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NFC Service Manual 125

Version 1.0

6.2.7 Main Gas Valve

1.  Turn off the gas supply to the unit.
2.  Disconnect the unit from the power supply.
3.  Turn off the water supply to the unit.
4.  Disconnect the wiring connector and remove the four screws

marked in the image below.

Figure 15

6.2.8 Water Pressure Sensor

1.  Turn off the gas supply to the unit.
2.  Turn off the 120V power supply to the unit.
3.  Turn off the water supply to the unit. Drain all water from the

appliance.

4. Disconnect the water pressure sensor wire housing.

Figure 22

5.  Pull out the water pressure sensor.
6.  Replace with new water pressure sensor.
7.  Connect the water pressure sensor wire housing.

Note

Always use proper O-rings at the water pressure valve

connection to ensure tight seals.

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Summary of Contents for NFC-175

Page 1: ...ht any appliance Do not touch any electrical switch do not use any phone in your building Immediately call your gas supplier from a neighbor s phone Follow the gas supplier s instructions If you canno...

Page 2: ...2 NFC Service Manual Version 1 0 Version Description of changes Date 1 0 First Issue December 2018 Revisions...

Page 3: ...Operation 38 4 8 5 Viewing Error History 41 4 8 6 Viewing Other System Information 41 4 8 7 Setting the Display Options 42 4 9 Accessing Advanced Menu Items 42 4 9 1 Viewing Service Information 42 4 9...

Page 4: ...4 5 2 20 353Error 105 5 2 21 407Error 106 5 2 22 421Error 107 5 2 23 434Error 108 5 2 24 439Error 109 5 2 25 441Error 110 5 2 26 445Error 111 5 2 27 515Error 112 5 2 28 517Error 113 5 2 29 594Error 11...

Page 5: ...he appliance is located in a crawl space unless the appliance is located in a detached uninhabitable garage For all residential dwellings a carbon monoxide detector must also be present on each habita...

Page 6: ...ty Service At its option Navien will replace the defective component part s or heat exchanger in accordance with the terms of this Limited Warranty if it fails in normal use and service during the App...

Page 7: ...ir openings electric service voltage wiring fusing or any other components parts or specifications Improper conversion from natural gas to LP gas or LP gas to natural gas or attempt to operate with a...

Page 8: ...of NFC 175 NFC 200 NG Natural Gas LP Propane Gas AP Air Pressure APS Air Pressure Sensor DHW Domestic Hot Water FM Fan Motor GPM Gallons Per Minute MGV Main Gas Valve RPM Revolutions Per Minute PCB P...

Page 9: ...ay can near the boiler or the venting system including the vent termination DO NOT place anything in or around the vent terminations that could obstruct the air flow in and out of the boiler such as a...

Page 10: ...explosion or asphyxiation from carbon monoxide never operate the boiler unless it is properly vented to the outside and has an adequate air supply for proper operation Be sure to inspect the vent term...

Page 11: ...Natural Gas from the factory If conversion to Propane Gas is required the conversion kit supplied with the boiler must be used Be sure to use 120 VAC 60 Hz minimum 2 A current Using abnormally high o...

Page 12: ...pairorreplaceanypartoftheboiler unless it is specifically recommended in this manual For all other service contact an authorized technician or licensed professional Improper adjustments alterations se...

Page 13: ...he heat capacity each model is divided into two types 175 and 200 Model Maximum Space Heating Input NFC 175 175 000 BTU h NFC 200 199 000 BTU h A separate heating expansion vessel is required Internal...

Page 14: ...rts lists are included in the Appendixes Intake Air Air Intake Pipe Exhaust Fan Motor Assembly Dual Venturi APS PCB Power Switch PRV Air Vent Connection Gas Pipe Mixing Chamber Igniter Flame Rod Ignit...

Page 15: ...Heat Exchanger APS Power Switch Mixing Valve 3 Way Valve Heating Return Gas Valve ASME Name Plate Mixing Chamber Intake Air Filter Flame Rod Igniter Circulation Pump Water Adjust Valve DHW Exchanger W...

Page 16: ...FC 200 18 199 183 159 95 Note 1 Ratings are the same for natural gas models converted to propane use 2 Based on U S Department of Energy DOE test procedures 3 The net AHRI water ratings shown are base...

Page 17: ...e pump used for the boiler and the performance curve Item Pump Model NFC 175 200 Internal Recirculation Pump Grundfos UPS 15 78 CIL2 Part Number 30021636A 0 5 10 15 20 25 30 0 2 4 6 8 10 12 14 16 0 2...

Page 18: ...r Consumption Less than 15 amperes Materials Casing Cold rolled carbon steel Heat Exchangers Stainless Steel Venting Exhaust 2 in or 3 in PVC CPVC approved polypropylene 2 in or 3 in Special Gas Vent...

Page 19: ...Air Vent Connection 3 4 in D Heating Supply 1 in E Heating Return 1 in F Gas Connection 3 4 in G Condensate Outlet 1 2 in H Cold Water Inlet DHW 3 4 in I Hot Water Outlet DHW 3 4 in J Auto Feeder Inl...

Page 20: ...e Heating Thermostat Used 7 OFF Unused 7 ON 8 Exhaust Temperature Control Used 8 OFF Unused 8 ON CAUTION Do not remove the front cover unless the power to the boiler is turned off or disconnected Fail...

Page 21: ...nal injury or malfunction of the boiler 4 3 Measuring the Inlet Gas Pressure WARNING The boiler cannot function properly without sufficient inlet gas pressure Measuring the inlet gas pressure should b...

Page 22: ...d then turn off the boiler 8 Unfasten the 4 latches 2 at the top and 2 at the bottom to remove the front cover and gain access to the internal components 9 Loosen the screws indicated in the figure be...

Page 23: ...0 2 230 2 080 1 950 1 840 1 630 3 in 11 300 7 780 6 250 5 350 4 740 4 290 3 950 3 670 3 450 3 260 2 890 4 in 23 100 15 900 12 700 10 900 9 660 8 760 8 050 7 490 7 030 6 640 5 890 In Cubic Feet ft3 per...

Page 24: ...m 150 ft 45 m 175 ft 53 m 200 ft 60 m 250 ft 76 m 1 2 in 291 200 160 137 122 110 101 94 89 84 74 67 62 3 4 in 608 418 336 287 255 231 212 197 185 175 155 140 129 1 in 1 150 787 632 541 480 434 400 37...

Page 25: ...covers the boiler s installation at an altitude of 0 to 10 100 ft WARNING This conversion kit must be installed by a qualified service agency in accordance with Navien s instructions and all applicab...

Page 26: ...ental damage 4 With the internal components exposed locate the gas inlet pipe and the gas valve as shown in Figure 2 Gas Valve Gas Inlet Pipe Figure 2 NFC Series Internal Components 5 Remove the clip...

Page 27: ...ING DO NOT adjust or attempt to measure gas valve outlet pressure The gas valve is factory set for the correct outlet pressure This setting is suitable for natural gas and propane requiring no field a...

Page 28: ...table above Note This unit may be installed at elevations up to 10 100 ft 3 078 m for use with natural gas and propane To use the unit at a specific altitude the DIP Switches should be set as describe...

Page 29: ...on the circuit board configures the operation status and model capacity settings 1 2 3 4 5 6 O N O N 1 2 3 4 5 6 7 8 Switch Function Setting 1 2 Operation Status Normal Operation 1 OFF 2 OFF 2 stage M...

Page 30: ...on Modes on page 48 Measure the CO2 value at low fire If the CO2 value is not within 0 5 of the value listed in Table 2 the gas valve set screw will need to be adjusted If adjustment is necessary loca...

Page 31: ...0 BTUh Conversion Kit No NAC NCH200 Inlet Gas Pressure Pression d entr e du gaz Min 8 0 to Max 13 0 in WC Figure 10 Proper Placement of Gas Conversion Labels Note The gas conversion rating plate varie...

Page 32: ...solid if the boiler is set as the Master unit in a cascade system f DHW priority Displayed when the DHW Priority feature is enabled g Space heating demand Indicates the space heating demands from the...

Page 33: ...required for the boiler s operation such as space heating and DHW supply temperatures Refer to the following table for detailed information a Back button Return to the previous menu or screen b Mode b...

Page 34: ...malfunction the boiler will operate at this set temperature Take note of the original heating temperature in case you want to restore it to the default The default space heating supply water temperat...

Page 35: ...boiler operation reset the boiler to resolve the problem Press the Back button on the front panel to reset the boiler If resetting the boiler does not solve the problem refer to the Troubleshooting s...

Page 36: ...15 Water Press Water pressure psi 4 8 Accessing Basic Menu Items In the Main Menu screen you can view the boiler s operating conditions configure the space heating and DHW temperatures and review erro...

Page 37: ...l Model type 30 Gas Fuel type NG LPG 31 Main F W Ver Main firmware version 32 Panel F W Ver Controller panel firmware version 4 8 3 Setting the Space Heating Operation To set the boiler s space heatin...

Page 38: ...he Menu button and then select 4 DHW Operation Rotate the Command dial to switch between the list items or to increase decrease setting values Press the Command dial to select an item or to confirm af...

Page 39: ...the previous screen or menu Item Description 1 DHW Set Temp Set the hot water temperature F Setting range 86 140 F 30 60 C Default 122 F 50 C 2 DHW Recirculation When only one NFC boiler is connected...

Page 40: ...using the recirculation feature in the cascade system you can choose commands in the menu to preheat according to the set DHW temperature Refer to 8 2 Cascade System Recirculation System Application...

Page 41: ...istory press the Menu button and then select 5 Error History A list of 10 recent errors are displayed on the screen with the most recent error displayed at the top of the list Rotate the Command dial...

Page 42: ...of Times Number of tenth ignition attempts 8 T Limit No of times Number of times supply return temperature limit control has activated 9 Supply Limit No of times Number of times Recirculation supply...

Page 43: ...making changes 4 9 2 Viewing Input and Output Status To view the boiler s input and output status press the Back button and the Menu button simultaneously for 3 seconds and then select 2 Input Output...

Page 44: ...oiler Pump Delay Set the space heating pump over run time Setting range 3 40 min Default 40 min Press the Back button to return to the previous screen or menu Item Description 1 Supply MIN Set point S...

Page 45: ...f the boiler operation temperature range for a set period the pump stops for 10 mins runs again for 5 mins and then repeats the cycle Item Description 18 DHW Wait Time Set the DHW wait time Setting ra...

Page 46: ...t Rotate the Command dial to switch between the parameters or to increase decrease setting values Press the Command dial to select a parameter or to confirm after making changes Press the Back button...

Page 47: ...operation The boiler pump is turned on as soon as you enter the test mode Press the Command dial to toggle the pump operation On Off Off On 3 Zone 1 Pump Test the Zone 1 pump operation The Zone 1 pump...

Page 48: ...ff On This option is available only when the Zone Pump System is active 5 Zone 3 Pump Test the Zone 3 pump operation The Zone 3 pump is turned on as soon as you enter the test mode Press the Command d...

Page 49: ...1 PWM EMI FILTER DC5V H T L_1 WD PSS SMPS Primary Secondary 3 15A System Return Thermistor Relay 4 Outdoor Thermistor INLET Thermistor Dip Switch Air Handler Output Dip Switch Relay 3 Relay 2 Relay 5...

Page 50: ...Supply Temperature Sensor 1 CNT2 CNT3 AC24VN AC24VL CNC3 LWCO AC 24V 60Hz LWCO AC24V LWCO 1 T S4 T S3 T S2 External R C THERMOSTAT1 THERMOSTAT2 CNC4 CNC5 CNC6 1 CNK1 CND1 FUSE 250V 3 15A 3WAY V V CNO...

Page 51: ...er is operating Ground Wire CNI1 1 GREEN YELLOW Check for properly grounded wire D Water Pressure Sensor CNG1 4 5 6 RED BLACK DC 0 5V Gas Valve CNG1 2 3 WHITE YELLOW DC 22 24V Confirm voltage as the M...

Page 52: ...ure Event Malfunctioning PCB Effects A component may not operate within the unit and could produce an error code In most cases of PCB failure the whole unit will not operate until the problem is resol...

Page 53: ...han 230 F or 110 C in heat exchanger will activate the high limit switch Failure Event Unable to detect excessively high water temperature if switch fails Effects Unable to shut down the boiler if the...

Page 54: ...279 Diagnostic 1 Visual inspection Check wire connections are secure 2 Check the resistance of the sensor Stop operating and lower the temperature before checking Testing inspection information Resist...

Page 55: ...an assembly screw is loose and or the fan is disassembled 3 Disconnected or defective fan connection terminal assembly Effects 1 Unstable combustion condition 2 Unit vibrating and noise 3 The boiler i...

Page 56: ...ing the ignition process 2 Produces multiple unsuccessful attempts to ignite Effects 1 The unit cannot ignite during the ignition process and E003 or E004 error codes will display 2 Durability of the...

Page 57: ...ssful attempts to ignite Effects 1 The unit cannot ignite during the ignition process and E003 or E004 error codes will display 2 Durability of the igniter wears down Error Code E003 E004 Diagnostic 1...

Page 58: ...e Effects 1 The boiler is not operating 2 Produces excessive carbon monoxide emissions Error Code E110 Diagnostic 1 Visual inspection Check wire connections are secure 2 Voltage check Check range of v...

Page 59: ...Event Unable to open close Effects 1 No flames 2 No operation of the unit Error Code E003 E012 Diagnostic 1 Visual inspection Check wire connections are secure 2 Check if the solenoid valve of Main G...

Page 60: ...1 Unable to initialize sustain combustion 2 Dust or soot deposit on the burner surface 3 Possible gas leakage from burners Effects 1 Abnormal combustion 2 Unstable flame conditions and or flame loss 3...

Page 61: ...at loss Failure Event 1 Water and or exhaust gas leakage through a crack 2 Improper heat transfer can cause the water in the heat exchanger to boil due to possible scale formation Effects 1 Exhaust ga...

Page 62: ...lure Event Unable to detect or measure changes in water pressure Effects 1 No operation of the unit 2 Pressure readings are abnormal Error Code E302 E352 E353 Diagnostic 1 Visual inspection Check the...

Page 63: ...ent 1 Blade not closing 2 Blade not opening 3 Gas plunger does not disengage Effects 1 Frequent On Off due to excessive heat 2 Fail to reach the set temperature due to lack of heat 3 Loss of flame dur...

Page 64: ...ure Event 1 Water leakage through a crack 2 Improper heat transfer can cause the heat exchanger to produce cold water Effects Temperature fluctuations in the hot water outlet and or leakage Error Code...

Page 65: ...c hot water in the DHW mode Effects In the case that the temperature of space heating is lower than the set temperature the water flow path for domestic hot water will start blocking so that heating w...

Page 66: ...valve E421 Abnormal Cold water intake sensor E434 Abnormal operation Water adjust valve E439 Abnormal operation flow sensor E441 Hot water outlet 2 before mixing valve E445 Abnormal operation Bypass m...

Page 67: ...al DIP switch setting Manual RESET E594 1 Abnormal communication in parts of PCB Alarm E615 3 Abnormal input memory Manual RESET Installation System E736 1 Abnormal cascade communication Alarm E740 1...

Page 68: ...me detection 1 Ensure ground wire is connected 2 Check the igniter for spark E012 0 Flame loss 1 Check the main gas line Is the valve open 2 Verify gas pressure is within operating range 3 Check gas m...

Page 69: ...bstructions 2 Abnormal Dual Venturi Limit Switch operation Close OFF 3 Abnormal Dual Venturi Limit Switch operation Open ON E407 Abnormal Hot water outlet 1 sensor After mixing valve 1 Check for disco...

Page 70: ...istor short Check the thermistor E291 0 Supply Return inversion limit Check if the supply water outlet piping of heating piping and return inlet piping are mutually changed E302 0 Low water pressure C...

Page 71: ...curve is enabled E777 0 Abnormal operation LWCO external device 1 Check the LWCO wiring connection 2 Ensure that the system water level is appropriate 3 Add make up water to the system if necessary 4...

Page 72: ...d and must be manually reset Check items 1 Check the circulation pump external operating status Run Pump Test Mode 2 Check if the strainer of the heating piping is clogged 3 Check if the main heat exc...

Page 73: ...ner is clogged Aluminium distributor oxidized steel etc The main heat exchanger is clogged Separate the inlet outlet pipe from the main heat exchanger and blow air through the heat exchanger to check...

Page 74: ...t circuit solenoid valve 5 Check the flame rod wiring and grounding 6 Check if the air pressure hose is broken or clogged 7 Check if the air pressure sensor works properly 8 Check the PCB DIP switch s...

Page 75: ...he RED WHITE 1 and 3 of CNG1 22 24 VDC Insufficient gas supply pressure can cause Ignition Failure Normal gas pressure LP 8 13 5 W C NG 3 5 10 5 W C Yes No No No Yes Yes Scenario3 Is the flame detecti...

Page 76: ...bustion 2nd stage MAX combustion setting DIP S W 1 1 ON 5 If a CSST connector has been used check to ensure that it is not been over tightened resulting in the seal obstructing gas flow 6 Check the me...

Page 77: ...if there is a discharge of electricity from the metallic part of the burner Ensure that the insulating gasket is installed between the electrode and burner casing Check the input power to the ignitio...

Page 78: ...he RED YELLOW and WHITE RED wires to verify that the input power is DC 22 24V 2 Replace the PCB if power is not supplied 3 If power supply is normal check if the coil is open Check the resistance 4 Ch...

Page 79: ...ve and reattach the ground wire ensuring good contact with the case Or use a multi meter to measure the flame sensing current normally over 3 4 A Measuring flame current Grounding wire position Flame...

Page 80: ...ange 4 Check the PCB and replace if defective Is the flame detected in the burner when there is no ignition External noise current Clean or replace flame rod Check the current 2 of CNI1 Over 3 4 A See...

Page 81: ...nsecutively displays 012E manually cleared on the front panel Check items 1 Measure with a manometer the gas supply pressure NG 3 5 10 5 W C LP 8 13 5 W C 2 Check the gas meter capacity 3 Check if the...

Page 82: ...obstructing gas flow 6 Check the gas meter capacity Example Gas meter Boiler Furnace Domestic gas stove 425 CFH Gas Meter 195 CFH Boiler 58 8 CFH Furnace 63 7 CFH Domestic gas stove CFH 1 020 BTU h 7...

Page 83: ...o the properties of the electrode the oxide film is created due to long term exposure to the high temperature therefore errors may be caused in detecting the fires Check up Use sandpaper to clean the...

Page 84: ...troller is working properly Check resistance value or continuity refer to page 53 2 Check the hot water temperature sensor refer to page 54 3 Check for proper power supply 120 VAC to the pump external...

Page 85: ...e sensor check if the deviation of temperature is large due to a defective temperature sensor Check the output temperature displayed on the front panel 2 Measure the temperature sensor resistance and...

Page 86: ...of 230 F 110 C for 10 minutes or over E030 error code will display and perform post purge Automatically cleared 2 When the controller detects the exceeding temperature of 140 F 60 C while performing...

Page 87: ...xchanger if it is damaged or cannot be unclogged Defective part Defective temperature sensor Defective contact point of the exhaust gas overheat controller 230 F 110 C Max Check connection of the over...

Page 88: ...r thermistor Check connector 13 and 14 of CNJ1 1 step Flushing Clean Filter 2 step Try to restart 3 step Replace PCB Yes Yes No No 5 2 8 047Error Error occurrence conditions and check items Is exhaust...

Page 89: ...Dual Venturi is operating correctly Run the Dual Venturi Test Mode 2 Check that the wiring harness is connected correctly and the cables are not damaged Is Dual venturi closed Is Dual venturi repeated...

Page 90: ...3 Wait until Fan Auto Adjusting is complete 4 Enter the Dual Venturi Test Mode and perform a test 1 Repeat the test at least twice Turning the unit ON and OFF once makes one test cycle ON OFF ON OFF i...

Page 91: ...sensor should be normal Check items 1 Check if the fan motor works normally using the component test mode refer to page 43 2 Check the power supply to the fan Black Red approx DC 127 184 V 3 If RPM i...

Page 92: ...operating and the power supply is normal Follow the instructions listed below and replace the fan 1 Unplug the power cable to the unit and then wait for 10 seconds until the remaining SMPS voltage com...

Page 93: ...ndensation drain line or the drain is clogged 2 Check the flue and exhaust to verify proper installation and clearances Circulation of exhaust gas generates noise 3 Check if the air supply exhaust flu...

Page 94: ...clogged 2 Replace the old PCB with the latest version Condensate drain error Condensate drain error Exhaust air is blocked due to condensate drain error Check if the condensate hose or the siphon is...

Page 95: ...age 2 Replace the defected heat exchanger output temperature sensor 3 Check circulation pump external type operating status and for proper flow through the space heating line 4 Check the voltage on th...

Page 96: ...ve if it is 30k or higher Replace the temperature sensor if the resistance value is abnormal refer to page 54 Check the temperature displayed on the front panel refer to page 36 Possible Issues Defect...

Page 97: ...nitiates shutdown Check items 1 Check if the heat exchanger input temperature sensor connector is wet due to any reason including leakage 2 Replace the defected heat exchanger input temperature sensor...

Page 98: ...resistance of the temperature sensor Defective if it is 30k or higher Replace the temperature sensor if the resistance value is abnormal refer to page 54 Check the temperature displayed on the front p...

Page 99: ...ply temperature sensor normal Check connector 7 and 8 of CNT1 Replace system supply thermistor Resistance between 7 and 8 of CNT1 is from 0 437k to 176k at normal condition See page 50 for Wiring Diag...

Page 100: ...m return temperature sensor normal Check connector 7 and 8 of CNT2 Replace system return thermistor Resistance between 7 and 8 of CNT2 is from 0 437k to 176k at normal condition See page 50 for Wiring...

Page 101: ...connection is inversed 2 Check the supply temperature sensor connection 3 Check the return temperature sensor connection Is the space heating pipe connection normal Check the supply and return temper...

Page 102: ...ater supplied pipe open 3 Check the water pressure sensor Leaking in unit Is the cold water valve open 1 Check cold water pressure 2 Check the water pressure sensor Check leaking in unit Open the cold...

Page 103: ...check with circuit tester whether there is a disconnection between harness sockets 4 Change auto feeder valve If the problem persists after completing 1 2 and 3 change the auto feeder valve 5 Check p...

Page 104: ...including leakage 2 Check the controller Is the cold water fill valve or the pressure safety valve malfunctioning Is the water pressure sensor normal 1 Check connecter 4 5 and 6 of CNG1 Replace the m...

Page 105: ...eck if the cold water pipe input water pressure sensor is wet due to any reason including leakage 2 Replace the water pressure sensor 3 Check the controller Leaking in unit Is the water pressure senso...

Page 106: ...ons between the hot water outlet 1 temperature sensor after mixing harness 2 Change hot water outlet 1 temperature sensor after mixing If the problem persists after completing 1 close the external dir...

Page 107: ...or disconnections between harness connecting controller and water intake temperature sensor 2 Change water intake temperature sensor If the problem persists after completing 1 close external water int...

Page 108: ...ss disconnection Check for harness disconnection in case no feedback signal 2 Change water adjust valve If the problem persists after completing 1 close external water intake supply valve and purge wa...

Page 109: ...ness disconnection Check for disconnections between harness connecting controller and water adjust valve 2 Change water flow sensor If the problem persists after completing change the water flow valve...

Page 110: ...ection in the harness between hot water outlet 2 temperature sensor and the controller 2 Change hot water outlet 2 temperature sensor If the problem persists after completing close external water supp...

Page 111: ...ness disconnections If there is no feedback signal check for disconnections that may cause this error 2 Change mixing valve If the problem persists after completing close external water supply valve a...

Page 112: ...page 59 Check the Fan voltage See page 50 51 forWiring Diagram 1 Check the wire connection between dual venturi and Main controller 2 Check the dual venturi 1 Turn off and on the Power RESET switch 2...

Page 113: ...onditions and check items Error Description E594 error If the communication is abnormal in parts of PCB the system displays E594 on the PCB Check items Check the PCB Error occurrence conditions and ch...

Page 114: ...Abnormal outdoor sensor If an error under 2 2k or over 122 2k in the outdoor sensor is detected continuously for 3 seconds The system displays the error message E740 on the front panel If this occurs...

Page 115: ...r power being supplied to the LWCO Replace the main PCB Check LWCO Check the factory installed jumper and jumper connection 1 and 2 of CNC3 Check the connecting terminals 1 and 2 of CNC3 No No Yes No...

Page 116: ...the PCB 1 step Reset the unit 2 step If problem persists replace the PCB and Front panel Yes NO 5 2 34 784Error Error occurrence conditions and check items Is the wiring from the boiler PCB properly...

Page 117: ...e the decompression transformer If the problem persists after completing 1 and 2 change the decompression transformer 4 Change the PCB If the problem persists after completing all the actions above ch...

Page 118: ...problem such as the burner s drooping tearing or scraping Change to a new one if the current burner has a problem Or move on to the next step below 2 Check if the temperature fuse harness is disconnec...

Page 119: ...below the standard 2 Gas supply error due to defective air pressure sensor 3 If the same error is repeated it is due to a defective PCB Noise during combustion Boiling noise How to check boiling Boil...

Page 120: ...panel Water mixed with cold water The temperature of hot water at the tap is low while the temperature is high at the hot water outlet Cold water and hot water are mixed due to improper pipe installa...

Page 121: ...8 10 inches long A flashlight and magnetic tip are also recommended Navien recommends the use of a parts tray to hold small parts and screws All of the hardware is essential to the proper operation of...

Page 122: ...t it is properly fixed inside the housing 6 Turn on water supply power supply and gas supply to the unit 6 2 3 Fan Combustion Air 1 Turn off the gas supply to the unit 2 Disconnect the unit from the p...

Page 123: ...5 Remove the 4 screws from the flame rod as shown in Figure below Figure 10 6 Remove the flame rod wiring connector 7 Remove the flame rod from the burner assembly and replace with the new part 8 Rec...

Page 124: ...d to the igniter probe connectors 6 2 6 APS 1 Turn off the gas supply to the unit 2 Disconnect the unit from the power supply 3 Turn off the water supply to the unit 4 Remove the air pressure sensor w...

Page 125: ...15 6 2 8 Water Pressure Sensor 1 Turn off the gas supply to the unit 2 Turn off the 120V power supply to the unit 3 Turn off the water supply to the unit Drain all water from the appliance 4 Disconne...

Page 126: ...126 NFC Service Manual Version 1 0 7 1 Case Assembly 11 6 14 5 12 1 13 10 9 3 1 8 15 7 4 2 3 2 7 Components Diagram and Part List...

Page 127: ...30019951A 4 Front Panel 30019664A 5 Exhaust Duct Assembly 30008673A 6 Intake Air Duct Assembly 30008662B 7 Intake Air Filter 20007667A 8 PCB Lower Bracket 20041079A 9 Rubber Ring 20029318A 10 24 V Po...

Page 128: ...128 NFC Service Manual Version 1 0 7 2 Heat Exchanger and Waterway Assembly 21 22 20 19 18 17 16 23 14 26 26 31 1 4 5 4 3 26 25 24 7 7 7 9 4 10 26 7 2 27 28 29 30 11 13 12 26 8 15 6 7 8 26...

Page 129: ...pter 30019648A 12 Return Pipe 30019175A 13 Thermistor 30012907A 14 Air Pressure Sensor 30015811A 15 Drain Pan Packing 20040241A 16 Exhaust Duct Lower 20040242A 17 Exhaust Duct Clip 20042741A 18 Exhaus...

Page 130: ...130 NFC Service Manual Version 1 0 7 3 Combustion Parts Assembly 2 28 27 9 31 10 11 1 3 4 13 31 31 31 32 33 5 6 7 9 9 12 9 8 26 25 20 21 22 23 29 15 14 24 30 34 37 16 17 34 36 19 18 35...

Page 131: ...Rod Packing 20040230A 18 Igniter 30019165A 19 Igniter Packing 20040229A 20 Flame Inspection Window Upper 20040231A 21 Flame Inspection Window Lower 20040232A 22 Flame Inspection Window Graphite Packin...

Page 132: ...e Return Filter YES NO Checking the Intake Air Filter YES NO Flushing the Heat Exchanger YES NO Replacement of Parts YES NO 8 3 Maintenance Schedules Owner maintenance Daily Check boiler area Check pr...

Page 133: ...Memo...

Page 134: ...Memo...

Page 135: ...Memo...

Page 136: ...Memo...

Page 137: ...Memo...

Page 138: ...r Contact a licensed professional for the affected system for example a plumber or electrician When you contact Technical Support please have the following information at hand Model number Serial numb...

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