Navien NHB-055 Service Manual
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Navien NHB-055 Service Manual

Nhb series condensing boilers
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See also: User's Information Manual , Operation & Installation Manual
Service Manual
NHB Condensing Boilers
Model
NHB-055
NHB-080
NHB-110
NHB-150
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 NHB-055

  • Page 1 Service Manual NHB Condensing Boilers Model NHB-055 NHB-080 NHB-110 NHB-150 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 1.00 First Issue March / 26 / 2015 1.0 Reviewed BY : Paek Ji Ho, NHB Service Manual Version 1.0...

  • Page 3: Table Of Contents

    Contents 1. Safety Information 4.5 Version Display 4.6 Error Code 1.1 Safety Definitions 4.7 Ladder Diagram 1.2 Safety Symbols 4.8 Electrical Diagnostic Point & Wiring Diagram 1.3 Symbols Used in the Instructions 4.9 Key Components Description 1.4 Safety Precautions 4.9.1 PCB 4.9.2 High Limit Switch 2.
  • Page 4 7. Components Diagram and Part List 5.2.15 278Error 5.2.16 279Error 7.1 Case Assembly 5.2.17 291Error 7.2 Heat Exchanger and Waterway Assembly 5.2.18 302Error 7.3 Combustion Parts Assembly 5.2.19 352Error 5.2.20 353Error 8. Inspection and Maintenance Schedule 5.2.21 515Error 8.1 Annual Servicing 5.2.22 517Error 8.2 Maintenance Report 5.2.23 594Error...
  • Page 5 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 requirements shall...

  • Page 6: Navien Warranty

    Warranty Period Warranty Exclusions Navien products come with a limited warranty covering labor, Navien’s Limited Warranty shall be void in the event of an parts and the heat exchanger. The following warranty periods occurrence of any of the following: begin to run from the date of original installation. The date of Improper installation, failure to install in strict compliance with ●...
  • Page 7 Installation procedures at normal manifold pressure. For installation instructions at altitudes higher than 4,500 ft, please contact Navien. *Cet appareil est certifié pour une utilisation à des altitudes de 0 à 4,500 pieds (1,370 m) conformément aux toutes les procédures d’installation à...
  • Page 8 Abbreviations and Definitions Abbreviation Definition General name of NHB-055, NHB-080, NHB-110 and NHB-150 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...

  • 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 DO NOT use parts other than those specified for this ● Navien Inc. is not liable for any property damage and/or equipment. personal injury resulting from unauthorized conversions. DO NOT operate the boiler if you feel something is wrong ●...
  • 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 NHB Series gas boiler. This appliance is fully modulating and provides central heating. Depending on the heat capacity, each model is divided into four types; 055, 080, 110 and 150.

  • 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 Air Filter Air Vent Connection Flue Duct LWCO Front Panel Space Heating Supply Power Switch NHB Service Manual Version 1.0...
  • Page 15 Ignition Teansformer Metal fiber Premix Buener Igniter & Flame Rod Primary Heat Exchanger Mixing Gas Guide Secondary Heat Exchanger Fan & Motor Gas Valve Dual Venturi Gas Connection Condensate Trap Space Heating Return Version 1.0 NHB Service Manual...

  • 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 Flame Rod, APS, Ignition Operation Detector Water Temperature High Limit Switch, Safety Devices Exhaust Temperature High Limit Sensor, Water Pressure Sensor Navien Manifold System, Condensate Neutralizer Kit, Zone Controller, Accessories System Supply / Return Temperature Sensors, Condensate Neutralizer Water Pressure...

  • Page 18: Dimensions

    Condensate Outlet Gas Connection Space Heating Supply 1 in Overhead View Supply Connections 15.9” (405 mm) 6.6” (170 mm) 4.5” (115 mm) 15.8” (401 mm) 6” (152 mm) 17.3” (440 mm) * NHB-055/080: 11.8” (300 mm) NHB Service Manual Version 1.0...

  • Page 19: System Details

    4. System Details 4.1 Setting the DIP Switches Set of PCB DIP Switch 1 (6 switch unit) The DIP SW 1 on the circuit board configures the operation status and model / capacity settings. CAUTION Do not remove the front cover unless the power to the boiler is turned off or disconnected.

  • Page 20: Front Panel Dip Switches

    4.1.2 Front Panel DIP Switches Set of PCB DIP Switch 2 (8 switch unit) The DIP SW 2 on the circuit board configures the temperature Set of Front Panel DIP Switch 1 (10 switch unit) control modes, country, and enables or disables the space heating thermostat.

  • Page 21: Measuring The Inlet Gas Pressure

    4.2 Measuring the Inlet Gas Pressure Set of Front Panel DIP Switch 2 (2 switch unit) The DIP SW 2 on the front panel configures settings for the type of gas. WARNING Before changing the settings, lift the rubber cover to access the front panel DIP switches.
  • Page 22 2. Turn on the boiler. On the front Panel, press and hold the 10. Loosen the screws indicated in the figure below and connect a Diagnostics Button for over5 seconds until “1.PAR” is displayed. manometer to the pressure port. Reset the manometer to zero before use.

  • Page 23: Gas Pipe Sizing Tables

    4.2.1 Gas Pipe Sizing Tables The following tables are referenced from 2012 National Fuel Gas Code 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; 0.5 in WC Pressure Drop). Contact your gas supplier for BTU / ft ratings.
  • Page 24 Maximum Liquefied Propane Delivery Capacity In Thousands of BTU / H (0.5” WC Pressure Drop) Length (including fittings) Pipe Size 10 ft. 20 ft. 30 ft. 40 ft. 50 ft. 60 ft. 70ft. 80ft. 90ft. 100ft. 125ft. 200 ft. 250 ft. (3 m) (6 m) (9 m)

  • Page 25: Gas Conversion

    Ø2.80 WARNING NHB-080 Ø4.20 Ø3.55 Ø3.40 Ø2.80 This conversion kit shall be installed by a qualified service agency* in accordance with Navien’s instructions and all NHB-110 Ø4.25 Ø5.00 Ø3.45 Ø3.85 applicable codes and requirements of the authority having NHB-150 Ø4.60 Ø6.90...
  • Page 26 6. Loosen the three screws indicated below in Figure 2 and 3. 8. With the internal components exposed, locate the gas inlet pipe and the gas valve in the middle of the unit, as shown in Figure 4. Gas Inlet Pipe Gas Valve Figure 2.
  • Page 27 Do not over tighten as this may damage or crack the Navien NHB boilers are shipped ready to fire natural gas components. ONLY.
  • Page 28 Figure 9 Insert the Analyzer High fire Low fire Model Fuel DANGER NHB-055 10.2 10.8 When conversion is required, be sure to set the Front Panel ● DIP switches according to the supply gas type. Failure to properly set the DIP switches could cause carbon NHB-080 ●...
  • Page 29 Model Kit Part No. Gas Type Offset Figure 10. Set Screw Location NAC-N1 -0.04 in ±0.01 in NHB-055 NAC-L1 -0.03 in ±0.01 in NAC-N2 -0.04 in ±0.01 in NOTE NHB-080 NAC-L2 -0.02 in ±0.01 in The set screw is located behind the screw-on cover.
  • Page 30 c. Activate multiple zones and set the boiler to operate at 19. Once the CO or offset values have been confirmed, apply the 1-stage MIN mode (refer to "(3) Operation Conditions included conversion stickers to show that the appliance has Settings"...

  • Page 31: The Front Panel

    4.4 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. 4.4.1 LCD Display DISPLAY (Icon) Function Remarks Displays Heating icon upon heating demand (Space Heating mode) Heating Displays Hot Water icon upon hot water demand (DHW setting mode) Hot Water...

  • Page 32: Buttons

    Segment Status Display Function Remarks Shown while waiting for a response from the Main Controller when the Boiler WAIT performs an error test or error history load Shown on Error Reset Shown on deleting the error history and parameters. INIT Shown on Factory Reset 4.4.2 Buttons Button...
  • Page 33 Long Key Combination Function Remarks [Power] long key (300msec) Power ON / OFF Must be in normal mode or Error Display mode [Mode] long key (2 seconds) Error history display Works only at the relevant mode [Reset] long key (5 seconds) Individual deletion of Error History / Tech Data Must be in normal mode 1.

  • Page 34: Turning The Boiler On Or Off

    4.4.3 Turning the Boiler On or Off Item Description Display To turn the boiler on or off, press the [Power] button for All displays off except status icons Power Off status with 0.3 seconds. (the status icon is shown normally power Off according to function status) * When the power is first applied, please turn the panel segments and icons...
  • Page 35 9. Entering <Error History mode> is available via Item Description Display <Normal Operating mode>. When the current supply water temperature is 120°F and its Item Description Display water pressure is 12.3psi, the When the current supply water image below repeats at 5 seconds temperature is 120°F and the water intervals.

  • Page 36: Error Display And Reset

    4.4.5 Error Display and RESET 4.4.6 Adjusting the Space Heating Temperature The boiler is set to 140°F (60°C) by default. To adjust the space 1. When an error higher than Level 2 occurs (the Boiler may heating water temperature: stop operation or only has basic functions), the Boiler enters <Error Display mode>...

  • Page 37: Adjusting The Dhw Temperature

    4.4.7 Adjusting the DHW Temperature NOTE WARNING The Outdoor Reset Control will take precedence over this ● temperature setting. Be carefully before adjusting the water temperature. Water In case of outdoor reset sensor malfunction, the boiler will ● above 120°F (52°C) can cause instant scalding, severe burns, or operate at this set temperature.

  • Page 38: 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 (°C) mode; ex) at 60°C (A) Space heating supply water Display of the current space heating temperature...
  • Page 39 Item Description Display In case of using water pressure sensor, turn-on of psi icon, indication of water pressure at segment. ex )12.3 psi (I) Space heating water pressure Display of current water pressure In case of DHW Priority time being set as 40 minutes. Indicating DHW priority use time (J) DHW Priority Time currently set (0 ~ 180min)

  • Page 40: Error Occurrence History Display

    4.4.9 Error occurrence history display NOTE 1. At the <Normal operation mode> or <Error display mode>, press the [Info] button for over 2 seconds to access the error While in <ERROR HISTORY DISPLAY MODE> the first digit ● history mode. indicates the history of the error with 0 being the most recent.

  • Page 41: Information Display (For Servicer)

    4.4.10 Information display (for servicer) 1. At the <Normal operation mode>, press the [Diagnostic] button once to access the service information display. 2. Press [+] or [-] to navigate through the user parameters. 3. Item of current SERVICE Information Data is indicated as an alphabetical numbering on the first segment and relevant DATA value is indicated at the 2 and 4 segment.
  • Page 42 Item Description Display If Finned Tube Baseboard is set; Display of heat load (1~7) 1: Finned Tube Baseboard 2: FAN Coil 3: Cast Iron Baseboard (G) Outdoor reset curve 4: Low Mass Radiant If Outdoor Reset is not used; 5: High Mass Radiant 6: Radiator 7: Custom (set by installer) If Boost interval time is set at 30 minutes;...
  • Page 43 Item Description Display Display of the APS value as voltage up to the first decimal place, ex) 3.2V; Display of current APS voltage (O) Current APS value Exhaust Gas Temperature display for Celsius (°C) mode with sensor, ex) 60°C Exhaust Gas Temperature display for Fahrenheit (°F) mode with sensor, ex) 120°F Display of current exhaust gas (P) Exhaust Gas Temperature...
  • Page 44 Item Description Display 0~2,000ft 2,000~5,400ft (S) Altitude setting Display of current altitude level information setting 5,400~7,700ft 7,700~10,100ft For Celsius (°C) mode; ex) at 60°C Display of the current system (V) Space heating system space heating outgoing water supply water temperature For Fahrenheit (°F) mode;...
  • Page 45 Item Description Display For Celsius (°C) mode; ex) at 30°C (Y) Temperature for exhaust Indicating current exhaust gas gas 2. 2 temperature. For Fahrenheit (°F) mode; ex) 100°F In case of CH Demand Off Indicating current heating (Z) CH Demand Demand.
  • Page 46 Item Description Display For Celsius (°C) mode; ex) at 60°C Indicating current DHW set (3) DHW set temperature. temperature. For Fahrenheit (°F) mode; ex) 120°F In case of Boiler Pump Off. Indicating current Boiler Pump (4) Boiler Pump status. In case of Boiler Pump On. In case of System Pump Off Indicating current System Pump (5) System Pump...
  • Page 47 Item Description Display In case of Dual Venturi Off. Indicating current Dual Venturi (8) Dual Venturi status. In case of Dual Venturi On. In case of LWCO Off. Indicating current LWCO input (9) LWCO status. In case of LWCO On. In case of Air Handler Output Off.

  • Page 48: Special Parameter Mode

    4.4.11 Special Parameter mode You can modify parameter settings for boiler operations, 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. Setting parameters improperly may lead to property damage or injury.

  • Page 49: Version 1.0 Nhb Service Manual

    (1) Parameter setting Mode 1. When [+] / [-] buttons are operated at <Special Parameter mode> and if 1 PAR item is indicated at the segment, at one time pressing of [Mode] button, then it is entered into <Password input mode>. 2.
  • 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 (°C) mode; ex) at - 10°C This mode is used to configure the heat load type to be used with the Outdoor Reset Control mode The boiler will operate at the high end of the supply or return set-point range at this outdoor temperature.
  • Page 52 Item Description Display This menu is used to configure the desired space heating capacity. When the MAX heat capacity for boiler operates in the Normal mode, the space heating capacity is limited to Space heating is 95% the set value (%) (F) Space Heating Max Heat Capacity Setting range...
  • Page 53 Item Description Display For Celsius (°C) mode; ex) at 2°C During space heating, the boiler turns off the burner when the space heating supply temperature meets or exceeds the burner-off temperature. (L) Space Heating Burner OFF Setting range Default For Fahrenheit (°F) mode; Differential ex) at 4°F 2 ~ 54°F(1 ~ 30°C)
  • Page 54 Item Description Display For Celsius (°C) mode; ex) at 65°C This menu may be used to make changes to the maximum return temperature range the Return Control mode is in use. When configuring the Custom mode in the Outdoor Reset Control mode, the return temperature (P) Return Absolute changes based on the return absolute MAX temperature range.
  • Page 55 Item Description Display In case of Boiler Pump Off Setting of Boiler Pump On / Off at DHW Mode (W) Setting of DHW Setting range Default Mode – Boiler In case of Boiler Pump On Pump ON / OFF In case of System Pump Off Setting of System Pump On / Off at DHW Mode (X) Setting of DHW Setting range...
  • Page 56 Item Description Display Displaying Space Heat Min Heat Capacity. Space heating min capacity is 12% Setting range Default (3) Space Heating Minimum heat Min Heat Capacity Space heating min capacity ~ [Space heating max performance capacity – 20%] available of model Displaying DHW Min Heat Capacity.
  • Page 57 (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 58 Component Test Performed Display Method The current APS value and the current RPM value are repeatedly displayed at intervals of 2 seconds. Gradually increase / decrease the speed of the fan motor starting from 0 RPM to full speed and back down to 0 RPM Whenever the [+], [-] button is pressed, the condition is toggled as On ->...
  • Page 59 (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 60: Resetting The Boiler (Factory Reset)

    4.4.12 Resetting the Boiler (Factory Reset) If an error message appears, you can try resetting the boiler to resolve the problem. To reset the boiler, press the Reset button. MODE If resetting the boiler does not solve the problem, refer to the Troubleshooting section of this manual or contact Technical Support at 1-800- 519-8794.

  • Page 61: Version Display

    4.5 Version Display Press the [Diagnostic] button for more than 10 seconds at <Power Off mode> will display the Main Controller firmware version for 3 seconds, display the Panel firmware version for 3 seconds and return the system to <Power Off mode>. Item Description Display...

  • Page 62: Ladder Diagram

    4.7 Ladder Diagram NHB Service Manual Version 1.0...

  • Page 63: Electrical Diagnostic Point & Wiring Diagram

    4.8 Electrical Diagnostic Point & Wiring Diagram Version 1.0 NHB Service Manual...
  • Page 64 Point Function CN No. Wire Color Normal Value Check CN13 Exhaust Thermistor BLUE-BLUE DC 0~5V Voltage changes according to temperature. Heating Return CN13 BLUE-BLUE DC 0~5V Voltage changes according to temperature. Temperature Sensor HEATING Supply CN13 BLUE-BLUE DC 0~5V Voltage changes according to temperature. Temperature Sensor High Temperature Limit CN13...

  • Page 65: Key Components Description

    4.9 Key Components Description 4.9.1 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 66: High Limit Switch

    4.9.2 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 67: Thermistor

    4.9.3 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 68: Fan Motor

    4.9.4 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 69: Flame Rod Assembly

    4.9.5 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 70: Ignition Transformer

    4.9.6 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 71: Aps

    4.9.7 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 72: 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. Failure Event Unable to open/close 1.

  • Page 73: 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 74: Primary Heat Exchanger

    4.9.10 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 75: Secondary Heat Exchanger

    4.9.11 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 76: Water Pressure Sensor

    4.9.12 Water Pressure Sensor Part Check Point Function Detects water pressure in the heating system. Failure Event Unable to detect or measure to change in water pressure. Effects Water filling system does not operate automatically Error Code E302, E352, E353 1.

  • Page 77: Dual Venturi

    4.9.13 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 1.

  • Page 78: 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 79: Error Code Classification

    5.2 Error code classification Error Code Sub Code Function 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 80 Error Code Sub Code Function Self-diagnostic / Action 1. Turn OFF the system for at least 30 minutes then restart. 2. Clean the inlet filter. Exhaust Overheat : exhaust limit switch shuts down the unit when the flue 3. Check exhaust thermistor and verify [P] value in E030 temperature exceeds 230 °F (110 °C) for more than DIAGNOSTIC mode...
  • Page 81 Error Code Sub Code Function Self-diagnostic / Action Abnormal operation: system return thermistor Check the thermistor. (open) E279 Abnormal operation: system return thermistor Check the thermistor. (short) Check if the supply water outlet piping of heating E291 Supply / Return inversion limit piping and return inlet piping are mutually changed.
  • Page 82 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 83: 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 84 Sudden increase of temperature due to PCB DIP S / W model setting error or max setting. DIP S / W No. Capacity Capacity setting 55,000 BTU (NHB-055) Other potential issues 80,000 BTU (NHB-080) 110,000 BTU (NHB-110) 150,000 BTU (NHB-150) Defective PCB If the trouble continues despite the checking of above items, replace the PCB.

  • Page 85: 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 86 Scenario2 Is gas valve operating Does the main gas valve Check connector normally? have proper voltage? Check the voltage between the WHITE-YELLOW of CN 16: 22-24 VDC Check the voltage between the WHITE-RED wires of CON 4: 22-24 VDC Check that gas valve is open or Is gas valve open? check LP supply In case of LP gas model, low gas pressure can cause...
  • Page 87 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 88 Failure mode Cause Check method Igniter Bracket 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 89 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 90 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 91: 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 92: 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 93 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 94 Fault Possible Causes Check method Model Gas Type Offset -0.04 in ± 0.01 in NHB-055 -0.03 in ± 0.01 in -0.04 in ± 0.01 in NHB-080 -0.02 in ± 0.01 in -0.04 in ± 0.01 in NHB-110 -0.02 in ± 0.01 in -0.04 in ±...
  • Page 95 Fault Possible Causes Check method [Location of assembly screw and ground bolt in heat exchanger] 1. Check the presence of debris in the metal fiber. Defected metal fiber 2. Check the sagging of the metal fiber and then the gaps with the electrode. [Gap between the electrode and metal fiber: 12mm] Flame loss will occur if the gas orifices in the Dual Venturi are clogged.

  • Page 96: 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 97 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 98: 030Error

    5.2.6 030Error Error occurrence conditions and check items Error Description If the temperature sensor on the top 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 99 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 100: 046Error

    5.2.7 046Error Error occurrence conditions and check items Is heat exchanger Check connector thermistor normally ( #7 and #8 of CN 13) operating? Is resistance within 1 step: Flushing, Clean Filter normal range? 2 step: Try to restart (refer to page 67) 3 step: Replace PCB Replace heat exchanger thermistor.

  • Page 101: 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 102 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 103: 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 104 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 105: 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 106 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 107: 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 108 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. Defective sensor Check the resistance of the temperature sensor. (Defective if it is 30kΩ or higher) Temperature sensor Replace the temperature sensor if the resistance value is abnormal.

  • Page 109: 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 110 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 111: 271Error

    5.2.14 271Error Error conditions and Check Items Error Description E271 If the temperature differential (supply temperature - return temperature) is higher than Temperature differential limit 54°F(30°C), the alarm code (E271) is displayed. The system operates normally. Check if flow rate heating pipe is proper? Check if the heating pipe is clogged with debris. Check if Air vent is close totally Check items Check if capacity of the circulation pump(external) is enough to circulate water in pipe...

  • Page 112: 278Error

    5.2.15 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 113: 279Error

    5.2.16 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 114: 291Error

    5.2.17 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 115: 302Error

    5.2.18 302Error Error conditions and Check Items Error Description E302 If the water pressure sensor senses low water level as the heating pipe pressure is low, the Low water system stops operation of the boiler and error (E302) is displayed on the front panel. 1.

  • Page 116: 352Error

    5.2.19 352Error Error conditions and Check Items Error Description Upon receiving a signal from the water pressure sensor, the system displays the error(E352) on E352 front panel. High water pressure High water level error if the water level of 56.6 psi or higher continues 3 seconds. Error is automatically cancelled if water level is 43.5 psi or lower.

  • Page 117: 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 118: 515Error

    5.2.21 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 119: 517Error

    5.2.22 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 5.2.23 594Error Error occurrence conditions and check items Error Description...

  • Page 120: 615Error

    5.2.24 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. 5.2.25 740Error Error conditions and Check Items Error...

  • Page 121: 777Error

    5.2.26 777Error Error conditions and Check Items Check the factory Is the factory jumper installed jumper Is the LWCO installed installed properly on and jumper properly? CN24? connection (CN24) Check the Is the output voltage Is proper power being connecting normal on CN25? supplied to the LWCO? terminals...

  • Page 122: 782Error

    5.2.27 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 Reconnect panel to the PCB 5.2.28 784Error Error occurrence conditions and check items 1.

  • Page 123: 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 124: 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 125: 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 126: 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 127: Fuse

    6.2.2 Fuse 5. Remove the Clip from the Strainer and the 3 screws from the Base. 1. Turn off the gas supply to the unit. 2. Disconnect the unit from the power supply. 3. Locate the fuse housing shown in Figure 3 below. Open the housing to expose the fuse.
  • Page 128 6. Disconnect wiring connectors of Fan and Venturi. 9. To detach the Fan from the Fan Ass’y and replace it with the new part. Figure 9 Figure 13 7. Remove the 2 screws from bracket of Gas Mix Pipe. 10. Remove the 5 screws from Intake Pipe and Venturi. Figure 10 Figure 14 8.

  • Page 129: Flame Rod

    6.2.4 Flame Rod 6.2.5 Ignition Transformer 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. Disconnect the unit from the power supply. 3.

  • Page 130: Aps

    6.2.6 APS 6.2.7 Main Gas Valve 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. Disconnect the unit from the power supply. 3.
  • Page 131 6. Remove the 2 screws located at the bottom of the unit that are 8. Replace the O-ring where the gas valve assembly attaches to attached to the gas valve. the elbow. Make sure the old O-ring is discarded. 9. Replace the old gas valve with the new part and reattach the elbow and gas pipe to the gas valve.

  • Page 132: Condensate Trap

    6.2.8 Condensate Trap 6.2.9 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 133: Components Diagram And Part List

    7. Components Diagram and Part List 7.1 Case Assembly Version 1.0 NHB Service Manual...
  • Page 134 Description Part # Remark 20030085A NHB-110 / 150 Case 20030088A NHB-055 / 080 Cover 30013463A 30013044A Front Panel 30013041A Exhaust Pipe Assembly 30008673A Intake Air Duct Assembly 30008662B Intake Air Fillter 20007667A Air Pressure Sensor 30010238A Rubber Ring 20029318A PCB Lower Bracket...

  • Page 135: Heat Exchanger And Waterway Assembly

    7.2 Heat Exchanger and Waterway Assembly Version 1.0 NHB Service Manual...
  • Page 136 Description Part # Remark 30013575A NHB-110 / 150 Heat Exchanger Assembly 30014060A NHB-055 / 080 O-Ring (P29) 20017923A NHB-110 / 150 O-Ring (Φ17.5x2.7t) 20006947A NHB-055 / 080 20017724A NHB-110 / 150 Fastener 20007853A NHB-055 / 080 High Limit Switch 30002558A...
  • Page 137 Description Part # Remark 20030133A NHB-110 / 150 Air Vent Adapter 20031488A NHB-055 / 080 20030136A NHB-110 / 150 Return / Supply Adapter 20030466A NHB-055 / 080 Syphon 30014024A 20030135A NHB-110 / 150 H-Ex Connection Adapter 1 20026917A NHB-055 / 080...

  • Page 138: Combustion Parts Assembly

    7.3 Combustion Parts Assembly 10-1 10-2 10-3 NHB Service Manual Version 1.0...
  • Page 139 30013458A NHB-110 / 150 Mixed Guide Pipe 30013458A NHB-055 / 080 Fan Bracket 20030471A 30013985A NHB-150 10-1 Fan Assembly 30013984A NHB-055 / 080 / 110 30013981A NHB-150 10-2 Dual Venturi 30013982A NHB-110 30013983A NHB-055 / 080 20031242A NHB-150 10-3 Intake Pipe...
  • Page 140 Description Part # Remark Orifice Packing 20022660A 20032404A NHB-150 (NG) 20032403A NHB-110 (NG) 20032402A NHB-055 / 080 (NG) Gas Orifice 20032407A NHB-150 (LP) 20032406A NHB-110 (LP) 20032405A NHB-055 / 080 (LP) O-Ring (P34) 20019090A 30013955A NHB-150 Gas Pipe 30013509A NHB-110...

  • 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 maintenance recommended that the boiler is serviced annually. Check boiler area ● Daily Check pressure / temperature gauge ●...
  • Page 142 Memo NHB Service Manual Version 1.0...
  • Page 143 Memo Version 1.0 NHB Service Manual...
  • Page 144 Memo NHB Service Manual Version 1.0...
  • Page 145 Memo Version 1.0 NHB Service Manual...
  • Page 146 Memo NHB Service Manual Version 1.0...
  • Page 147 Service Manual NHB 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:

Nhb-080Nhb-110Nhb-150

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