced flue assembly Cut a hole in the wall 380mm w...

Page 14: ... 90 into the Service Position Lodge in the Service Position on the outer locations See Fig 11 iv Unscrew the two screws behind the control panel securing the cabinet top panel See Fig 11 v Lower the facia and control box to the fully extended position Ease the cabinet top panel forwards approximately 20mm and lift clear of the appliance See Fig 11 Return the facia and control box to the Service Po...

Page 15: ...ept balanced flue assembly This dimension may vary depending on whether any floor covering is removed and or an insulating sheet is placed between the appliance and the floor Inside plaster Wall thickness W to include any surface finish inside or outside W 280 300 600 380 347 5 40 56 247 570 280 555 555 860 Fig 13 Balanced flue appliance wall preparation 245mm 9 6in 345mm 13 5in W Fig 14 Air duct ...

Page 16: ...s Inner casing Lowered expansion vessel Floor level Drill and plug wall Secure terminal to wall with four screws Telescopic air duct Flue hood fixing screws 10mm 0 4in diameter continuous seam of silicone sealant all around Air duct spigot located on the rear of the inner casing Part front view of inner casing with front cover removed Flue duct fixing screws Fig 15 Arrangement of balanced flue and...

Page 17: ...rn valve 22 Hot water sensor 23 Mains cold water inlet valve Fig 18 Discharge pipe connection for sealed system Base plate Rear view of appliance Cabinet side panel Pressure relief drain connection Discharge pipe must be 15mm copper fall continuously throughout its length and discharge to a safe visible position Remove securing clip Ease pump head forwards off the O ring seals Remove securing clip...

Page 18: ...t water and central heating load of 24 kW The appliance automatically modulates to satisfy lower heat loads Domestic Hot Water Circuit Confirm that the mains water supply has been flushed out at installation If not it will be necessary to disconnect the cold water inlet pipe from the appliance and thoroughly flush Central Heating System Flush the system before starting to commission the appliance ...

Page 19: ...ssure See Fig 16 If the pressure indicated on the pressure gauge is greater than 2 5 bar when operating at the maximum central heating temperature an extra expansion vessel must be fitted to the system as close to the appliance central heating return connection as possible The appliance as despatched can accommodate a system volume of about 104 litres Refer to BS 7074 Part 1 If the system volume i...

Page 20: ...om cold it will take about 12 minutes for the heatbank to be satisfied before the central heating system will receive heat IMPORTANT The complete system must be checked for water leaks Should any leaks be found they must be rectified before proceeding further Set the temperature controls to OFF or if a programmer is fitted switch to OFF Switch electrical supply off at the mains Check for the corre...

Page 21: ...et Remove the pilot injector from the pilot bracket See Figs 16 and 23 14 3 SERVICING OF COMPONENTS Clean the Burner Brush the blade tops and mixing tube with a soft brush and check that all the flame ports are clear Remove any blockages with a non metallic brush Clean the Main Burner Injector Inspect the main burner injector located at the rear of the inner casing Clean with a soft brush Do not u...

Page 22: ...k electrode lead Pilot pipe union nut Sealing grommets Pilot bracket and fixing screws 2 Thermostat fixing Flue hood Flue hood fixing screws 2 Combustion chamber cover Combustion chamber cover fixing screws 4 Pilot pipe Safety Temperature Limiter Water to water heat exchanger Flame sense electrode CH Primary Sensor Spark electrode earth lead Spark electrode ...

Page 23: ...n chamber Remove the access cover in the left hand side of the combustion chamber held in position with one screw Unscrew the front and rear heat exchanger union connections Lift the heat exchanger off the right hand side of the combustion chamber support and clear of the union connections Remove the heat exchanger clear of the inner casing CAUTION There will be a small quantity of water remaining...

Page 24: ...er the expansion vessel and remove the inner casing cover as described in Section 14 2 a b c and d RemovethecombustionchambercoverasdescribedinSections14 2g Unscrew the two screws securing the pilot burner to the main burner Ease the pilot burner forwards sufficiently to allow access Unscrew and withdraw the flame sense electrode Remove the facia as described in Section 15 1 Carefully pull the lea...

Page 25: ...mostat pocket out of the top manifold and clear of the appliance The water filter is located inside the top manifold Remove the filter and clean or replace Reassemble the appliance in the reverse order using a new O ring seal Ensure that the screws are correctly located and tightened 14 Tank Sensor See Fig 28 Surface sensor with horizontal 6 3mm tabs Check that the electricity supply to the applia...

Page 26: ...ng seals Fit a replacement pump in the reverse order taking care to ensure the securing clips are properly entered into the slots and not scoring the O rings on entry A smear of lubricant on each O ring will ease the re assembly Check the pump head is set to maximum The pump head is a Grundfos 15 60 A replacement head may be transferred to the special body Take care not to mark the mating surfaces...

Page 27: ...n Section 15 2 CAUTION The weight of the water to water heat exchanger is 2 kg approx A quantity of water will remain in the heat exchanger and pipework Follow the procedure as described in Section 15 2 Remove the circulating pump as described in Section 15 3 18 Remove the water diverter valve as described in Section 15 3 19 Note i It is not necessary to disconnect the electrical cable from these ...

Page 28: ...e front push in elbow and remove the elbow Retain the clip and push in elbow To release the rear elbow reach under the water to water heat exchanger bracket and push in fully the flat plate clamp mechanism Remove the rear push in elbow and retain Remove and discard the elbow O ring seals Replace with new O ring seals Re assemble the rear and front push in elbows Ensure the rear clamp mechanism is ...

Page 29: ...pipe downwards 10mm into slip joint in bottom manifold Ease pipe to the left to clear top manifold Ease pipe upwards 10mm approx to clear top manifold and remove O ring seal Slip joint Heating return pipe O ring seal Water to water heat exchanger Slip joint Drain pipe securing clip Bottom manifold Front view of water to water heat exchanger with manifolds in position and fixing screws numbered 6 7...

Page 30: ... tightened Locate hole in bottom manifold over internally threaded boss Replace the O ring seals Bottom manifold 1 13 9 14 2 5 6 7 8 11 12 10 Fig 36 Replacing the O ring seals in top and bottom manifolds 15 Replace O ring seals Slip joint Flow pipe shortest Flow connection Flat clip Replace O ring seals Remove screw and support bracket from gas valve Domestic drain Remove clip and ease downwards 1...

Page 31: ...the Service Position and lower the expansion vessel into the Service Position as described in Section 14 2 a b and c Drain the heating circuit as described in Section 15 2 a Unscrew the union fitting on the right hand side of the expansion vessel Remove and dispose of the sealing washer Ease the expansion vessel assembly upwards to clear the support bracket and remove from the appliance Take care ...

Page 32: ...water filter is located in the top of the housing Remove the filter clean or replace Reassemble in the reverse order and replace the sealing washer No sealing compound is required Open the mains water valve and fill the hot water circuit Reassemble the appliance in the reverse order 30 Hot Water Flow Regulator See Fig 39 Check that the electricity supply to the appliance is turned off Remove the c...

Page 33: ...rminals marked X2 Programmer Switch Undo the four nuts securing the programmer to the facia and remove Fit a new programmer in the reverse order and connect the plug at the driver board Reassemble the facia in the reverse order 33 Remote Mounted Programmer See Fig 11 Check that the electricity has been turned off and isolate the programmer Disconnect the leads from the programmer noting the alignm...

Page 34: ... valve ON 3 minute wait CH temperature 4 C below set point Pump and diverter valve energised for 3 minutes AND HW temperature control ON HW flow above 2 7 l min AND HW programmer ON or link HW flow above 9 l min HW temperature lower than set point OR HW flow below 9 l min HW temperature 4 C below set point HW light ON Pump ON AND Modulate heat input to maintain temperature set by user control 55 7...

Page 35: ...heat input if primary temperature is over 82 C or HW flow 1 to 2 7 l min Tank 8 C below set temperature Primary temperature below 90 C AND Gas valve OFF Modulate gas to set point 65 75 PUMP ONLY HW temperature control ON Draw off over 2 7 l min HW temperature control ON HW programme ON Draw off over 2 7 l min HW temperature control ON HW programme ON Tank 8 c below set point CH temperature control...

Page 36: ...he appliance Note This fault finding information is for guidance only Worcester Heat Systems cannot be held responsible for costs incurred by persons not deemed to be competent The electronic control system for this boiler incorporates three lights on the facia These are used to show normal operating status But as a secondary function by flashing they can also be used to help provide fault diagnos...

Page 37: ...d by low voltage wiring e g wiring shorts or terminals touching boiler chassis Replace fuse F2 and check wiring or replace control board Yes Correctly set or replace CH programmer or link terminals L to CH No Correctly set or replace room thermostat or link terminals Rs to RR on connector X3 Turbine may be sticking Replace flow turbine FAIL POINT D No Yes Yes No Is there a 230Vac live supply acros...

Page 38: ...h a fault investigate flue problems burner and injector Replace gas valve No Yes Central heating water cold or luke warm dur ing CH demand Suspect Measure the resistance of the diverter valve coil Is it 150 250 ohms Yes Replace diverter valve No Replace coil No Yes Diverter valve not opening Disconnect the 2 way plug from diverter valve coil Does this solve the problem Central heating water hot wh...

Page 39: ...onnector X6 If so replace control board Yes Is there a pilot flame at the pilot assembly combustion chamber cover may need to be removed to aid viewing No Remove ignitor unit from gas valve measure the resis tance across the two outer electrical pins on the gas valve Is resistance between 6kΩ Ω and 9kΩ Ω No Replace gas valve Yes Inspect pilot tube for blockage and bad mechanical connections Also c...

Page 40: ...e continuity from the contacts to the faulty sensor Yes No Yes Replace control board FAIL POINT H Primary Overheat No Yes No Rectify fault Is the boiler fully water pressurised and is all air vented Replace control board No Is there 230Vac at connector X5 pin 1 At this point it is difficult to accurately diagnose the fault Probable causes are 1 Primary sensor out of tolerance 2 Faulty gas to water...

Page 41: ...tat self resets Yes Check air gas channels in gas water heat exchanger Are they free of restrictions No Unblock rectify fault No Clean or replace heat exchanger FAIL POINT K If the boiler has developed erratic or poor performance and the above information has not satisfactorily located the fault the following information may be useful Temperature sensors These are critical to provide temperature i...

Page 42: ...3 DHW Heat Exchanger SWEP E8 18 c w O Rings 1 8 716 142 904 0 18 Water Diverter Valve Bosch c w O Rings 1 8 716 104 569 0 19 Heatbank Overheat Thermostat Elmwood 1 8 716 103 217 0 20 Safety Temperature Limiter Elmwood 1 8 716 103 216 0 21 CH Primary Sensor Elmwood 6655 9488 4 1 8 716 142 319 0 22 Tank Sensor Elmwood 1 8 716 770 425 0 23 HW Sensor Kit Elmwood 6655 9003 5 1 8 716 142 302 0 24 Progra...

Page 43: ...43 ...

Page 44: ...n the interests of continued improvement All goods sold are subject to our official Conditions of Sale a copy of which may be obtained on application PUBLICATION 8 716 115 019a 02 08 Worcester Heat Systems Limited Cotswold Way Warndon Worcester WR4 9SW Telephone 01905 754624 Fax 01905 754619 Technical Helpline 0990 266241 www worcester bosch co uk ...

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