Navien NFC-175 Service Manual
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Navien NFC-175 Service Manual

Nfc condensing boilers
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Service Manual
NFC Condensing Boilers
Model
NFC-175
NFC-200
WARNING
If the information in these instructions is not followed exactly, a fire or explosion may result, causing
property damage, personal injury, or death.
Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other
appliance.
WHAT TO DO IF YOU SMELL GAS
Do not try to light 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 cannot reach your gas supplier, call the fire department.
●
Installation and service must be performed by a qualified installer, service agency or the gas
supplier.
Keep this manual near this boiler for
future reference whenever maintenance
or service is required.

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Summary of Contents for Navien NFC-175

  • Page 1 Service Manual NFC Condensing Boilers Model NFC-175 NFC-200 Keep this manual near this boiler for future reference whenever maintenance or service is required. WARNING If the information in these instructions is not followed exactly, a fire or explosion may result, causing property damage, personal injury, or death.
  • Page 2 Revisions Version Description of changes Date First Issue December / 2018 Version 1.0 NFC Service Manual...

  • Page 3: Table Of Contents

    Contents 1. Safety Information 4.9 Accessing Advanced Menu Items 4.9.1 Viewing Service Information 1.1 Safety Definitions 4.9.2 Viewing Input and Output Status 1.2 Safety Symbols 4.9.3 Setting the Operation Parameters 1.3 Symbols Used in the Instructions 4.9.4 Configuring a Cascade System 1.4 Safety Precautions 4.9.5 Setting the External Connection (for NaviLink) 4.9.6 Diagnosing the Boiler System...
  • Page 4 7. Components Diagram and Part List 5.2.11 110Error 5.2.12 205Error 7.1 Case Assembly 5.2.13 218Error 7.2 Heat Exchanger and Waterway Assembly 5.2.14 278Error 7.3 Combustion Parts Assembly 5.2.15 279Error 5.2.16 291Error 8. Inspection and Maintenance Schedule 5.2.17 302Error 8.1 Annual Servicing 5.2.18 351Error 8.2 Maintenance Report 5.2.19 352Error...
  • Page 5 Requirements for the State of Massachusetts NOTICE BEFORE INSTALLATION This appliance must be installed by a licensed plumber or gas fitter in accordance with the Massachusetts Plumbing and Fuel Gas Code 248 CMR Sections 4.00 and 5.00. IMPORTANT: In the State of Massachusetts (248 CMR 4.00 & 5.00) For all side wall horizontally vented gas fueled equipment installed in every dwelling, building or structure used in whole or in part for residential purposes, including those owned or operated by the Commonwealth and where the side wall exhaust vent termination is less than seven (7) feet above finished grade in the area of the venting, including but not limited to decks and porches, the following requirements shall...
  • Page 6 Navien Warranty Warranty Period Navien will pay labor charges for the repair subject to Navien’s prior written approval and in accordance with Navien’s schedule Navien products come with a limited warranty covering labor, of approved labor allowances for a period of one (1) year from the parts and the heat exchanger.
  • Page 7 Product. NAVIEN SHALL NOT IN ANY Any damage, malfunction or failure caused by abuse, ●...
  • Page 8 Abbreviations and Definitions Abbreviation Definition General name of NFC-175, NFC-200 Natural Gas Propane Gas Air Pressure Air Pressure Sensor Domestic Hot Water Fan Motor Gallons Per Minute Main Gas Valve Revolutions Per Minute Printed Circuit Board Electromagnetic Interface High Temperature Limiter...

  • Page 9: Safety Information

    1. Safety Information 1.1 Safety Definitions 1.3 Symbols Used in the Instructions The following safety symbols are used in this manual. Read and follow all safety instructions in this manual precisely to avoid IMPORTANT unsafe operating conditions, fire, explosion, property damage, personal injury, or death.
  • Page 10 DANGER DANGER COMPROMISED VENTING SYSTEM Failure to follow the Venting Section of the installation ● manual may result in unsafe operation of this boiler. To avoid the risk of fire, 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.
  • Page 11 CAN-B149.1 and CAN1-B149.2 Installation Code. DO NOT attempt to change the water temperature while ● Navien Inc. is not liable for any property damage and/or someone is using the boiler. personal injury resulting from unauthorized conversions. DO NOT use parts other than those specified for this ●...
  • Page 12 CAUTION WARNING Do not attempt to repair or replace any part of the boiler, ● unless it is specifically recommended in this manual. For all other service, contact an authorized technician or licensed professional. Improper adjustments, alterations, service, or maintenance may lead to property damage, personal injury, or death and will void your warranty.

  • Page 13: Product Information

    2. Product Information 2.1 Product Information Items Navien features the NFC Series gas boiler. This appliance is fully modulating and provides central heating. Depending on the heat capacity, each model is divided into two types; 175 and 200. Model Maximum Space Heating Input...

  • Page 14: Components

    2.2 Components The following diagram shows the key components of the boiler. Component assembly diagrams and particular parts lists are included in the Appendixes. Intake Air Exhaust PRV-Air Vent Connection Mixing Chamber Fan & Motor Assembly Igniter Flame Rod Dual Venturi Igniter Transformer Fire-Tube Type Heat Exchanger...
  • Page 15 Intake Air Filter Mixing Chamber Fan & Motor Assembly Dual Venturi Igniter Flame Rod Igniter Transformer Gas Valve Fire-Tube Type Heat Exchanger Air Intake Pipe Gas Pipe ASME Name Plate Front Panel Terminal Block Circulation Pump Power Switch Mixing Valve Water Adjust Valve DHW Exchanger 3-Way Valve...

  • Page 16: Technical Data

    2. Based on U.S. Department of Energy (DOE) test procedures. 3. The net AHRI water ratings shown are based on a piping and pickup allowance of 1.15. Consult Navien before selecting a boiler for installations having unusual piping and pickup requirements, such as intermittent system operation, extensive piping system, etc.
  • Page 17 The NFC boiler is equipped with an internal circulation pump. The following table provides detailed information on the pump used for the boiler and the performance curve. Item Pump Model NFC-175/200 Grundfos UPS 15-78 CIL2 Internal Recirculation Pump (Part Number: 30021636A)
  • Page 18 General Specifications Item NFC-175 NFC-200 Dimensions 17.3 in (W) x 17.3 in (D) x 33.5 in (H) Boiler Weight 145 lb (66 kg) Boiler Weight with Water 183 lb (83 kg) Installation Type Indoor Wall-Hung Venting Type Forced Draft Direct Vent...

  • Page 19: Dimensions

    3.2 Dimensions The following diagrams show the dimensions of the boiler and the table lists the supply connections. Supply Connections Description Diameter Air Intake 2 in Exhaust Gas Vent 2 in Air Vent Connection Heating Supply 1 in Heating Return 1 in Gas Connection Condensate Outlet...

  • Page 20: System Details

    1-stage MIN 1-OFF, 2-ON Space Used 7-OFF 1-stage MAX 1-ON, 2-ON Heating Unused 7-ON 3 & 4 Reserved Thermostat NFC-200 5-OFF, 6-OFF Exhaust Used 8-OFF 5 & 6 Model Temperature NFC-175 5-ON, 6-OFF Unused 8-ON Control Version 1.0 NFC Service Manual...

  • Page 21: Measuring The Inlet Gas Pressure

    4.3 Measuring the Inlet Gas Pressure When PCB DIP switch 2 #8 is set to On, ensure that Note ● CPVC, polypropylene, or stainless steel is used for exhaust venting. This unit may be installed at elevations up to 10,100 WARNING ●...
  • Page 22 9. Loosen the screws indicated in the figure below and connect a 3. Press the Command dial ( ) to enter special operation mode. manometer to the pressure port. Reset the manometer to zero before use. ) to move to 7. SH 2nd MAX, 4.

  • Page 23: Gas Pipe Sizing Tables

    4.3.1 Gas Pipe Sizing Tables The following tables are referenced from the 2012 National Fuel Gas Code and are for reference only. Please consult the gas pipe manufacturer for actual pipe capacities. Maximum Natural Gas Delivery Capacity In Cubic Feet (ft ) per Hour (0.60 Specific Gravity;...
  • Page 24 Maximum Liquefied Propane Delivery Capacity In Thousands of BTU/H (0.5 in WC pressure drop) Length (including fittings) Pipe Size 10 ft 20 ft 30 ft 40 ft 50 ft 60 ft 80 ft 100 ft 125 ft 150 ft 175 ft 200 ft 250 ft (3 m)

  • Page 25: Gas & High Altitude Conversion

    WARNING This conversion kit must be installed by a qualified service WARNING agency* in accordance with Navien’s instructions and all applicable codes and requirements of the authority having jurisdiction. The information in these instructions must be Be careful not to confuse the LP CONVERSION KIT and HIGH ●...
  • Page 26 Procedure: 4. With the internal components exposed, locate the gas inlet pipe and the gas valve, as shown in Figure 2. The procedure below can be applied to both LP Note conversion and High Altitude conversion. Distinguish the kit supplied with the boiler before installing. 1.
  • Page 27 Attempting to alter or measure the gas valve outlet pressure ● could result in damage to the valve, causing potential severe personal injury, death or substantial property damage. Navien NFC boilers are shipped ready to fire natural gas ONLY. Figure 5. Exploded View of Gas Pipe Assembly Version 1.0...
  • Page 28 8. Remove the Gas Orifice, ensure that the packing is properly This unit may be installed at elevations up to 10,100 ft Note ● seated inside the port, and then install the new Gas Orifice for (3,078 m) for use with natural gas and propane. use with LP gas.
  • Page 29 1-stage MIN 1-OFF, 2-ON 1-stage MAX 1-ON, 2-ON Figure 6. Insert the Analyzer 3 & 4 Reserved NFC-200 5-OFF, 6-OFF 5 & 6 Model NFC-175 5-ON, 6-OFF High fire Low fire Model Altitude Fuel 0-5,399 ft 10.2 10.8 NFC-175 NFC-200 5,400-10,100 ft 10.2...
  • Page 30 Model Altitude Kit Part No. Gas Type Offset 0-5,399 ft NAC-N200 -0.04 in ±0.01 in NFC-175 5,400-10,100 ft NAC-NCH200 Figure 7. Set Screw Location NFC-200 -0.02 in 0-10,100 ft NAC-LC200 ±0.01 in The set screw is located behind the screw-on Note cover.
  • Page 31 c. Activate multiple zones and set the boiler to operate 13. Once the CO or offset values have been confirmed, apply the at 1-stage MIN mode (refer to “4.9.7 Setting the Special included conversion stickers to show that the appliance has Operation Modes”...

  • Page 32: The Front Panel

    4.5 The Front Panel The front panel allows you to adjust the temperature and view the operating status or error codes. Remove the protective sheet from the front panel before using it. 4.5.1 Icons and Digital Display The icons and digital display on the front panel provide important information required for the boiler’s operation.

  • Page 33: Buttons And Command Dial

    4.5.2 Buttons and Command dial Using the buttons and the Command dial on the front panel, you can turn on or off the boiler, monitor the current operation status, and set the values required for the boiler’s operation, such as space heating and DHW supply temperatures.

  • Page 34: Turning The Boiler On Or Off

    4.6 Turning the Boiler On or Off 2. Press the Command dial ( ) to select the space heating temperature. The highlighted section will flash. To turn the boiler on or off, press the Power button for 0.3 seconds. 3. Rotate the Command dial ( ) to the right or left to increase or decrease the temperature.

  • Page 35: Adjusting The Dhw Temperature

    4.7.2 Adjusting the DHW Temperature 6. Press the Back button ( ) to return to normal operation mode, or rotate the Command dial ( ) to adjust other To adjust the water temperature: operation conditions. You can adjust the temperature while the display is flashing. Once 1.

  • Page 36: Accessing Basic Menu Items

    4.8 Accessing Basic Menu Items 4.8.2 Viewing Basic Information To view information about the boiler, press the Menu button ( In the Main Menu screen, you can view the boiler’s operating and then select “2. Status Information”. conditions, configure the space heating and DHW temperatures, and review error history.

  • Page 37: Setting The Space Heating Operation

    4.8.3 Setting the Space Heating Operation Item Description Flame detector AD value To set the boiler’s space heating operation, press the Menu button ), and then select “3. Space Htg Operation”. Flame On: 8bit AD values equal to or ● 16.

  • Page 38: Setting The Dhw Operation

    In the Outdoor Reset Control mode, the boiler’s water Enable or disable heating zones utilizing Note temperature is regulated according to the outdoor the Navien Zone Controller. 3. Navien zone cont. temperature to maximize boiler efficiency and reduce Setting range: Enabled/Disabled ●...
  • Page 39 Press the Back button ( ) to return to the previous screen or menu. Combi Pre-Heat Item Description When using the combi pre-heat feature, you can choose commands in the menu to preheat according to the set DHW Set the hot water temperature(°F). temperature.
  • Page 40 External Recirculation When Installing the Cascade System When using the External Recirculation feature, you can choose When using the recirculation feature in the cascade system , you commands in the menu to preheat according to the set DHW can choose commands in the menu to preheat according to the temperature.

  • Page 41: Viewing Error History

    4.8.5 Viewing Error History 4.8.6 Viewing Other System Information To view the error history, press the Menu button ( ), and then To view the miscellaneous system information, press the Menu select “5. Error History”. button ( ), and then select “6. EMS Data”. A list of 10 recent errors are displayed on the screen, with the most Rotate the Command dial ( ) to switch between the information...

  • Page 42: Setting The Display Options

    4.8.7 Setting the Display Options 4.9 Accessing Advanced Menu Items To set the front panel display options, press the Menu button ( and then select “7. Configuration”. 4.9.1 Viewing Service Information To view service information about the boiler, press the Back button ) and the Menu button ( ) simultaneously for 3 seconds, and then select “1.Service Status Info”.

  • Page 43: Viewing Input And Output Status

    4.9.2 Viewing Input and Output Status Item Description To view the boiler’s input and output status, press the Back button 14. LWCO Input LWCO input status ) and the Menu button ( ) simultaneously for 3 seconds, and Status then select “2. Input/Output Status”. 15.
  • Page 44 Press the Back button ( ) to return to the previous screen or Item Description menu. Set the low-load combustion time at initial operation. 9. SH Min Burning Item Description Time Setting range: 1 – 20 min ● Set the space heating supply minimum Default: 1 min ●...
  • Page 45 If you enter an incorrect password 10 times or no Note ● Item Description input from the front panel display for 5 minutes, the Set the DHW wait time. boiler will return to Normal mode. 18. DHW Wait Time To return to the previous mode, press the Reset Setting range: 0 –...

  • Page 46: Configuring A Cascade System

    4.9.4 Configuring a Cascade System Item Description To view and configure the cascade settings, press the Back button Select this option on the Main unit ) and the Menu button ( ) simultaneously for 3 seconds, of a cascade system to end cascade and then select “4.

  • Page 47: Setting The External Connection (For Navilink)

    4.9.5 Setting the External Connection (for 4.9.6 Diagnosing the Boiler System NaviLink) To run a series of test procedures for a system diagnosis, press the Back button ( ) and the Menu button ( ) simultaneously for 3 To view and configure the external network connection, press the seconds, and then select “6.

  • Page 48: Setting The Special Operation Modes

    4.9.7 Setting the Special Operation Modes Item Description Test the zone 2 pump operation. To operate the boiler in special operation modes, press the Back button ( ) and the Menu button ( ) simultaneously for The zone 2 pump is turned on as ●...

  • Page 49: Ladder Diagram

    4.10 Ladder Diagram AC INPUT(AC 120VAC) NEUTRAL Terminal Board Relay 1 R/C Pump Relay 2 Boiler Pump Relay 3 Zone1 Pump Relay 4 Zone2 Pump Relay 5 Zone3 Pump FILTER Dual Venturi Relay 5 Relay 6 Igniter 3WAY VALVE Relay 7 Primary Primary SMPS...

  • Page 50: Wiring Diagram

    4.11 Wiring Diagram Main GV1 Main GV2 THERMOSTAT3 T/S1 Outdoor Temperature Sensor Flow Sensor OUTDOOR System Return Temperature Sensor RETURN AWS_Valve System Supply Temperature Sensor SUPPLY Version 1.0 NFC Service Manual...
  • Page 51 Point Function CN No. Wire Color Normal Value Check Voltage changes according to Exhaust Thermistor CNJ1 1-2 BLUE-BLUE DC 0-5V temperature Heating Return Voltage changes according to CNJ1 5-6 BLUE-BLUE DC 0-5V Temperature Sensor temperature Heating Supply Voltage changes according to CNJ1 7-8 BLUE-BLUE DC 0-5V...

  • Page 52: Key Components Description

    4.12 Key Components Description 4.12.1 PCB Part Check Point Function Controls each component and monitors the overall performance of the unit. Failure Event Malfunctioning PCB. A component may not operate within the unit and could produce an error code. In most cases of Effects PCB failure, the whole unit will not operate until the problem is resolved.

  • Page 53: High Limit Switch

    4.12.2 High Limit Switch Part Check Point 1. Overheat prevention switch. 2. If the unit detects extremely high temperatures, it will automatically trip and shut down the Function unit. 3. Excessively high water temperatures (more than 230 °F or 110 °C) in heat exchanger will activate the high limit switch.

  • Page 54: Thermistor

    4.12.3 Thermistor Part Check Point Function Measure Hot water, Cold water, Space heating outlet and inlet temperatures in the boiler. Failure Event Unable to properly measure water temperature within the boiler. 1. If any of the thermistors fail, an error code appears before starting operation. Effects 2.

  • Page 55: Fan Motor

    4.12.4 Fan Motor Part Check Point Provides combustion air into the burner and purges exhaust flue gas. Function Maintains the gas input with a long vent run, the fan operates with APS for ideal combustion. 1. Fan speed failure: the fan RPM is around 0 RPM. Failure Event 2.

  • Page 56: Flame Rod Assembly

    4.12.5 Flame Rod Assembly Part Check Point Function Continuously discharges a high voltage spark to the main burner until gas ignites. 1. Unable to ignite during the ignition process. Failure Event 2. Produces multiple unsuccessful attempts to ignite. 1. The unit cannot ignite during the ignition process and “E003” or “E004” error codes will display. Effects 2.

  • Page 57: Ignition Transformer

    4.12.6 Ignition Transformer Part Check Point Function Continuously provides a high voltage to flame rod until gas ignites. 1. Unable to ignite during the ignition process. Failure Event 2. Produces multiple unsuccessful attempts to ignite. 1. The unit cannot ignite during the ignition process and “E003” or “E004” error codes will display. Effects 2.

  • Page 58: Aps

    4.12.7 APS Part Check Point Function Detects the air pressure in the combustion system. 1. Combustion noise occurs. Failure Event 2. Imperfect and/or abnormal flame occurs. 3. Occurs when APS does not detect proper voltage. 1. The boiler is not operating. Effects 2.

  • Page 59: Main Gas Valve

    4.12.8 Main Gas Valve Part Check Point 1. To control the amount of gas supplied to the burner based on fan speed. Function 2. When the unit experiences abnormal combustion, it shuts off the gas valve automatically and prevents unsafe situations. Failure Event Unable to open/close 1.

  • Page 60: Burner

    4.12.9 Burner Part Check Point 1. Pre-Mix system reduces emissions and increase efficiency. Function 2. The burner facilitates the air/gas mixture necessary to produce the proper heat during combustion. 1. Unable to initialize/sustain combustion. Failure Event 2. Dust or soot deposit on the burner surface 3.

  • Page 61: Heat Exchanger Assembly

    4.12.10 Heat Exchanger Assembly Part Check Point 1. Main part for heat transfer from the burner. Function 2. There are multiple paths of water pipes on the heat exchanger surface as well as inside the combustion chamber which minimizes the heat loss. 1.

  • Page 62: Water Pressure Sensor

    4.12.11 Water Pressure Sensor Part Check Point Function Detects water pressure in the heating system. Failure Event Unable to detect or measure changes in water pressure. 1. No operation of the unit. Effects 2. Pressure readings are abnormal. Error Code E302, E352, E353 1.

  • Page 63: Dual Venturi

    4.12.12 Dual Venturi Part Check Point Controls the amount of mixed gas to modulate heating input. Function It uses synchronous motor to control the amount of mixed gas by stage 1 and 2. 1. Blade not closing Failure Event 2. Blade not opening 3.

  • Page 64: Dhw Heat Exchanger

    4.12.13 DHW Heat Exchanger Part Check Point Water heated in the primary/secondary heat exchanger is circulated to the plate heat exchanger, Function where the heat of hot water and tap water are exchanged so that hot water is available. 1. Water leakage through a crack. Failure Event 2.

  • Page 65: 3-Way Valve

    4.12.14 3-Way Valve Part Check Point Divert the water from the space heating system to the DHW plate heat exchanger and back based Function on input from DHW flow sensor and PCB. 1. No hot water in the space heating mode. Failure Event 2.

  • Page 66: Troubleshooting

    5. Troubleshooting 5.1 Error code classification Classification Error Code Error Level Function Self-diagnostic / Action Manual RESET E001 Overheating of heat exchanger Auto RESET E003 Ignition failure Manual RESET E004 False flame detection Auto RESET E012 Flame loss Manual RESET E016 Overheating of heat exchanger Manual RESET...
  • Page 67 Classification Error Code Error Level Function Self-diagnostic / Action E515 Abnormal PCB Manual RESET E517 Abnormal DIP switch setting Manual RESET Controller E594 Abnormal communication in parts of PCB Alarm E615 Abnormal input & memory Manual RESET E736 Abnormal cascade communication Alarm E740 Abnormal outdoor sensor...

  • Page 68: Error Code Classification

    5.2 Error code classification Error Code Sub Code Function / Cause Self-diagnostic / Action 1. Clean the strainer. 2. Check the pump for proper voltage from PCB(120VAC). E001 Overheating of Heat exchanger 3. Check for proper flow rate and circulation(external) through the heating line. 4.
  • Page 69 Error Code Sub Code Function / Cause Self-diagnostic / Action 1. Turn OFF the system for at least 30 minutes then restart. 2. Ensure all valves and filters on the boiler loop are Exhaust Overheat : exhaust limit switch open and clean. shuts down the unit when the flue E030 3.
  • Page 70 Error Code Sub Code Function / Cause Self-diagnostic / Action Exhaust blockage (checking the FAN) 1. Check the exhaust pipe for obstructions. 2. Check and clean the intake air filter. Exhaust blockage (Using hot water) 3. Remove exhaust pipe if possible to verify vent E110 blockage.
  • Page 71 3. Check the Main and Panel PCB. If any of the above solutions do not resolve the problem with the Boiler, contact Navien’s Technical department at 1-800-519-8794. There will be error codes displayed on the front panel and recorded on the PCB board (within the unit) of any problems or failures that occur with the Boiler.

  • Page 72: 001Error

    5.2.1 001Error Error occurrence conditions and check items Error Description 1. In order to prevent boiling in the heat exchanger, if the space heating water temperature is higher than 216°F(102°C), E001 will be displayed on the front panel. E001 2. If the space heating water temperature decreases below than 216°F(102°C), E001 will be Overheating of Heat automatically reset and the unit will repeat the combustion cycle.
  • Page 73 Sudden increase of temperature due to PCB DIP S / W model setting error or max setting. DIP S / W No. Capacity Capacity setting Other potential issues 175,000 BTU (NFC-175) 199,000 BTU (NFC-200) Defective PCB If the trouble continues despite the checking of above items, replace the PCB. Version 1.0 NFC Service Manual...

  • Page 74: 003Error

    5.2.2 003Error Error occurrence conditions and check items Error Description E003 In the case of an ignition failure, the boiler will attempt ignition 10 times. If no flame is Ignition failure detected, the system displays the error message 003E (manually cleared) on the Front Panel. 1.
  • Page 75 Scenario2 Is gas valve operating Does the main gas valve Check connector normally? have proper voltage? Check the voltage between the RED-YELLOW (#1 and #2) of CNG1: 22-24 VDC Check the voltage between the RED-WHITE (#1 and #3) of CNG1: 22-24 VDC Check that gas valve is open and Is gas valve open? check gas supply pressure...
  • Page 76 Check method Failure mode Cause Check method 1. Check if the main gas valve is open. 2. Check the gas supply pressure. NG: 3.5” - 10.5” W.C, LP: 8” – 13.5” W.C ● LP pressure drop occurs frequently in the winter. ●...
  • Page 77 Failure mode Cause Check method Igniter Flame Rod Ignite gap distance : 3.5~4.5mm (1/8”) When no spark is made from the electrode at ignition: Remove the electrode and check if there is a crack on the insulator. ● Adjust the gap if there is a discharge of electricity from the metallic part of the burner. ●...
  • Page 78 Failure mode Cause Check method 1. Check the primary/secondary power supply to the main gas valve. Check, with a multi-meter, between the 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. Main gas valve 3.
  • Page 79 Failure mode Cause Check method 1. Check the location of the flame, if there is any deformation or foreign substance, repair or replace the part. 2. Check the flame rod wire for proper connection and/or damage. Flame sensing error 3. Check the grounding to the boiler case to verify proper grounding at the outlet. If the ground wire is improperly connected or not making a good connection, ●...

  • Page 80: 004Error

    5.2.3 004Error Error occurrence conditions and check items Error Description 1. Pre ignition false-flame If a flame signal is detected continuously for 3 seconds before combustion (stand-by, pre- purge, pre-ignition), a false-flame error 004E (automatically cleared) is displayed on the front panel and the system performs continuous post-purge and operates the pump.

  • Page 81: 012Error

    5.2.4 012Error Error occurrence conditions and check items Error Description If the system detects loss of flame during combustion, the system stops supplying fuel, E012 attempts to restart, counts the incidents of flame loss, and if the incident occurs 20 times Flame loss consecutively displays 012E (manually cleared) on the front panel.
  • Page 82 Check method Fault Possible Causes Check method 1. Check if a gas valve is opened or not. 2. Check the gas supply pressure. NG: 3.5” - 10.5” W.C, LP: 8” - 13.5” W.C ● LP pressure drop occurs frequently in the winter. ●...
  • Page 83 Kit Part No. Offset Type 0-5,399 ft NAC-N200 Digital pressure -0.04 in manometer 5,400- ±0.01 in NFC-175 NAC-NCH200 10,100 ft NFC-200 -0.02 in 0-10,100 ft NAC-LC200 ±0.01 in Check the offset values for Min fire Offset value for low fire High fire...

  • Page 84: 016Error

    5.2.5 016Error Error occurrence conditions and check items Error Description If the overheat controller on the heat exchanger is initiated during combustion/standby of the E016 boiler, the system displays the 016E (manually cleared) message on the front panel. The boiler Bimetal overheated switches into Lock-Out, and performs post-purge continuously and operates the pump.
  • Page 85 Check method Fault Possible Causes Check method Check if the contact point of the overheat controller is defective. Defective overheat controller Use a multi-meter to see if the resistance is normal (0.3Ω) or abnormal (∞). ● Overheat controller Defective safety device Check if the overheat controller wire is disconnected ( Normal resistance : 0.3Ω...

  • Page 86: 030Error

    5.2.6 030Error Error occurrence conditions and check items Error Description If the temperature sensor on the bottom right of the exhaust duct is initiated, the system displays the exhaust overheat message 030E (cleared manually) on the front panel. The boiler switches into Lock-Out, and performs post-purge continuously and operates the pump.
  • Page 87 Check method Fault Possible Causes Check method 1. The error occurs due to high exhaust gas temperature caused by a damaged or clogged heat exchanger. Heat exchanger Damaged or clogged overheated heat exchanger 2. Flush the heat exchanger to remove scale deposits. 3.

  • Page 88: 046Error

    5.2.7 046Error Error occurrence conditions and check items Check connector Is high limit switch normally (#13 and #14 of CNJ1) operating? Is resistance within 1 step: Flushing, Clean Filter normal range? 2 step: Try to restart (refer to page 53) 3 step: Replace PCB Replace heat exchanger thermistor.

  • Page 89: 060Error

    5.2.9 060Error Error occurrence conditions and check items Error Description This error message is displayed on the front panel if the wiring is disconnected or the Dual E060 Venturi malfunctions. Dual Venturi error The boiler switches into Lock-Out, and performs post-purge continuously and operates the pump.
  • Page 90 Check method Fault Possible Causes Check method 1. Disconnect all cables from the Dual Venturi. Defective Dual Venturi cable or harness 2. Using a multi-meter, test the Dual Venturi electrical wiring. 1. Turn off the power to the unit using the main power switch (do not use the front panel power button) and wait for 10 seconds.

  • Page 91: 109Error

    5.2.10 109Error Error occurrence conditions and check items Error Description The system checks the RPM signal after the fan starts to run, and displays the error message 109E (cleared manually) in the following cases: 1. If the RPM remains low or close to 0, the system determines RPM error, and the boiler E109 switches into Lock-Out (gas valve and ignition transformer locked).
  • Page 92 Check method Fault Possible Causes Check method 1. Check the power supply to the blower. Black + Red, approx. DC 127~184 V ● 2. Replace the PCB if voltages are abnormal. (When replacing the PCB, turn off No fan operation the unit and then wait for at least 10 seconds before proceeding.) 3.

  • Page 93: 110Error

    5.2.11 110Error Error occurrence conditions and check items Error Description The system senses the air volume and the RPM signal, and displays 110E on the front panel in the following cases: E110 1. When the initial fan auto-adjust is not performed. Air pressure error 2.
  • Page 94 Check method Fault Possible Causes Check method 1. If 110E occurs intermittently during ignition or combustion, compare the standard RPM with the current RPM at Min / Max combustion (DIP switch 1-1&1-2). If the current RPM is higher than normal, check the following: 110E Abnormal flow of intake Air supply / exhaust vent for any blockages.

  • Page 95: 205Error

    5.2.12 205Error Error conditions and Check Items Error Description E205 If an error (open: 14°F (-10°C) or lower) in the heat exchanger input temperature sensor is Heat exchanger output temperature detected, the system displays the 205E error on the front panel. If this occurs, the boiler initiates sensor open shutdown.
  • Page 96 Check method Fault Possible Causes Check method Defective temperature Check if the temperature sensor is open and if the connector is connected sensor connector properly. Check the resistance of the temperature sensor. (Defective if it is 30kΩ or higher) Defective sensor Replace the temperature sensor if the resistance value is abnormal.

  • Page 97: 218Error

    5.2.13 218Error Error conditions and Check Items Error Description E218 If an error (open: MΩ) in the heat exchanger input temperature sensor is detected, the system Heat exchanger input temperature displays the 218E error on the front panel. If this occurs, the boiler initiates shutdown. sensor open 1.
  • Page 98 Check method Fault Possible Causes Check method Defective temperature Check if the temperature sensor is open and if the connector is connected sensor connector properly. Check the resistance of the temperature sensor. (Defective if it is 30kΩ or higher) Defective sensor Replace the temperature sensor if the resistance value is abnormal ●...

  • Page 99: 278Error

    5.2.14 278Error Error conditions and Check Items Error Description E278 If an error (open: MΩ) in the system supply temperature sensor is detected, the system displays System supply temperature sensor open the 278E error on the front panel. If this occurs, the boiler initiates shutdown. 1.

  • Page 100: 279Error

    5.2.15 279Error Error conditions and Check Items Error Description E279 If an error (open: MΩ) in the system return temperature sensor is detected, the system displays System return temperature sensor open the 279E error on the front panel. If this occurs, the boiler initiates shutdown. 1.

  • Page 101: 291Error

    5.2.16 291Error Error conditions and Check Items Error Description E291 If the return temperature is higher than “supply temperature + 10°F (5.5°C)”, the system stops Supply / Return inversion limit operation and displays error code (E291) on the front panel. 1.

  • Page 102: 302Error

    5.2.17 302Error Error conditions and Check Items Error Description If the automatic water pressure sensor detects that the water pressure is lower than [the standard water pressure] for more than three seconds consecutively, the system determines that there is no water in the boiler and piping and an error message of low water pressure (“302, ”...

  • Page 103: 351Error

    5.2.18 351Error Error Condition and Check Items Error Description E351 Abnormal Auto feeder valve 1. Check for leaks within the boiler interior. Leaks disrupt from securing target pressure. ● 2. Check pressure in direct water supply valve connection. Errors occur if water does not enter during the water supply function. Check if exterior ●...

  • Page 104: 352Error

    5.2.19 352Error Error conditions and Check Items Error Description If the automatic water pressure sensor detects that the water pressure is higher than [the standard water pressure] for more than three seconds consecutively, the system stops operation of the boiler and a high water pressure error message (“352, ” automatically cleared) is displayed.

  • Page 105: 353Error

    5.2.20 353Error Error conditions and Check Items Error Description If an error (under 0.3V or over 2.8V) in the water pressure sensor is detected continuously for E353 3 seconds, The system displays the error message E353 on the front panel. If this occurs, the Abnormal water pressure sensor boiler initiates shutdown.

  • Page 106: 407Error

    5.2.21 407Error Error Condition and Check Items Error Description E407 Abnormal Hot water outlet 1 sensor (After mixing valve) 1. Check for controller harness disconnection. Check for any disconnections between the hot water outlet 1 temperature sensor (after ● mixing) harness. 2.

  • Page 107: 421Error

    5.2.22 421Error Error Condition and Check Items Error Description E421 Abnormal Cold water intake sensor 1. Check for disconnection in controller harness. Check for disconnections between harness connecting controller and water intake ● temperature sensor. 2. Change water intake temperature sensor. Check Items If the problem persists after completing (1), close external water intake supply valve and ●...

  • Page 108: 434Error

    5.2.23 434Error Error Condition and Check Items Error Description E434 Abnormal operation: Water adjust valve 1. Check for water adjust valve harness disconnection. Check for harness disconnection in case no feedback signal. ● 2. Change water adjust valve Check Items If the problem persists after completing (1), close external water intake supply valve and ●...

  • Page 109: 439Error

    5.2.24 439Error Error Condition and Check Items Error Description E439 Abnormal operation: flow sensor 1. Check for water adjust valve harness disconnection. Check for disconnections between harness connecting controller and water adjust valve. ● 2. Change water flow sensor. Check Items If the problem persists after completing change the water flow valve.

  • Page 110: 441Error

    5.2.25 441Error Error Condition and Check Items Error Description E441 Hot water outlet 2 (before mixing valve) 1. Check for disconnections in controller harness Check for disconnection in the harness between hot water outlet 2 temperature sensor ● and the controller. 2.

  • Page 111: 445Error

    5.2.26 445Error Error Condition and Check Items Error Description E445 Abnormal operation: Bypass mixing valve 1. Check for mixing valve harness disconnections If there is no feedback signal check for disconnections that may cause this error. ● 2. Change mixing valve Check Items If the problem persists after completing, close external water supply valve and purge ●...

  • Page 112: 515Error

    5.2.27 515Error Error occurrence conditions and check items Error Description If an error occurs in the internal circuit of the PCB (e.g., resistance, transistor or relay fault), the E515 error system displays 515E (cleared manually) on the PCB. 1. Defective PCB. 2.

  • Page 113: 517Error

    5.2.28 517Error Error occurrence conditions and check items Are the DIP S / W on the PCB Reset the unit properly set? Change the DIP S / W to the * If problem persists, replace the PCB proper settings 5.2.29 594Error Error occurrence conditions and check items Error Description...

  • Page 114: 615Error

    5.2.30 615Error Error occurrence conditions and check items Error Description E615 error Abnormal signal input by PCB. 1. Turn the POWER RESET switch OFF then ON (or unplug and replug the power supply. Check items 2. If the system still displays E615, replace the main PCB. 5.2.31 740Error Error conditions and Check Items Error...

  • Page 115: 777Error

    5.2.32 777Error Error conditions and Check Items Check the factory installed jumper Is the factory jumper Is the LWCO installed installed properly on and jumper properly? #1 and #2 of CNC3? connection (#1 and #2 of CNC3) Check the connecting Is the output voltage Is proper power being terminals...

  • Page 116: 782Error

    5.2.33 782Error Error occurrence conditions and check items 1. step: Reset the unit. Is the wiring from the front panel 2. step: If problem persists, properly connected to the PCB? replace the PCB and Front panel. Reconnect panel to the PCB 5.2.34 784Error Error occurrence conditions and check items 1.

  • Page 117: 031Error

    5.2.35 777 & 031Error Error code Cause Check method 1. If a LWCO sensor is not equipped, (1) Check the controller connection terminal. When a LWCO sensor is not equipped, there is a terminal connecting the two holes in the controller. An error can occur if the terminal is not connected completely. (2) Check the decompression transformer harness.
  • Page 118 Error code Cause Check method 1. Check damage to the burner. An error occurs due to overheating of the burner. Separate the mixing chamber, check the burner, and, if necessary, change it to a new one. Detail observation is needed to discover a problem such as the burner’s drooping, tearing, or scraping.

  • Page 119: Troubleshooting Guide By Symptom

    5.3 Troubleshooting guide by symptom 5.3.1 Noise Error type Cause Check method Incorrect mounting to the wall or in an improper location. Defective installation Check for improper installation and reinstall the unit if necessary. ● Vibration caused due to defective blower. Vibration noise Check the blower.

  • Page 120: Water Temperature Issue

    5.3.2 Water Temperature Issue Error type Cause Check method Front panel power off Hot water does not run if the front panel is switched off. The temperature is sensed higher than the actual temperature due to a defective Boiler is not operating hot water (cold water) sensor.

  • Page 121: Replacement Of Parts

    To remove and replace any parts from the boiler, you will need a screwdriver that is at least 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 the unit upon re-assembly.

  • Page 122: Fuse

    6.2.2 Fuse 5. Disconnect wiring connectors of Fan and Venturi. 1. Turn off the gas supply to the unit. 2. Disconnect the unit from the power supply. 3. Locate damaged fuse housings in Figure 3 below. Figure 5 6. Remove the 4 fan screws from the Mixing Chamber. Figure 3 4.

  • Page 123: Flame Rod

    6.2.4 Flame Rod 8. Remove the 6 screws from Intake Pipe and Venturi. 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 Ignition Transformer insulated cables. 5.

  • Page 124: Aps

    6.2.6 APS 5. Disconnect the wiring connector from the Ignition Transformer. 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 wiring connector (Figure 13). Figure 11 6.

  • Page 125: Main Gas Valve

    6.2.7 Main Gas Valve 6.2.8 Water Pressure Sensor 1. Turn off the gas supply to the unit. 1. Turn off the gas supply to the unit. 2. Disconnect the unit from the power supply. 2. Turn off the 120V power supply to the unit. 3.

  • Page 126: Components Diagram And Part List

    7. Components Diagram and Part List 7.1 Case Assembly 3 -2 3 -1 Version 1.0 NFC Service Manual...
  • Page 127 Description Part # Remark Case Upper 20041092A Case Middle 20041094A Case Lower 20041096A Cover 30019181A Main PCB 30019689A Terminal PCB 30019951A Front Panel 30019664A Exhaust Duct Assembly 30008673A Intake Air Duct Assembly 30008662B Intake Air Filter 20007667A PCB Lower Bracket 20041079A Rubber Ring 20029318A...

  • Page 128: Heat Exchanger And Waterway Assembly

    7.2 Heat Exchanger and Waterway Assembly Version 1.0 NFC Service Manual...
  • Page 129 Description Part # Remark 30019155A NFC-200 Heat Exchanger Assembly 30019724A NFC-175 Drain Pan Assembly 30019173A Supply Pipe (Upper) 30019177A Packing (P27) 20041401A Heat Exchanger Outlet Adapter 30019645A Supply Pipe (Lower) 30019176A Fastener 20040255A Heating Supply Adapter 20040244A LWCO (Pressure Sensor)

  • Page 130: Combustion Parts Assembly

    7.3 Combustion Parts Assembly Version 1.0 NFC Service Manual...
  • Page 131 NFC-175 Venturi Packing 20018079A Dual Venturi 30017402A Intake Pipe 30019120A Orifice Packing 20022660A 20041039A NFC-200 (NG) 20041037A NFC-175 (NG) Gas Orifice 20041040A NFC-200 (LP) 20041038A NFC-175 (LP) O-ring (P34) 20019090A Gas Connector (Upper) 20042238A O-ring (P20) 20006934A Gas Connector Adapter...

  • Page 132: Inspection And Maintenance Schedule

    8. Inspection and Maintenance Schedule 8.1 Annual Servicing 8.3 Maintenance Schedules In order to maintain its safe and efficient operation, it is Owner maintenance recommended that the boiler is serviced annually. Check boiler area ● Daily Check pressure / temperature gauge ●...
  • Page 133 Memo...
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  • Page 137 Memo...
  • Page 138 Service Manual NFC Condensing Boilers Getting Service If your boiler requires service, you have several options for getting service: Contact Technical Support at 1-800-519-8794 or on the website: www.navien.com. ● For warranty service, always contact Technical Support first. ● Contact the technician or professional who installed your boiler.

This manual is also suitable for:

Nfc-200

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