Page 1: Condensing Boiler
● Serial number ● Date purchased ● Installation location and type ● Error code, if any appears on the front panel display. ● Version: 1.0(October. 27. 2013) Navien America, Inc. 20 Goodyear lrvine, CA 92618 TEL +949-420-0420 FAX +949-420-0430 www.navienamerica.com...
Page 2 Condensing Boiler Service Manual Model NCB-180/ 210/ 240 Keep this manual near this boiler for future reference whenever maintenance or service is required. * The wetted surface of this product contacted by consumable water contains less than one quarter of one percent(0.25%) of lead by weight.
Page 4 Revisions Version Description of changes Date 1.00 First Issue October/27/2013 1.00 Reviewed BY:...
Page 5: Table Of Contents
Contents 4.9.3 Thermistor 4.9.4 Fan Motor 1. Safety Information 4.9.5 Flame Rod Assembly 1.1 Safety Definitions 4.9.6 Ignition Transformer 4.9.7 APS 1.2 Safety Symbols 4.9.8 Main Gas Valve 1.3 Symbols Used in the Instructions 4.9.9 Burner 1.4 Safety Precautions 4.9.10 Flow Sensor 4.9.11 Primary Heat Exchanger 4.9.12 Secondary Heat Exchanger 2.
Page 6 6. Replacement of Parts 6.1 Replacement Procedure 6.2 Components Replacement Instructions 6.2.1 PCB 6.2.2 Fuse 6.2.3 Fan Motor (Combustion Air) 6.2.4 Flame Rod 6.2.5 Ignition Transformer 6.2.6 APS 6.2.7 Main Gas Valve 6.2.8 Condensate Trap 6.2.9 Flow Sensor 6.2.10 Circulation Pump 6.2.11 3-way Valve 6.2.12 Water Pressure Sensor 6.2.13 Space Heating Strainer...
Page 7 Requirements for the State of Massachusetts 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 2.00 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...
Page 8: Navien Warranty
Navien Warranty Warranty Exclusions Warranty Period Navien’s Limited Warranty shall be void in the event of an Navien products come with a limited warranty covering labor, occurrence of any of the following: parts and the heat exchanger. The following warranty periods ...
Page 9  Operating the boiler at water temperatures outside the factory calibrated temperature limits and/or exceeding the maximum setting of the high limit control.  Operating the boiler when it is not supplied with potable water at all times.  Subjecting the heat exchanger to pressures or firing rates greater or lesser than those shown on the rating plate.
Page 10 Abbreviations and Definitions Abbreviation Definition General name of NCB-180, NCB-210, and NCB-240 Natural Gas Propane Gas Air Pressure Air Pressure Sensor Domestic Hot Water Fan Motor GARC Gas Air Ratio Control Gallons Per Minute Main Gas Valve Revolutions Per Minute...
Page 11: Safety Information
1. Safety Information 1.1 Safety Definitions 1.4 Safety Precautions The following safety symbols are used in this manual. Read and DANGER follow all safety instructions in this manual precisely to avoid unsafe operating conditions, fire, explosion, property damage, personal injury, or death. FLAMMABLE MATERIALS Keep the area around the boiler clear and free from 1.2 Safety Symbols...
Page 12 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 13 Installation Code. the hot water after servicing.  DO NOT attempt to change the water temperature Navien America Inc. is not liable for any property while someone is using the boiler. damage and/or personal injury resulting from  DO NOT use parts other than those specified for this unauthorized conversions.
Page 14 WARNING CAUTION  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 15: Product Information
Space Heating appliance. Input INPUT  Do not use this appliance if any part has been under water. NCB-180 80,000 Btu/h 150,000 Btu/h Immediately call a qualified service technician to inspect the appliance and to replace any part of the NCB-210...
Page 17: 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 Air Filter Flue Duct Mixing Chamber Ignitor & Flame Rod Condensate Trap Front Panel Auto Feeder (Make-up water) Power Switch...
Page 18 Fan & Motor Dual Venturi Ignition Transformer High Limit Switch Premix Burner Primary Heat Exchanger Air Pipe Secondary Heat Exchanger Gas Pipe Pressure Sensor (LWCO) Air Vent DHW Heat Exchanger Gas Valve Circulation Pump Flow Sensor 3-Way Valve DHW Inlet Filter (with built-in flow restrictor) Space Heating Supply DHW Inlet...
Page 19: Technical Data
Heating Input, MBH Model Net AHRI Rating Water Heating Capacity , MBH AFUE Number NCB-180 93.5 NCB-210 93.6 NCB-240 93.3 1. Ratings are the same for natural gas models converted to propane use. 2. Heating capacity values are based on U.S. Department of Energy (DOE) test procedures.
Page 20 General Specifications Item NCB-180 NCB-210 NCB-240 Dimensions 17 in (W) x 28 in (H) x 12 in (D) Weight 74 lbs (34 kg) 84 lbs (38 kg) 84 lbs (38 kg) Installation Type Indoor Wall-Hung Venting Type Forced Draft Direct Vent...
Page 21: 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 Space Heating Supply 1 in Space Heating Return 1 in Hot Water Outlet (DHW) 3/4 in Gas Supply Inlet...
Page 22: System Details
DIP switches that control the functionality of the boiler. Set the DIP switches appropriately, based on the installation Reserved environment and the gas type. Reserved 4.1.1 Setting the DIP Switches 4-OFF, 5- NCB-180 Circuit Board DIP Switches 4-ON, 5- NCB-210 Capacity 5 & 6 select...
Page 23  Set of DIP Switches 2 (Set of 8) The DIP SW 2 on the circuit board configures additional features at the time of installation, such as temperature control modes. Switch Function Setting Return Water 1-ON Temperature Control Supply Water 1-OFF Reserved Reserved...
Page 24 Setting the Front Panel DIP Switches Before change the settings, lift the rubber cover to access the front panel DIP switches. S/W 2 S/W 1  Set of DIP Switches 1 (Set of 10) The DIP SW 1 on the front panel configures the temperature ufnit, well pump, and high altitude settings. SW1 NO.
Page 25  Set of DIP Switches 2 (Set of 2) The DIP SW 2 on the front panel configures the gas type setting. SW1 NO. Application Setting Remarks Reserve Natural Gas 2-OFF Gas type Propane Gas 2-ON NCB Service Manual Version 1.0...
Page 26: Measuring The Inlet Gas Pressure
4.2 Measuring the Inlet Gas Pressure 4. Remove the boiler front cover by loosening the 4 Phillips head screws securing it to the case. WARNING The boiler cannot function properly without sufficient inlet gas pressure. Measuring the inlet gas pressure should be performed by a licensed professional only.
Page 27: Gas Pipe Sizing Tables (Referenced From 2012 National Fuel Gas Code)
6. Re-open the manual gas valve and check for leaks. 8. When the boiler reaches its maximum firing rate, check the inlet gas pressure reading on the manometer. The gas 7. Open multiple fixtures that have high flow rates, such as pressure must fall within the proper operating range bathtub and shower faucets, to allow the boiler to operate indicated in the previous page and also in the...
Page 28 in Cubic Feet (ft ) per Hour (0.60 Specific Gravity; 3.0” WC Pressure Drop). Contact your gas supplier for BTU/ft ratings. Use 1,000 BTU/ft3 for simplified calculations. This table is recommended for supply pressures of 6” WC or greater. Length (including fittings) Pipe 100' 125'...
Page 29: Gas Conversion
WARNING This conversion kit shall be installed by a qualified service agency* in accordance with Navien America’s instructions and all applicable codes and requirements of the authority having jurisdiction. The information in these instructions must be followed to minimize the risk of fire or explosion or to prevent property damage, personal injury or death.
Page 30 7. Remove the PCB assembly. 10. Once the gas inlet pipe is detached from the gas valve, find location B - the connection above the gas valve where it is attached to the fan motor assembly. Carefully remove the four screws by hand using a Phillips screwdriver and pull the gas valve away from the fan assembly to access the gas orifice.
Page 31 DANGER WARNING See Figure 5. Inspect the O-ring between the gas valve  DO NOT adjust or attempt to measure gas valve outlet and gas valve inlet adapter whenever they are pressure. The gas valve is factory-set for the correct disassembled.
Page 32 Low fire Boiler Fuel DANGER  When conversion is required, be sure to set the Front NCB-180 10.2 10.8 Panel DIP switches according to the supply gas type.  Failure to properly set the DIP switches could cause carbon monoxide poisoning, resulting in severe NCB-210 personal injury or death.
Page 33 Figure 8. Set Screw Location Model Kit Part No. Gas Type Offset NAC-01 -0.03"±0.01" NOTE NCB-180 NAC-100 -0.04"±0.01" The set screw is located behind the screw-on cover. This NAC-02 -0.02"±0.01" must be removed first. NCB-210 NAC-200 -0.04"±0.01"...
Page 34 Fully open a hot water fixture and set the boiler to Once the CO or offset values have been confirmed, apply the operate at 1-stage MIN mode (refer to page19 and included conversion stickers to show that the appliance has page 54).
Page 35: The Front Panel
4.4 The Front Panel The front panel allows you to adjust the water temperature and view the operating status or error codes. Remove the protective sheet from the front panel before using it. 4.4.1 LCD Display DISPLAY (Icon) Function Remarks Displays Heating icon upon heating demand (Space Heating mode) Heating...
Page 36: Buttons
Segment Status Display Function Remarks Shown while waiting for a response from the Main Controller when WAIT the Boiler performs an error test or error history load Shown on Error Reset Shown on deleting the error history and parameters. Shown on Factory Reset INIT 4.4.2 Buttons Button...
Page 37 Long Key Combination Function Remarks [Power] long key Power ON / OFF (300msec) Must be in normal mode or Error Display [Mode] long key Error history display mode (2 seconds) [Reset] long key Individual deletion of Error History / Tech Data Works only at the relevant mode (5 seconds) Must be in normal mode...
Page 38: Turning The Boiler On Or Off
4.4.3 Turning the Boiler On or Off ※ When the power is first applied, please turn the panel segments and icons on for 3 seconds (in order to check LCD To turn the boiler on or off, press the [Power] button. defect) ※...
Page 39 Item Description Display When the current supply water temperature is 120℉ and the water pressure is 12.3psi, the image below repeats at 5 second intervals (Fahrenheit specification) 5 sec flashing Normal Operating mode with 1. Normal status power On When the supply water temperature is 60.0℃ and its water pressure is 12.3psi, the image below repeats at 5 seconds intervals.
Page 40: Error Display And Reset
4.4.5 Error Display and RESET 4.4.6 Adjusting the Space Heating Temperature 1. When an error higher than Level 2 occurs (the Boiler may The boiler is set to 140°F (60°C) by default. To adjust the space stop operation or only has basic functions), the Boiler heating water temperature: enters <Error Display mode>...
Page 41: Adjusting The Dhw Temperature
2. Press the Mode button twice. The DHW mode icon turns 3. You can adjust the temperature while the display is flashing. Once the display stops flashing, the temperature setting is stored. NOTE  Take note of the original heating temperature in case you want to restore it to the default.
Page 42: Viewing Basic Information (For Homeowner)
4.4.8 Viewing Basic Information (For Homeowner) To view information about the boiler, press the [Mode] button three times. “INFO” will appear in the display. Press the [+] or [–] buttons to switch between the information types. Item Description Display For Celsius (℃) mode; ex) at 60℃ Display of the current space (A) Space heating supply water heating outgoing water...
Page 43 Item Description Display Using sensor GPM flow rate display Display of the current flow rate ex) 10.2GPM (E) Flow rate Minimum display unit (0.2 Gal/min or l/min) Outdoor Temperature display for Celsius (℃) mode with optional sensor, ex) at 15℃ (F) Outdoor air temperature Display of current outdoor (with optional Outdoor...
Page 44: Error Occurrence History Display
4.4.9 Error occurrence history display NOTE 1. At the <Normal operation mode> or <Error history display mode>, press the [Info] button for over 2 seconds to access  While in <ERROR HISTORY DISPLAY MODE> the first the error history mode. digit indicates the history of the error with 0 being the The most recent error will be displayed first.
Page 45: Information Display (For Servicer)
4.4.10 information display (for servicer) 1. At the <Normal operation mode>, press the [Diagnostic] button once for 5 seconds to access the service information display. 2. Whenever the [+] / [-] button is pressed, the Information Data items are increased/decreased and displayed. 3.
Page 46 Item Description Display Using sensor GPM flow rate display Display of the current flow rate ex) 10.2GPM (E) Flow rate Minimum display unit (0.2 Gal/min or l/min) Outdoor Temperature display for Celsius (℃) mode with optional sensor, ex) at 15℃ (F) Outdoor air temperature (with optional Outdoor Display of current outdoor temperature...
Page 47 Item Description Display % Heat capacity display in percentage Display of current heat capacity % ex) 100%, (J) Heat Capacity range: 50~100% Default : 100% Displays the flame by flame detection AD value Display of flame detection current AD (0~255) , ex) 200 value (K) Flame State Flame ON : Below 70...
Page 48 Item Description Display ex) Capacity 180, condensing for the American market Currently set model and capacity display ex) Capacity level 240, for the Korean market (Q) Model and Capacity The 2nd & 3rd digits represent the model and the 4th digit represents the type of market.
Page 49: Special Parameter Mode
4.4.11 Special Parameter mode You can modify parameter settings for boiler operations, such as the space heating and DHW temperature ranges, in different operating conditions. Follow the instructions below to access the Special Parameter mode and change the available settings CAUTION Parameters must be set by a qualified professional with an extensive understanding of the boiler system.
Page 50 CAUTION  If you enter an incorrect password 10 times or make no input 5 minutes, the boiler will return to the Normal Mode.  To return to the previous mode, press the Reset button.  The Factory default password is “1234” ...
Page 51 Item Description Display For Celsius (℃) mode; ex) at - 10℃ This mode is used to configure the lowest outdoor temperature. The boiler will operate at the high end of the supply or return set-point range at this outdoor temperature. For Fahrenheit (℉) mode;...
Page 52 Item Description Display For Celsius (℃) mode; ex) This menu is used to configure the circulation pump freeze protection at 10℃ temperature. When the space heating supply temperature stays below the set value for longer than 10 seconds, the boiler runs the circulation pump to prevent (G) Pump Freezing freeze damage (the pump runs for 10 minutes, then stops for 1 minute).
Page 53 Item Description Display For Celsius (℃) mode; ex) at 0℃ During space heating, the boiler turns off the burner when the space heating supply temperature meets or exceeds the burner-off temperature. (L) CH Burning OFF Setting range Default Differential For Fahrenheit (℉) mode; ex) at 0℉...
Page 54 Item Description Display For Celsius (℃) mode; ex) This menu may be used to make changes to the maximum return at 30℃ temperature range the Return Control mode is in use. When configuring the Custom mode in the Outdoor Reset Control mode, the return (Q) Return temperature changes based on the return absolute MIN temperature Absolute MIN...
Page 55 (2) Error Checking mode 1. While in <Special Parameter mode>, press the [+] / [-] button and then press the [Mode] button once “2.TST” is displayed on the front panel. 2. After accessing <Error Checking Mode>, make sure that the boiler is not operating (stop flow) 3.
Page 56 Component Test Performed Display Method The current APS value and the current RPM value are Gradually increase / decrease the speed repeatedly displayed at intervals of 2 seconds. of the fan motor starting from 0 RPM to full speed and back down to 0 RPM Displays On or Off according to pump status Cycles the pump 10 seconds ON and 5 Pump...
Page 57 (3) Operation conditions Settings 1. While in <Special Parameter mode>, press the [+] / [-] button and then press the [Mode] button once when “3. OPR” is displayed on the front panel. 2. Whenever the [+] / [-] button is pressed, it increases / decreases the operation condition and flashes at intervals of 500msec. If the condition is not changed for 3 seconds, it works at the displayed operation condition.
Page 58: Resetting The Boiler (Factory Reset)
4.4.12 Resetting the Boiler (Factory Reset) 4.5 Version Display If an error message appears, you can try resetting the boiler to Press the [Diagnostic] button for more than 10 seconds at resolve the problem. To reset the boiler, press the Reset <Power Off mode>...
Page 59: Ladder Diagram
4.7 Ladder Diagram NEUTRAL Relay 1 FILTER Relay 2 VENTURI Relay 3 IGNITER Relay 4 PUMP Relay 5 3 WAY Primary Speed Control Secondary Auto Water Supplement Flame Rod Flow Sensor Hall Sensor DHW Inlet Thermistor 1 DHW Outlet Driving Circuit Thermistor 2 Heating Supply Relay 3...
Page 60: Electrical Diagnostic Point & Wiring Diagram
4.8 Electrical Diagnostic Point & Wiring Diagram Extern. power...
Page 61 Point Function CN No. Wire Color Normal Value Check DHW Inlet Temperature CN13 Voltage changes according to BLUE-BLUE DC 0~5V Sensor temperature. HEATING Return CN13 Voltage changes according to BLUE-BLUE DC 0~5V Temperature Sensor temperature. DHW outlet Temperature CN13 RED-RED Voltage changes according to DC 0~5V Sensor...
Page 62 Point Function CN No. Wire Color Normal Value Check Confirm appropriate power source. Power Input WHITE-BLACK AC 97~138V Confirm the FUSE. Confirm the circuit breaker. CN17 ON : AC 97~138V Confirm voltage when the unit is Igniter BLUE-BLUE OFF : 0V igniting.
Page 63: Key Components Description
4.9 Key Components Description 4.9.1 PCB Part Check Point To control each component and also to check the overall performance of the unit. Function Malfunctioning PCB. Failure Event A component may not operate within the unit and could produce an error code. In most cases of PCB Effects failure, the whole unit will not operate until the problem is resolved.
Page 64: High Limit Switch
4.9.2 High Limit Switch Check Point Check Point 1. Overheat prevention switch. 2. If the unit detects extremely high temperatures, it will automatically trip and shut down the unit. Function 3. Excessively high water temperatures (more than 197.6 °F or 92 °C) in heat exchanger will activate the high limit switch.
Page 65: Thermistor
4.9.3 Thermistor Part Check Point Measure Hot water, Cold water, Space heating outlet and inlet temperatures in the boiler. Function Unable to properly measure water temperature within the boiler. Failure Event 1. If any of the thermistors fail, an error code appears before starting operation. Effects 2.
Page 66: Fan Motor
4.9.4 Fan Motor Part Check Point To provide combustion air into the burner and to purge exhaust flue gas. Function To maintain 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 67: Flame Rod Assembly
4.9.5 Flame Rod Assembly Part Check Point To ignite gas by repeatedly discharging a high voltage spark to the main burner until gas ignites. Function 1. Unable to ignite during the ignition process. Failure Event 2. Produces multiple unsuccessful attempts to ignite. 1.
Page 68: Ignition Transformer
4.9.6 Ignition Transformer Part Check Point To ignite gas by repeatedly discharging a high voltage spark to the main burner until gas ignites. Function 1. Unable to ignite during the ignition process. Failure Event 2. Produces multiple unsuccessful attempts to ignite. 1.
Page 69: Aps
4.9.7 APS Part Check Point Detecting the air pressure entering the burner system. Function 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 70: Main Gas Valve
4.9.8 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. Unable to open/close Failure Event 1.
Page 71: Burner
4.9.9 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 72: Flow Sensor
4.9.10 Flow Sensor Part Check Point To detect water flow in GPM (Gallons Per Minute) for steady hot water temperatures. Function 1. Unable to detect or measure water flow rate. Failure Event 2. Damage to and/or water leakage from the water flow sensor. 1.
Page 73: Primary Heat Exchanger
4.9.11 Primary Heat Exchanger 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 74: Secondary Heat Exchanger
4.9.12 Secondary Heat Exchanger 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 as well as inside the combustion chamber which minimizes heat loss. 1.
Page 75: Dhw Heat Exchanger
4.9.13 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 heating water and tap water are exchanged so that hot water is available 1. Water leakage through a crack. Failure Event 2.
Page 76: Circulation Pump
4.9.14 Circulation Pump Part Check Point 1. Pump operates when using internal or external hot water circulation. Function 2. Internal circulation will minimize the effect of temperature fluctuations and external circulation delivers hot water to fixtures quickly resulting in water conservation. Unable to detect or measure water flow rate when the pump is called to operate.
Page 77: 3-Way Valve
4.9.15 3-Way Valve Part Check Point Diverts the water from the space heating system to the DHW plate heat exchanger and back based on Function input from DHW flow sensor and PCB. 1. No hot water in space heating mode. Failure Event 2.
Page 78: Water Pressure Sensor
4.9.16 Water Pressure Sensor Part Check Point They are suitable for analyzing water pressure ratios in heating. Function Unable to detect or measure to change water pressure Failure Event Effects Water filling system does not operate automatically E351, E352, E353 Error Code 1.
Page 79: Auto Feeder Valve
4.9.17 Auto feeder Valve Part Check Point Detect low and high water pressure using the electronic water pressure sensor If water pressure is low, Function Water filling system operates automatically 1. Water filling system does not operate automatically. Failure Event 2.
Page 80: Troubleshooting
5. Troubleshooting 5.1 Error code classification Classification Error Code Error Level Function Self-diagnostic/Action E003 Ignition failure Manual RESET E004 False flame detection Auto RESET E012 Flame loss Manual RESET E016 Overheating of heat exchanger Manual RESET Exhaust Overheat: exhaust limit switch shuts down the Combusition Manual RESET unit when the flue temperature exceeds 230℉(110℃)
Page 81: Error Code List
5.2 Error Code List Error Code Function Self-diagnostic/Action 1. Check to see if the main gas supply valve is open. 2. Check that the power is “ON”. Ignition failure E003 3. Check the igniter for spark. 4. Tighten the ground connection screws on heat exchanger. 1.
Page 82 Error Code Function Self-diagnostic/Action Abnormal Auto feeder valve (make-up water) Check the auto feeder valve E351 High water pressure Check the auto feeder valve E352 Abnormal operation: water pressure sensor Check the water pressure sensor. E353 1. Check the thermistor. Hot water outlet: thermistor open or short E407 2.
Page 83: 003Error
5.2.1 003Error Error occurrence conditions and check items Error Description In the case of an ignition failure, the boiler will attempt ignition 10 times. If no flame is detected, the E003 system displays the error message 003E (manually cleared) on the Front Panel. Ignition failure 1.
Page 84 Scenario2 Does the main Is gas valve operating Check connector gas valve have proper normally? voltage? Check the voltage between #1 and #2 of CN 16: 22-24 VDC Check the voltage between #1 and #3 of CON 4: 22-24 VDC (see page 56 for Wiring Diagram) Check that gas valve is Is gas valve open?
Page 85 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 86 Failure Cause Check method mode Bracket 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 ...
Page 87 Failure Cause Check method mode 1. Check the primary/secondary power supply to the main gas valve. Check, with a multi-meter, if the input power is DC 22-24 V.  2. Replace the PCB if power is not supplied. Main gas valve 3.
Page 88 Failure Cause Check method mode 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 89: 004Error
5.2.2 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 90: 012Error
5.2.3 012Error Error occurrence conditions and check items Error Description If the system detects loss of flame during combustion, the system stops supplying fuel, attempts to restart, E012 counts the incidents of flame loss, and if the incident occurs 20 times consecutively displays 012E (manually Flame loss cleared) on the front panel.
Page 91 Check method Fault Possible Causes Check method 1. 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.  2. While the static pressure is normal, the use of another gas appliance may cause a possible drop in gas pressure to the unit.
Page 92 Fault Possible Causes Check method Model Gas Type Offset -0.04"±0.01" NCB-180 -0.03"±0.01" Flame loss and noise occurs after -0.04"±0.01" NCB-210 ignition -0.02"±0.01" -0.04"±0.01" NCB-240 -0.02"±0.01" Digital pressure manometer Offset value for low fire Check the offset values for low fire Flame loss will occur if the gas orifices are clogged.
Page 93: 016Error
5.2.4 016Error Error occurrence conditions and check items Error Description If the overheat controller on the heat exchanger is initiated during combustion/standby of the boiler, the E016 system displays the 016E (manually cleared) message on the front panel. The boiler switches into Lock-Out, Bimetal and performs post-purge continuously and operates the pump.
Page 94 Check method Fault Possible Causes Check method Defective Check if the contact point of the overheat controller is defective. overheat Use a multi-meter to see if the resistance is normal (0.3Ω) or abnormal (∞).  controller Defective safety device Overheat controller Check if the overheat controller wire is disconnected ( Normal resistance : 0.3Ω...
Page 95: 030Error
5.2.5 030Error Error occurrence conditions and check items Error Description If the overheat controller on the top of the exhaust duct is initiated, the system displays the heat exchanger bimetal overheat message 030E (cleared manually) on the front panel. The boiler switches into Lock-Out, and performs post-purge continuously and operates the pump. Overheating controller operates when the temperature exceeds 230°F (110°C) for 10 minutes or over.
Page 96 Check method Fault Possible Causes Check method 1. The error occurs due to high exhaust gas temperature caused by a damaged or Damaged or clogged heat exchanger. Heat exchanger clogged heat overheated 2. Flush the heat exchanger to remove scale deposits. exchanger 3.
Page 97: 046Error
5.2.6 046Error Error occurrence conditions and check items Is heat exchanger Check connector thermistor normally ( #3 and #4 of CN 13) operating? Is resistance 1 step: Flushing, Clean Filter within normal range? 2 step: Try to restart (refer to page 62) 3 step: Replace PCB Replace heat exchanger thermistor.
Page 98: 060Error
5.2.8 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 Venturi E060 malfunctions. Dual Venturi error The boiler switches into Lock-Out, and performs post-purge continuously and operates the pump. 1.
Page 99 Check method Fault Possible Causes Check method Defective Dual 1. Disconnect all cables from the Dual Venturi. Venturi cable or 2. Using a multi-meter, test the Dual Venturi electrical wiring. harness 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 100: 109Error
5.2.9 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: E109 1. If the RPM remains low or close to 0, the system determines RPM error, and the boiler switches into Lock- Fan motor RPM Out (gas valve and ignition transformer locked).
Page 101 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 the No fan operation unit and then wait for at least 10 seconds before proceeding.) 3.
Page 102: 110Error
5.2.10 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 103: 205Error
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: Abnormal flow of 110E Air supply / exhaust vent for any blockages.
Page 104 Check method Fault Possible Causes Check method Defective Check if the temperature sensor is open and if the connector is connected properly. temperature sensor connector Defective sensor Check the resistance of the temperature sensor. (Defective if it is 30kΩ or higher) Replace the temperature sensor if the resistance value is abnormal.
Page 105: 218Error
5.2.12 218Error Error conditions and Check Items Error Description E218 Heat exchanger If an error (open: 14°F (-10°C) or lower) in the heat exchanger input temperature sensor is detected, the system input displays the 421E error on the front panel. If this occurs, the boiler initiates shutdown. temperature sensor open 1.
Page 106 Check method Fault Possible Causes Check method Defective Check if the temperature sensor is open and if the connector is connected properly. temperature sensor connector 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 107: 351Error
5.2.13 351Error Error conditions and Check Items Error Description If the water pressure sensor senses low water level as the heating pipe pressure is low, the system stops E351 operation of the boiler, and refills water automatically. Abnormal Auto If water is supplied by auto feeder valve open over 5 minutes, the error(E351) is detected and displayed on the feeder valve front panel.
Page 108: Water Is Not Refilled
Check method Fault Possible Causes Check method Water is not Cold water valve is Turn on cold water tap and check if the valve works or is frozen. Refilled closed or frozen 1. Check the auto feeder valve filter if water is not refilled. Defective auto feeder 2.
Page 109: 352Error
5.2.14 352Error Error conditions and Check Items Error Description Upon receiving a signal from the water pressure sensor, the system displays the error(E352) on front panel. E352 High water level error if the water level of 56.6PSI or higher continues 3 seconds. High water Error is automatically cancelled if water level is 43.5PSI or lower.
Page 110: 353Error
5.2.15 353Error Error conditions and Check Items Error Description E353 If an error (under 0.3V or over 2.8V) in the water pressure sensor is detected continuously for 3 seconds, The Abnormal water system displays the error message E353 on the front panel. If this occurs, the boiler initiates shutdown. pressure sensor 1.
Page 111: 407Error
5.2.16 407Error Error conditions and Check Items Error Description E407 If an error (open: 14°F (-10°C) or lower) in the DHW Outlet Elbow input temperature sensor is detected, Hot water outlet the system displays the 407E error on the front panel. thermistor open or short 1.
Page 112 Check method Fault Possible Causes Check method Defective Check if the temperature sensor is open and if the connector is connected properly. temperature sensor connector 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 113: 421Error
5.2.17 421Error Error conditions and Check Items Error Description E421 If an error (open: 14°F (-10°C) or lower) in the DHW Outlet Elbow input temperature sensor is detected, Cold water inlet the system displays the 421E error on the front panel. thermistor open or short 1.
Page 114 Check method Fault Possible Causes Check method Defective Check if the temperature sensor is open and if the connector is connected properly. temperature sensor connector 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 115: 439Error
5.2.18 439Error Error occurrence conditions and check items Error Description As one or more units are operating in the cascade system, if no flow is detected during DHW using, the system E439 considers it as a defective flow sensor. The system displays 439E (cleared manually) on the front panel and Flow sensor error switches the unit operation into the Lock-Out mode (gas valve and ignition transformer locked).
Page 116 Check method Fault Possible Causes Check method 1. Check if the cold water line is frozen. Cold water supply No hot water flow error 2. Check if the cold water filter is clogged. 1. Check the current flow displayed on the front panel. If the flow sensor is defective, the displayed flow value is 0.0 while water ...
Page 117: 515Error
5.2.19 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 system displays E515 error 515E (cleared manually) on the PCB. 1. Defective PCB 2.
Page 118: 517Error
5.2.20 517Error Error occurrence conditions and check items Are the DIP S/W on the Reset the unit PCB properly set? Change the DIP S/W to the proper settings 5.2.21 594Error Error occurrence conditions and check items Error Description If the communication is abnormal in parts of PCB, the system displays E594 on the PCB. E594 error Check the PCB.
Page 119: 736Error
5.2.23 740Error Error conditions and Check Items Error Description E740 If an error (under 2.2k Ω or over 122.2k Ω ) in the outdoor sensor is detected continuously for 3 seconds, The Abnormal system displays the error message E740 on the front panel. If this occurs, the boiler changes the control mode outdoor sensor from Reset Curve Mode to Normal Mode.
Page 120: 782Error
5.2.24 777Error Error conditions and Check Items Is the LWCO Check the factory installed jumper installed properly? on the LWCO theminals (CN24) Check the connecting terminals Does the power supply (CN25) LWCO properly? Check LWCO 5.2.25 782Error Error occurrence conditions and check items Is the wiring from the step: Reset the unit.
Page 121: 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 122: Water Temperature Issue
5.3.2 Water Temperature Issue Error type Cause Check method Front panel power Hot water does not run if the front panel is switched off. The boiler does not work due to the defective flow sensor. The flow sensor impeller will not rotate if it contains excessive scale or debris. ...
Page 123: Circuit Breaker Operation
5.3.3 Circuit breaker operation Error type Cause Check method The circuit breaker trips immediately as soon as the power cord is plugged in the receptacle. Power supply Check the sheath of power cord, or if there is short-circuit. Check the components in order from the power transformer to the PCB. If the circuit breaker operates after repairs check the wiring of each part.
Page 124: Replacement Of Parts
6. Replacement of Parts 6.1 Replacement Procedure 6.2 Components Replacement Instructions CAUTION 6.2.1 PCB 1. When performing maintenance and/or servicing the boiler, always turn off the electric power, gas and 1. Turn off the gas supply to the unit. water shut-off valve. Wait for the boiler to become 2.
Page 125: Fuse
7. Remove the old PCB and replace it with the new part. 6.2.3 Fan Motor (Combustion Air) 8. Reattach all wiring connectors to the PCB. 1. Turn off the gas supply to the unit. 9. Set the proper DIP S/W settings on the PCB (refer to 2.
Page 126: Flame Rod
8. Remove the four screws from the bottom of the fan 6.2.4 Flame Rod assembly. 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.
Page 127: Ignition Transformer
7. Pull out the Ignition Transformer. NOTE 8. Replace the old Ignition Transformer with the new part, and then use the 2 screws to secure the part. Always use new factory gaskets included with the flame 9. Reconnect the Ignition Transformer insulated cables to rod when replacing the part onto the burner assembly.
Page 128: Main Gas Valve
5. Remove the hose from the air pressure sensor. 5. Remove the 2 screws and disconnect the wiring connector at the gas valve. Figure 13 Figure 12 6. Remove the 2 screws located at the bottom of the unit that are attached to the gas valve. 6.
Page 129: Condensate Trap
7. Remove the 4 screws directly from the bottom of the gas 6.2.8 Condensate Trap valve to remove the elbow. 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.
Page 130: Flow Sensor
6.2.9 Flow Sensor 8. Pull out the flow sensor. 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. Drain all water from the appliance. 4.
Page 131: 3-Way Valve
5. Remove the stainless nut, fastener and circulation pump 11. Reinstall the pump drain plug at the bottom of the unit. wiring connector (Figure 22). 12. Reconnect the wiring connector at the pump. 13. Install the Main PCB back onto the unit by using the four screws.
Page 132: Water Pressure Sensor
6. Remove the two screws on the bottom of case. 6.2.13 Space Heating Strainer (Filter Cleaning or Strainer Replacement) 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.
Page 133: Auto Feeder Valve
6.2.14 Auto Feeder Valve 6. Remove the two fasteners at the DHW exchanger. 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.
Page 134: Components Diagram And Part List
7. Components Diagram and Part List 7.1 Case Assembly Description Part # Remark Intake Air Duct Assembly 30008662B Exhaust Pipe Assembly 30008673A Case 20027375A Intake Air Filter 20007668A Air Pressure Sensor 30010346A 30012262A Front Panel 30012269A Cover 30012276A...
Page 135: Burner Assembly
7.2 Burner Assembly NCB Service Manual Version 1.0...
Page 136 Description Part # Remark Damper 30008825A O-Ring (G50) 20003019A Fan Bracket 20022095A Siphon 30012280A 30010353A NCB-180 Burner Chamber Ass'y 30008440A NCB-210/240 Ignition Transformer 30010455A 20021677A NCB-180 Burner Packing 20021672A NCB-210/240 30012322A NCB-180 Heat Exchanger Ass'y 30012321A NCB-210 30012317A NCB-240 Thermistor (Exhaust)
Page 137: Waterway Assembly
7.3 Waterway Assembly Description Part # Remark 30008181A NCB-180 DHW Heat Exchanger 30005017A NCB-210/240 Thermistor 30008366A O-Ring (P18) 20006954A DHW Outlet Elbow 30012328A Packing 20006852A Thermistor 30008366A NCB Service Manual Version 1.0...
Page 138 Description Part # Remark DHW Outlet Adpator 30003747A DHW Flow Sensor 30012033A O-Ring (P14) 20006952A DHW Cold Water Adaptor 30010317A O-Ring (P20) 20017212A DHW Cold Water Filter Air Vent 30012277A Auto Fill Valve 30012241A O-Ring (P16) 20011438A Fastener 20007859A Auto Fill Valve Adaptor 3-Way Outlet Adaptor B 30012332A Fastener...
Page 139: Fan (Gas) Assembly
7.4 Fan (Gas) Assembly NCB Service Manual Version 1.0...
Page 140 NCB-210/240 20019142A NCB-180 Silence 20023829A NCB-210/240 20023861A NCB-180 Silence Adaptor 20019141A NCB-210/240 Venturi Packing 20022660A NCB-180 20024159A NCB-180 (NG) 20024190A NCB-210/240 (NG) Gas Orifice 20019144A NCB-180 (LP) 20024189A NCB-210/240 (LP) O-Ring (P34) 20019090A Gas Adapter 30008431A O-Ring (P20) 20006934A 30012338A...
Page 141: 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 maintance recommended that the boiler is serviced annually.  Check boiler area Daily  Check pressure / temperature gauge CAUTION ...
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This manual is also suitable for:

Ncb-210 Ncb-240

Navien NCB-180 Service Manual

1 Safety Information

2 Product Information

3 Technical Data

4 System Details

5 Troubleshooting

6 Replacement of Parts

7 Components Diagram and Part List

8 Inspection and Maintenance Schedule

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Troubleshooting

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