Navien NHB-055 Service Manual Download Page 68

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68 NHB Service Manual

Version 1.0

4.9.4 Fan Motor

Part

Check Point

Function

Provides combustion air into the burner and purges exhaust flue gas.

Maintains the gas input with a long vent run, the fan operates with APS for ideal combustion.

Failure Event

1.  Fan speed failure: the fan RPM is around 0 RPM.
2.  The fan assembly screw is loose and/or the fan is disassembled.
3.  Disconnected or defective fan connection terminal assembly.

Effects

1.  Unstable combustion condition.
2.  Unit vibrating and noise.
3.  The boiler is not operating properly.

Error Code

E109, E110

Diagnostic

1. Visual inspection: check the fan connection wire and/or the fan mounting location.
2. Voltage check: Check range of voltage shown below.

Color / Number of wires

●

Black-Red: DC 127 V ~ 184 V

●

Black-Yellow: DC 15 V

●

Black-Orange: DC 0 ~ 7.5 V

●

Black-White: 0 ~ 6,700 RPM

Summary of Contents for NHB-055

Page 1: ...ppliance 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...

Page 2: ...2 NHB Service Manual Version 1 0 Version Description of changes Date 1 00 First Issue March 26 2015 1 0 Reviewed BY Paek Ji Ho Revisions...

Page 3: ...ation For Homeowner 38 4 4 9 Error occurrence history display 40 4 4 10 Information display for servicer 41 4 4 11 Special Parameter mode 48 4 4 12 Resetting the Boiler Factory Reset 60 4 5 Version Di...

Page 4: ...116 5 2 20 353Error 117 5 2 21 515Error 118 5 2 22 517Error 119 5 2 23 594Error 119 5 2 24 615Error 120 5 2 25 740Error 120 5 2 26 777Error 121 5 2 27 782Error 122 5 2 28 784Error 122 5 3 Troubleshoo...

Page 5: ...er to secure the services of qualified licensed professionals for the installation of hard wired carbon monoxide detectors a In the event that the side wall horizontally vented gas fueled equipment is...

Page 6: ...any other components parts or specifications Improper conversion from natural gas to LP gas or LP gas to natural gas or attempt to operate with a type of gas not specified for the boiler Any damage ma...

Page 7: ...itudes higher than4 500 ft please contact Navien Cet appareil est certifi pour une utilisation des altitudes de 0 4 500 pieds 1 370 m conform ment aux toutes les proc dures d installation haute altitu...

Page 8: ...5 NHB 080 NHB 110 and NHB 150 NG Natural Gas LP Propane Gas AP Air Pressure APS Air Pressure Sensor DHW Domestic Hot Water FM Fan Motor GPM Gallons Per Minute MGV Main Gas Valve RPM Revolutions Per Mi...

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

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

Page 11: ...ou feel something is wrong with the unit DO NOT allow children to operate or otherwise handle the unit WARNING GASTYPE and ACVOLTAGE This boiler is configured for Natural Gas from the factory If conve...

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

Page 13: ...l is divided into four types 055 080 110 and 150 Model Maximum Space Heating Input NHB 055 55 000 Btu h NHB 080 80 000 Btu h NHB 110 110 000 Btu h NHB 150 150 000 Btu h A separate heating expansion ve...

Page 14: ...owing diagram shows the key components of the boiler Component assembly diagrams and particular parts lists are included in the Appendixes Intake Air Air Filter Front Panel PCB Power Switch APS LWCO F...

Page 15: ...rsion 1 0 Metal fiber Premix Buener Mixing Gas Guide Fan Motor Dual Venturi Condensate Trap Ignition Teansformer Igniter Flame Rod Primary Heat Exchanger Secondary Heat Exchanger Gas Valve Gas Connect...

Page 16: ...ing Water3 MBH AFUE2 Water Pressure Water Connection Size Supply Return Min Max NHB 055 8 55 51 44 95 12 30 psi 1 in NPT NHB 080 8 80 74 64 95 NHB 110 10 110 102 89 95 NHB 150 10 150 138 120 95 1 Rati...

Page 17: ...Secondary Stainless Steel Venting Exhaust 2 in or 3 in PVC CPVC approved polypropylene 2 in or 3 in Special Gas Vent Type BH Class III A B C Intake 2 in or 3 in PVC CPVC polypropylene 2 in or 3 in Spe...

Page 18: ...ter A Air Intake 2 in B Exhaust Gas Vent 2 in C Air Vent Connection 3 4 in D Rubber Grommet 1 in E Space Heating Return 1 in F Condensate Outlet 1 2 in G Gas Connection 3 4 in H Space Heating Supply 1...

Page 19: ...age MAX 1 ON 2 ON 4 1 Setting the DIP Switches CAUTION Do not remove the front cover unless the power to the boiler is turned off or disconnected Failure to do so may result in electric shock The boil...

Page 20: ...t to On ensure that CPVC piping is used for exhaust venting 4 1 2 Front Panel DIP Switches Set of Front Panel DIP Switch 1 10 switch unit The DIP SW 1 on the front panel configures the temperature uni...

Page 21: ...ng is not applied In order to change DIP SW setting be sure to apply the power of controller in the state that normal communication with panel is possible 4 2 Measuring the Inlet Gas Pressure WARNING...

Page 22: ...rged 8 Leave the boiler on until the boiler shuts down due to lack of gas supply and then turn off the boiler 9 Remove the front cover by loosening the 4 Phillips head screws securing it to the case 1...

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

Page 24: ...570 2 370 2 200 2 070 1 950 1 730 1 570 1 440 The inlet gas pressure must be maintained between 3 5 in and 10 5 in WC for natural gas and between 8 0 in and 13 5 in WC for liquefied propane The appli...

Page 25: ...s who is experienced in such work familiar with all precautions required and has complied with all of the requirements of the authority having jurisdiction In Canada The conversion shall be carried ou...

Page 26: ...at location A the connection below the gas valve where it connects to the pipe See Figure 5 for reference Once the screws are removed carefully separate the pipe from the gas valve 10 Once the gas in...

Page 27: ...LY O ring O ring Gas Orifice Figure 7 Exploded view of Gas assembly DANGER See Figure 7 Inspect the O ring between the gas valve and gas valve inlet adapter whenever they are disassembled The O ringmu...

Page 28: ...ccording to the supply gas type Failure to properly set the DIP switches could cause carbon monoxide poisoning resulting in severe personal injury or death 17 Turn on the gas and water supply to the b...

Page 29: ...2 stage D MAX mode refer to 3 Operation Conditions Settings on page 59 Measure the CO2 value at high fire If the CO2 values do not match Table 2 at high fire do not adjust the gas valve Check for the...

Page 30: ...jury death or substantial property damage 19 Once the CO2 or offset values have been confirmed apply the included conversion stickers to show that the appliance has been converted to propane gas Place...

Page 31: ...rol mode status Supply water Control R Displays the Return Water Control mode status Return Water Control Displays the data set in each Segment according to display status Segment Displays the Combust...

Page 32: ...de Plus Minus Short Key Function Remarks Diagnostic short key Display of information for service Mode short key Sets heating temperature Sets hot water temperature Displays confirms information for cu...

Page 33: ...lay Possible only with power turned OFF Diagnostic Plus Reset Power long key 5Seconds Factory reset Possible only with power turned OFF All button LEDs will be turned on to their maximum when buttons...

Page 34: ...laying the water temperature of the space heating supply the supply or return water icon flashes depending on the space heating control mode 4 4 4 Normal Operation 1 Enter Normal Operating mode by pre...

Page 35: ...pressure is 12 3psi the image below repeats at 5 seconds intervals Celsius specification Flashing 5 sec psi Item Description Display 2 Level1 Error occurs Level 1 Error occurrence status When the cur...

Page 36: ...l be released after RST displays for 3 seconds if the Boiler meets the conditions to release the error If releasing the error is not possible the error code will display again after 3 seconds 7 When r...

Page 37: ...your settings during a power outage 4 4 7 Adjusting the DHWTemperature WARNING Be carefully before adjusting the water temperature Water above 120 F 52 C can cause instant scalding severe burns or dea...

Page 38: ...ing water temperature For Celsius C mode ex at 60 C For Fahrenheit F mode ex 120 F F Outdoor air temperature with optional Outdoor Temperature Sensor only Display of current outdoor temperature Outdoo...

Page 39: ...time currently set 0 180min In case of DHW Priority time being set as 40 minutes Pri K System Supply Temperature Indicating current system supply water temperature In case of Celsius C temperature mod...

Page 40: ...ISPLAY MODE displays CLR and deletes all the ERROR HISTORY DATA 5 Press the Reset button once to return to the Normal operation mode 6 If there is no button input for 5 minutes then the system automat...

Page 41: ...er pressure psi 5 Press the Reset button once to return to the Normal operation mode 6 If there is no button input for 1 hour then the system automatically returns to the Normal operation mode Item De...

Page 42: ...sure Display of current water pressure Using sensor in psi ex 12 3 psi psi J Heat Capacity Display of current heat capacity range 0 100 Heat capacity display in percentage ex 100 K Flame State Display...

Page 43: ...C mode with sensor ex 60 C Exhaust Gas Temperature display for Fahrenheit F mode with sensor ex 120 F Exhaust Gas Temperature display without sensor Q Model and Capacity Display of currently set mode...

Page 44: ...r temperature Display of the current system space heating outgoing water temperature For Celsius C mode ex at 60 C For Fahrenheit F mode ex 120 F W Space heating system return water temperature Displa...

Page 45: ...at 30 C For Fahrenheit F mode ex 100 F Z CH Demand Indicating current heating Demand In case of CH Demand Off In case of DHW Demand On 1 DHW Demand Indicating current DHW Demand In case of DHW Demand...

Page 46: ...urrent Boiler Pump status In case of Boiler Pump Off In case of Boiler Pump On 5 System Pump Indicating current System Pump status In case of System Pump Off In case of System Pump On 6 DHW Pump Indic...

Page 47: ...i On 9 LWCO Indicating current LWCO input status In case of LWCO Off In case of LWCO On Air Handler Output Indicating current Air Handler Interface output status In case of Air Handler Output Off In c...

Page 48: ...he Diagnostic button for 5 seconds to enter the Special Parameter mode 2 Press the or buttons at Special Parameter Mode refer to the table below 3 Press the MODE Button once enters boiler to the curre...

Page 49: ...henever buttons are pressed it changes Parameter values 9 If Mode button is pressed or button is not pressed for 10 seconds a finally set value is applied Parameter change mode is terminated and it re...

Page 50: ...Display A Outdoor Reset Control Mode This mode is used to configure the Outdoor Reset Control mode This mode is enabled by default from the factory Outdoor Reset in us Outdoor Reset not in use B Outdo...

Page 51: ...e at the high end of the supply or return set point range at this outdoor temperature Outdoor Low Temperature Setting Range Setting range Default Outdoor Low Temperature Set point 9 F 5 C 104 F 40 C 7...

Page 52: ...turn temperatures reach the set values for boiler operation stop temperatures The boiler will not resume space heating until the duration elapses even when the space heating supply or return temperatu...

Page 53: ...This menu may be used to make changes to the maximum supply temperature range when the Supply Control mode is in use When configuring the Custom mode in the Outdoor Reset Control mode the supply temp...

Page 54: ...mode in the Outdoor Reset Control mode the return temperature changes based on the return absolute MIN temperature range Setting range Default 68 F 20 C MAX Set point 18 F 10 C 86 F 30 C For Celsius C...

Page 55: ...ode during heating in case of simultaneous request of heating and warm water Setting range Default ON OFF OFF In case of DHW Pump Off In case of DHW Pump On Z Setting of heat exchanger protection leve...

Page 56: ...e display again press the mode button If entering Parameter Initializing mode press button or Password Change mode This menu may be used to set a new password to access the parameter setting menu To s...

Page 57: ...fter completion of performance 6 The operation of boiler pump system pump warm water pump Dual Venturi functions is tested by an On Off manual operation with buttons and if Reset button is pressed or...

Page 58: ...ons are pressed the status changes to On Off or Off On Whenever the button is pressed the condition is toggled as On Off or Off On Hot Water Pump In entering Test it becomes Pump On status and wheneve...

Page 59: ...1st Stage MAX g CH 2nd Stage MAX a NORMAL Operation condition 3 If the Reset button is pressed once then it returns to the Special Parameter mode Displayed as the previously entered item 3 OPR 4 If t...

Page 60: ...ower Off mode for more than 5 seconds will initialize the system to its factory reset and the system will convert its mode to Normal Operating mode after displaying INIT on Segments for 5 seconds 2 Re...

Page 61: ...Error Code Conditions a Panel Communication Error E782 Level 1 Automatically releases the error code when the main controller doesn t answer for 60 seconds but the system operates normal communication...

Page 62: ...62 NHB Service Manual Version 1 0 4 7 Ladder Diagram...

Page 63: ...Power Code W Fuse 10A GY Ground CON1 BK BK Front Panel BK BKBK BKBK BKBK BKBK BK CN13 B B Exhaust 1 Thermistor B B B B Return Thermistor B B B B Supply Thermistor B B BK BK High Limit S W CN1 CN26 CN1...

Page 64: ...e APS operation F Flame Rod CN19 1 BLACK DC 10uA Measure the current when the burner is operating Ground Wire CN19 2 GREEN YELLOW Check for properly grounded wire G Gas Valve CN16 1 2 WHITE YELLOW DC...

Page 65: ...re Event Malfunctioning PCB Effects A component may not operate within the unit and could produce an error code In most cases of PCB failure the whole unit will not operate until the problem is resolv...

Page 66: ...han 230 F or 110 C in heat exchanger will activate the high limit switch Failure Event Unable to detect excessively high water temperature if switch fails Effects Unable to shut down the boiler if the...

Page 67: ...9 Diagnostic 1 Visual inspection Check wire connections are secure 2 Check the resistance of the sensor Stop operating and lower the temperature before checking Testing inspection information Resistan...

Page 68: ...n assembly screw is loose and or the fan is disassembled 3 Disconnected or defective fan connection terminal assembly Effects 1 Unstable combustion condition 2 Unit vibrating and noise 3 The boiler is...

Page 69: ...the ignition process 2 Produces multiple unsuccessful attempts to ignite Effects 1 The unit cannot ignite during the ignition process and E003 or E004 error codes will display 2 Durability of the igni...

Page 70: ...uccessful attempts to ignite Effects 1 The unit cannot ignite during the ignition process and E003 or E004 error codes will display 2 Durability of the igniter wears down Error Code E003 E004 Diagnost...

Page 71: ...Effects 1 The boiler is not operating 2 Produces excessive carbon monoxide emissions Error Code E110 Diagnostic 1 Visual inspection Check wire connections are secure 2 Voltage check Check range of vo...

Page 72: ...ure Event Unable to open close Effects 1 No flames 2 No operation of the unit Error Code E003 E012 Diagnostic 1 Visual inspection Check wire connections are secure 2 Check if the solenoid valve of Mai...

Page 73: ...1 Unable to initialize sustain combustion 2 Dust or soot deposit on the burner surface 3 Possible gas leakage from burners Effects 1 Abnormal combustion 2 Unstable flame conditions and or flame loss 3...

Page 74: ...t loss Failure Event 1 Water and or exhaust gas leakage through a crack 2 Improper heat transfer can cause the water in the heat exchanger to boil due to possible scale formation Effects 1 Exhaust gas...

Page 75: ...ustion chamber which minimizes heat loss Failure Event 1 Water and or exhaust gas leakage through a crack 2 Improper heat transfer can cause the water in heat exchanger to boil Effects 1 Exhaust gas l...

Page 76: ...ure Effects Water filling system does not operate automatically Error Code E302 E352 E353 Diagnostic 1 Visual inspection check the circulation pump connection wire 2 Voltage check Check range of volta...

Page 77: ...to control the amount of mixed gas by stage 1 and 2 Failure Event 1 Blade not closing 2 Blade not opening Effects 1 Frequent On Off due to excessive heat 2 Fail to reach the set temperature due to la...

Page 78: ...ockage Manual RESET Abnormal APS open short initial value or no answer No error display CH System E205 2 Abnormal H E outlet thermistor open or short Auto RESET E218 1 Abnormal H E inlet thermistor op...

Page 79: ...ground connection screws on heat exchanger E004 0 False flame detection 1 Ensure ground wire is connected 2 Check the igniter for spark E012 0 Flame loss 1 Check the main gas line Is the valve open 2...

Page 80: ...uri Limit Switch operation Close OFF 3 Abnormal Dual Venturi Limit Switch operation Open ON E109 0 Abnormal fan motor activity 1 Check and clean the intake air filter 2 Check and clean the fan motor 3...

Page 81: ...he PCB connection 2 Check the Igniter 9 Abnormal communication between PCB and FAN 1 Check the PCB connection 2 Check the Fan 10 Abnormal monitoring device of PCB 1 Check the PCB connection 11 12 Abno...

Page 82: ...peration zone controller communication external device 1 Check the zone controller wiring connection 2 Check the zone controller PCB 3 Check the Main and Panel PCB If any of the above solutions do not...

Page 83: ...ernal operating status Run Pump Test Mode 2 Check if filter strainer of the heating pipe is clogged 3 Check if the main heat exchanger is clogged 4 Check the heating inlet outlet valve and distributio...

Page 84: ...ed Aluminium distributor oxidized steel etc The main heat exchanger is clogged Separate the inlet outlet pipe from the main heat exchanger and blow air through the heat exchanger to check if the pipe...

Page 85: ...Check the flame rod wiring and grounding 6 Check if the air pressure hose is broken or clogged 7 Check if the air pressure sensor works properly 8 Check the PCB DIP switch settings 9 Adjust the offset...

Page 86: ...TE RED wires of CON 4 22 24 VDC In case of LP gas model low gas pressure can cause Ignition Failure Normal gas pressure 8 0 13 5 w c Yes No No No Yes Yes Scenario3 Is the flame detection device normal...

Page 87: ...bustion 2nd stage MAX combustion setting DIP S W 1 1 ON 5 If a CSST connector has been used check to ensure that it is not been over tightened resulting in the seal obstructing gas flow 6 Check the me...

Page 88: ...gap if there is a discharge of electricity from the metallic part of the burner Ensure that the insulating gasket is installed between the electrode and burner casing Check the input power to the ign...

Page 89: ...en 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 3 If power supply is normal check if the coil is open Check the resistance...

Page 90: ...ng good contact with the case Or use a multi meter to measure the flame sensing current normally over 3 4 A Measuring flame current Grounding wire position Flame loss and noise occurs at ignition Chec...

Page 91: ...nge 4 Check the PCB and replace if defective Is the flame detected in the burner when there is no ignition External noise current Clean or replace flame rod Check the current 1 of CN 19 Over 3 4 A See...

Page 92: ...ually cleared on the front panel Check items 1 Measure with a manometer the gas supply pressure NG 3 5 10 5 W C LP 8 13 5 W C 2 Check the Gas meter Capacity 3 Tighten the ground connection screws on h...

Page 93: ...seal obstructing gas flow 6 Check the gas meter capacity Example Gas meter Boiler Furnace Domestic gas stove 425 CFH Gas Meter 195 CFH Boiler 58 8 CFH Furnace 63 7 CFH Domestic gas stove CFH 1 020 Bt...

Page 94: ...the fire detecting electrode Cause Due to the properties of the electrode the oxide film is created due to long term exposure to the high temperature therefore errors may be caused in detecting the f...

Page 95: ...er and then the gaps with the electrode Gap between the electrode and metal fiber 12mm Flame loss during 2nd stage Blockage in the gas orifice plate Flame loss will occur if the gas orifices in the Du...

Page 96: ...ntroller is working properly Check resistance value or continuity refer to page 66 2 Check the hot water temperature sensor refer to page 76 3 Check for proper power supply 120 VAC to the pump externa...

Page 97: ...defective sensor check if the deviation of temperature is large due to a defective temperature sensor Check the output temperature displayed on the front panel 2 Measure the temperature sensor resista...

Page 98: ...30 F 110 C for 10 minutes or over E030 error code will display and perform post purge Automatically cleared 2 When the controller detects the exceeding temperature of 140 F 60 C while performing post...

Page 99: ...xchanger if it is damaged or cannot be unclogged Defective part Defective temperature sensor Defective contact point of the exhaust gas overheat controller 230 F 110 C Max Check connection of the over...

Page 100: ...hanger thermistor Check connector 7 and 8 of CN 13 1 step Flushing Clean Filter 2 step Try to restart 3 step Replace PCB Yes Yes No No 5 2 8 047Error Error occurrence conditions and check items Is exh...

Page 101: ...Dual Venturi is operating correctly Run the Dual Venturi Test Mode 2 Check that the wiring harness is connected correctly and the cables are not damaged Is Dual venturi closed Is Dual venturi repeated...

Page 102: ...3 Wait until Fan Auto Adjusting is complete 4 Enter the Dual Venturi Test Mode and perform a test 1 Repeat the test at least twice Turning the unit ON and OFF once makes one test cycle ON OFF ON OFF...

Page 103: ...sor should be normal Check items 1 Check if the fan motor works normally using the component test mode refer to page 57 2 Check the power supply to the fan Black Red approx DC 127 184 V 3 If RPM is si...

Page 104: ...operating and the power supply is normal Follow the instructions listed below and replace the fan 1 Unplug the power cable to the unit and then wait for 10 seconds until the remaining SMPS voltage co...

Page 105: ...gged 2 Check if the condensation drain line or the drain is clogged 3 Check the flue and exhaust to verify proper installation and clearances Circulation of exhaust gas generates noise 4 Check if the...

Page 106: ...r clogged 2 Replace the old PCB with the latest version Condensate drain error Condensate drain error Exhaust air is blocked due to condensate drain error Check if the condensate hose or the siphon is...

Page 107: ...uding leakage 2 Replace the defected heat exchanger output temperature sensor 3 Check circulation pump external type operating status and for proper flow through the space heating line 4 Check the vol...

Page 108: ...ture sensor Defective if it is 30k or higher Replace the temperature sensor if the resistance value is abnormal Check the temperature displayed on the front panel Possible Issues Defective circulation...

Page 109: ...itiates shutdown Check items 1 Check if the heat exchanger input temperature sensor connector is wet due to any reason including leakage 2 Replace the defected heat exchanger input temperature sensor...

Page 110: ...the resistance of the temperature sensor Defective if it is 30k or higher Replace the temperature sensor if the resistance value is abnormal refer to page 67 Check the temperature displayed on the fr...

Page 111: ...culate water in pipe Check if Air Purge is fully done in the system If Air Vent is opened Is the space heating pipe connection normal Check the supply and return temperature sensor Replace space heati...

Page 112: ...persists replace the pump Is the system supply temperature sensor normal Check connector 7 and 8 of CN 13 Replace system supply thermistor Resistance between 7 and 8 of CN13 is from 0 437k to 176k at...

Page 113: ...ssue persists replace the pump Is the system return temperature sensor normal Check connector 5 and 6 of CN13 Replace system return thermistor Resistance between 5 and 6 of CN13 is from 0 437k to 176k...

Page 114: ...connection is inversed 2 Check the supply temperature sensor connection 3 Check the return temperature sensor connection Is the space heating pipe connection normal Check the supply and return temper...

Page 115: ...pipe 2 Check if the water supplied pipe open 3 Check the water pressure sensor Leaking in unit Is the cold water valve open 1 Check cold water pressure 2 Check the water pressure sensor Check leaking...

Page 116: ...sure sensor is wet due to any reason including leakage 2 Check the controller Leaking in unit Is the water pressure sensor normal 1 Check connecter 1 2 and 3 of CN 22 Check leaking in unit Replace the...

Page 117: ...eck if the cold water pipe input water pressure sensor is wet due to any reason including leakage 2 Replace the water pressure sensor 3 Check the controller Leaking in unit Is the water pressure senso...

Page 118: ...page 72 Check the Fan voltage See page 63 64 forWiring Diagram 1 Check the wire connection between dual venturi and Main controller 2 Check the dual venturi 1 Turn off and on the Power RESET switch 2...

Page 119: ...onditions and check items Error Description E594 error If the communication is abnormal in parts of PCB the system displays E594 on the PCB Check items Check the PCB Error occurrence conditions and ch...

Page 120: ...normal outdoor sensor If an error under 2 2k or over 122 2k in the outdoor sensor is detected continuously for 3 seconds The system displays the error message E740 on the front panel If this occurs th...

Page 121: ...r power being supplied to the LWCO Replace the main PCB Check LWCO Check the factory installed jumper and jumper connection CN24 Check the connecting terminals CN25 No No Yes No Yes Yes Yes Check meth...

Page 122: ...to the PCB 1 step Reset the unit 2 step If problem persists replace the PCB and Front Yes NO 5 2 28 784Error Error occurrence conditions and check items Is the wiring from the front panel properly co...

Page 123: ...below the standard 2 Gas supply error due to defective air pressure sensor 3 If the same error is repeated it is due to a defective PCB Noise during combustion Boiling noise How to check boiling Boil...

Page 124: ...panel Water mixed with cold water The temperature of hot water at the tap is low while the temperature is high at the hot water outlet Cold water and hot water are mixed due to improper pipe installa...

Page 125: ...valve Check if the wire is fixed and properly attached on the main side of the heat exchanger Normal assembly Short circuit due to defective assembly Wiring near the heat exchanger Circuit breaker op...

Page 126: ...es 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...

Page 127: ...fuse is of an equivalent rating and that it is properly fixed inside the housing 6 Close the fuse housing 7 Turn on water supply power supply and gas supply to the unit 6 2 3 Fan Combustion Air 1 Turn...

Page 128: ...tach the Fan from the Fan Ass y and replace it with the new part Figure 13 10 Remove the 5 screws from Intake Pipe and Venturi Figure 14 Figure 15 11 Replace Fan Ass y to the original position and rec...

Page 129: ...w factory gaskets included with the flame rod when replacing the part onto the burner assembly 6 2 5 IgnitionTransformer 1 Turn off the gas supply to the unit 2 Disconnect the unit from the power supp...

Page 130: ...panel back onto the unit and secure it using the 4 screws 12 Turn on water supply power supply and gas supply to the unit NOTE Confirm that the new air pressure sensor is in the proper position before...

Page 131: ...to the gas valve 10 Reconnect the gas valve assembly to the unit by using the 4 screws at the elbow and 2 screws at the gas pipe 11 Reattach the gas valve wiring connector WARNING Failure to correctly...

Page 132: ...densate trap 10 Reattach the condensation trap to the unit and secure it using the 5 screws 11 Replace the controller to its original position 12 Turn on the water supply power supply and gas supply t...

Page 133: ...NHB Service Manual 133 Version 1 0 7 1 Case Assembly 10 1 3 4 2 8 7 9 9 5 6 9 10 1 3 4 2 8 7 9 9 5 6 9 7 Components Diagram and Part List...

Page 134: ...B 110 150 20030088A NHB 055 080 2 Cover 30013463A 3 PCB 30013044A 4 Front Panel 30013041A 5 Exhaust Pipe Assembly 30008673A 6 Intake Air Duct Assembly 30008662B 7 Intake Air Fillter 20007667A 8 Air Pr...

Page 135: ...NHB Service Manual 135 Version 1 0 7 2 Heat Exchanger and Waterway Assembly 13 12 11 7 7 2 5 4 14 16 6 19 7 3 3 18 3 21 6 2 22 1 9 14 15 12 10 12 12 12 7 7 20 12 7 12 2 19 17 12 12 8 7...

Page 136: ...002558A 5 SC Outlet Adapter 30014032A NHB 110 150 30014067A NHB 055 080 6 Thermistor 30012907A 7 Fastener 20030608A NHB 110 150 20017726A NHB 055 080 8 Return Pipe 30013501A NHB 110 150 30013502A NHB...

Page 137: ...080 15 Syphon 30014024A 16 H Ex Connection Adapter 1 20030135A NHB 110 150 20026917A NHB 055 080 17 Return Adapter 30014055A NHB 110 150 30014065A NHB 055 080 18 Igniter 30012226A 19 LWCO Pressure Se...

Page 138: ...138 NHB Service Manual Version 1 0 7 3 Combustion Parts Assembly 1 2 3 4 5 16 15 15 18 17 10 3 10 2 19 11 15 12 13 7 6 7 8 9 10 1 14...

Page 139: ...110 150 30011854A NHB 055 080 5 Burner Packing 20021677A NHB 110 150 20027105A NHB 055 080 6 Fan Damper 30008825A 7 Fan Packing 20022744A 8 Mixed Guide Pipe 30013458A NHB 110 150 30013458A NHB 055 080...

Page 140: ...A NHB 110 NG 20032402A NHB 055 080 NG 20032407A NHB 150 LP 20032406A NHB 110 LP 20032405A NHB 055 080 LP 13 O Ring P34 20019090A 14 Gas Pipe 30013955A NHB 150 30013509A NHB 110 30013510A NHB 055 080 1...

Page 141: ...e Return Filter YES NO Checking the Intake Air Filter YES NO Flushing the Heat Exchanger YES NO Replacement of Parts YES NO 8 3 Maintenance Schedules Owner maintenance Daily Check boiler area Check pr...

Page 142: ...142 NHB Service Manual Version 1 0 Memo...

Page 143: ...NHB Service Manual 143 Version 1 0 Memo...

Page 144: ...144 NHB Service Manual Version 1 0 Memo...

Page 145: ...NHB Service Manual 145 Version 1 0 Memo...

Page 146: ...146 NHB Service Manual Version 1 0 Memo...

Page 147: ...r Contact a licensed professional for the affected system for example a plumber or electrician When you contact Technical Support please have the following information at hand Model number Serial numb...

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