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This document is stored and maintained electronically by 

 

Service. All printed copies not bearing this statement in RED are deemed “uncontrolled”

 

 
 
 
 
 
 

SERVICE INSTRUCTIONS 

Rheem 27 Water Star   

Continuous Flow Water Heater with Auxiliary Hot 

Water Storage Tank

 

TM061 

 

 

 

First Issued: Nov 10     

Revision A 

Issued: Aug 13   

 

 

 

 

 

Rheem 

 

  874W27 

 

 

 

 
 

 

 

Summary of Contents for 874W27NF

Page 1: ...Service All printed copies not bearing this statement in RED are deemed uncontrolled SERVICE INSTRUCTIONS Rheem 27 Water Star Continuous Flow Water Heater with Auxiliary Hot Water Storage Tank TM061 F...

Page 2: ...YSTEM 12 TEMPERING VALVES 12 MAINTENANCE INFORMATION 13 OPERATIONAL FLOW CHARTS 16 ERROR CODES 19 THERMISTOR RESISTANCE CHART 22 FAULT FINDING 22 FAULT DIAGNOSIS SEQUENCE 23 POWER SUPPLY FAULT FINDING...

Page 3: ...ater heater with an electric boosted auxiliary hot water storage tank in the minimum of time Safety precautions or areas where extra care should be observed when conducting tests outlined in this serv...

Page 4: ...The identification numbers are designed to convey detailed information about the water heater to which it is attached The model number consists of 6 digits and up to 3 letters 87 4 W 27 N F Brand 87...

Page 5: ...dia mm 16 x 2 05 16 x 1 25 Burner Test Point Pressure kPa Min 0 193 0 277 Max 0 905 1 430 Min Inlet Gas Pressure kPa 1 13 2 75 Max Inlet Gas Pressure kPa 3 5 Storage Tank Relief Valve Setting kPa 100...

Page 6: ...11 10 REV A Issued 08 13 This document is stored and maintained electronically by Service All printed copies not bearing this statement in RED are deemed uncontrolled WIRING DIAGRAM A wiring diagram...

Page 7: ...t the preset outlet temperature setting 1 Remove the front cover from the water heater 2 Switch dip switches 3 and 4 to the ON up position on the DIP1 set of dip switches on the PCB 3 The current pres...

Page 8: ...ime the Igniter 17 starts sparking continuously and ignites the gas at the Burner 16 4 Hot water delivery from the auxiliary hot water storage tank will continue until the gas heater has achieved igni...

Page 9: ...ced but low enough to maximise the heat exchanger life The PCB activates the water bypass control motor based on the heat exchanger temperature and the selected outlet water temperature ANTI FROST HEA...

Page 10: ...onic control of gas pressure supplied to burner injectors Flame Rod Safety device that detects the presence of flame Igniter Spark igniter that lights the main burner Ignition is by means of a high vo...

Page 11: ...tion chamber to the flue way terminal Flue Way Terminal An exhaust hood made from 0 5 mm thick stainless steel sheet that projects through a slot in the upper part of the appliance front cover and dir...

Page 12: ...cause scalding It is necessary and we recommend that a temperature limiting device be fitted between an 874W27 series water heater and the hot water outlets in any ablution and public areas such as a...

Page 13: ...ull D Total combustion starts X 100 Total combustion operations since last error X 100 Null H Total combustion period X 1000 hrs Total combustion period since last error X 1 000 hours Null J Total com...

Page 14: ...ote controller 2 Restore power supply and ensure the remote controller is turned off 3 Press the temperature increase and decrease buttons simultaneously for 3 seconds until an audible beep is heard 4...

Page 15: ...sis charts the component s or fault can be quickly identified and tested using the diagnostic procedures outlined in this manual Notes and Abbreviations used in the Operational Flow Charts P G F R Val...

Page 16: ...emote controller display on On Off lamp Off On Off lamp On Fan On Fan Off 10 seconds later 5 14 Flashing Over heat limiter failure YES B Bath fill operation Water Flow Sensor off Hot water tap closed...

Page 17: ...shing 52 Flashing NO NO YES Outlet water temp exceeded 97 C for more than 15 seconds 15 Flashing Water inlet thermistor disconnected Outlet water temperature too high Heat Exchange outlet temp too low...

Page 18: ...at minimum I U I off S V 1 3 SV1 3 failure 80 Flashing 8 seconds later NO G I S V SV0 failure 51 Flashing G I S V SVO off S V 1 3 SV1 3 off P G F R Valve off Fan off YES Abnormal combustion NO 99 Fla...

Page 19: ...pliance is properly grounded Check gas solenoid valves for open or short circuits Check power supply for proper voltage and voltage drops Disconnect and re connect all wiring harnesses on unit and PCB...

Page 20: ...blocking flame at flame rod Check all wiring to flame rod for damage Check flame rod for proper voltage Remove flame rod and check clean with steel wool 76 Communication Fault with Remote Control Onl...

Page 21: ...BK3 Hot water outlet thermistor 17 P BL7 BK3 Ambient air thermistor 8 U W1 GND 0 3 100VAC Flame rod not detecting flame 14 1 100VAC Flame rod detecting flame 9 P R1 BK2 1 5 14 VDC PGFR Proportional G...

Page 22: ...225 89 1 077 15 12 583 40 4 905 65 2 157 90 1 048 16 12 086 41 4 736 66 2 092 91 1 02 17 11 611 42 4 574 67 2 029 92 0 993 18 11 157 43 4 418 68 1 968 93 0 966 19 10 723 44 4 269 69 1 91 94 0 941 20 1...

Page 23: ...ot tap NO Did the fan commence operation Follow the No Error Code Fault Finding flow chart NO Is an error code displayed YES Follow the fault finding flow chart for the error code displayed YES Follow...

Page 24: ...open circuit replace NO Is 144 192VDC present at terminal I on control PCB TEST 3 YES NO YES Replace Control PCB Rectify wiring and fully insert all multi pin connectors NO Are multi pin connectors pl...

Page 25: ...5A fuse Resistance should be 0 ohms Test 3 Test 4 Using a multimeter set on the DC volts scale measure the voltage between red and grey wires at terminal I on the control PCB Normal voltage is between...

Page 26: ...the PCB assembly NO YES YES Replace the water flow sensor NO YES 874W Series models are not suitable for use as in series gas boosters NO Free the flow sensor turbine YES Is the unit used as an in se...

Page 27: ...g Using a multimeter set on the DC volts scale measure the voltage between 1 Brown and 2 Black at terminal S on the control PCB Normal voltage should be between DC2 5V Test 7 Remove the flow sensor tu...

Page 28: ...all air from gas lines 3 Ensure appliance is properly earthed 4 Ensure gas line meter and regulator are sized properly 5 Ensure gas type and gas pressure to the unit is correct Error Code 11 Scenario...

Page 29: ...roportional gas valve TEST 10 YES NO YES Is the resistance of the proportional gas valve correct TEST 12 YES NO YES Fan is operating igniter does spark main burner does not ignite Error Code 11 Scenar...

Page 30: ...C volts scale measure the voltage with multi pin connector plugged into terminal W on control PCB Using a multimeter set on the kilo ohms scale measure the resistance with multi pin connector unplugge...

Page 31: ...on the ohms scale measure the resistance between 1 Red and 2 Black at terminal P whilst unplugged from the PCB Normal resistance is between 40 ohms and 80 ohms Test 13 Test 14 Conduct test with flame...

Page 32: ...ses 1 Bleed all air from gas lines 2 Ensure appliance is properly earthed 3 Ensure gas line meter and regulator are sized properly 4 Ensure gas type and gas pressure is correct Error Code 12 Is the in...

Page 33: ...connector at terminal T on control PCB properly connected YES Fully insert multi pin connector into terminal T on control PCB NO Error Code 15 Boiling Safety Device The heat exchanger is too hot At a...

Page 34: ...16 The gas booster should not operate with an inlet temperature in excess of 58o C Error 16 will occur if the unit heats the water to 20o C above the set point 3o C eg 60 20 3 77o C Is the unit used...

Page 35: ...4 Release the Min Max button Is the Min or Max button depressed TEST 16 NO YES Replace the control PCB Error Code 29 Heat exchanger outlet temperature is too low Error Code 29 Measure the hot water ou...

Page 36: ...rmistor 32 Heat exchanger thermistor 33 Hot water outlet thermistor 34 Ambient air thermistor YES YES Is the wiring between control PCB and thermistor intact Is the thermistor multi pin connector full...

Page 37: ...control Replace gas valve assembly NO Does the flame extinguish completely after shut down Does flame detection maintenance information 0y indicate 01 YES Clean or replace the flame rod electrode NO R...

Page 38: ...Error Code 61 Combustion fan failure Error Code 61 Display maintenance information 6y Manually operate fan by pressing the MAX SW2 button Is the correct fan speed indicated Refer to fan speed chart C...

Page 39: ...1 Check wiring if intact replace the control PCB NO YES Replace water volume control assembly Is the voltage to the water volume control motor normal TEST 20 Check wiring if intact replace the control...

Page 40: ...t by pulse counter of not less than 4800 pulses per minute Test 20 21 Test 22 23 Conduct test with water flowing Using a multimeter set on the DC volts scale measure the voltage at connector N whilst...

Page 41: ...re multi pin plug is fully inserted NO Error Code 72 Follow the same procedure as used in Error Code 51 Error Code 76 Communication Fault with Remote Temperature Control Error Code 76 Will the unit op...

Page 42: ...d Error Code 79 Fan Motor Current fault Error Code 79 Is error code 79 redisplayed YES Isolate power remove the J connector from the control PCB and restore power Replace the control PCB Isolate power...

Page 43: ...type connector fitted to suit the model and gas type NO Isolate power and remove power cord from GPO for 10 seconds Restore power Install the correct gas type connector to suit the model and gas type...

Page 44: ...xchanger Drain and flush the exchanger Warning Code P1 Water flow rate is less than minimum for main burner ignition The unit must have 2 5 litres per minute before the main burner will light or susta...

Page 45: ...eplace thermostat Replace element Does the heating unit have the correct resistance TEST 27 Did the thermostat contacts close TEST 26 Is the water in the tank at least 12 lower than the thermostat set...

Page 46: ...With the water heater plugged in and switched on use a multimeter on the AC volts scale and measure between active and neutral on the thermostat Normal voltage is 240 volts Test 25 Using a multimeter...

Page 47: ...ly by Service All printed copies not bearing this statement in RED are deemed uncontrolled Component Test 27 Test 27 Disconnect element wires from terminals 2 and 4 of the thermostat Using a multimete...

Page 48: ...shown on the LED display Note The adjuster button must be held down through steps 8 to 11 9 Press and hold the MIN button and observe the reading on the manometer 10 Release the MIN button when the p...

Page 49: ...installed Fitment of an incorrect PCB may result in unit malfunction or a breach of the approval of the unit Power Supply PCB Procedure 3 1 Isolate power supply 2 Remove the front cover and control P...

Page 50: ...ix screws that retain the manifold assembly to the gas valve and burner assembly one at top left hand side and one at top right hand side of manifold and four at gas valve assembly on bottom right han...

Page 51: ...edure 1 3 Undo cord clamp screw located on bottom left hand side of PCB and remove clamp 4 Disconnect Earth connection at PCB housing 5 Disconnect the power cable wiring loom plug and withdraw power c...

Page 52: ...rol Assembly Procedure 12 Do not attempt to dismantle the servomotor this is factory calibrated Adjustments will render the water heater either inoperable or cause incorrect water temperature delivery...

Page 53: ...trol assembly by removing the retaining screw 8 Remove water volume control assembly from heater cabinet 9 Reassemble in reverse order of above Ensure an o ring is fitted to each of the connections on...

Page 54: ...bove Ambient Air Thermistor Procedure 17 1 Isolate power supply 2 Remove front cover control PCB and power supply PCB Refer to procedures 1 2 and 3 3 Locate the ambient air thermistor and remove retai...

Page 55: ...wo screws from the hot water outlet flange to release the hot water outlet anti frost heater 5 Remove the screw from the cold water inlet connection to release the cold water inlet anti frost heater 6...

Page 56: ...5 Reassemble in reverse order of above 6 Test for gas leaks using soapy water solution 7 Check for water leaks Over Heat Limiter Assembly Procedure 23 Replacement of the overheat limiter requires rem...

Page 57: ...asing the T PR valve Leave valve open 6 Disconnect the transfer pipe from the inlet of the hot water storage tank At this point the contents of the 2 6L hot water storage tank will be relieved through...

Page 58: ...release the transfer valve 8 Reassemble in reverse order of above 9 Restore the water supply and check for leaks 10 Purge air from the system through hot taps 11 Restore the power supply to the water...

Page 59: ...quick connect fitting from the outlet of the T PR valve 9 Unscrew the T PR valve from the top of the cylinder 10 Confirm the replacement T PR valve is the correct rating and refit using thread tape 1...

Page 60: ...from the earth nest at bottom left hand side of heater cabinet 6 Undo the packing straps and remove the front polystyrene insulation to expose the hot water storage tank 7 Disconnect the red element w...

Page 61: ...ter Star Service Instructions Document N TM061 REV Details of change D O I Service instructions issued 11 10 A Exploded views and replacement parts listing removed Now form part of Spare parts manual...

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