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Navien NCB-180 Service Manual

Manual is about: Condensing Boiler

Summary of NCB-180

  • Page 1

    Condensing boiler service manual 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.Navienamerica.Com. For warranty service, always contact technical support first.. ● contact the technic...

  • Page 2: Ncb-180/ 210/ 240

    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. Warn...

  • Page 4: Revisions

    Revisions version description of changes date 1.00 first issue october/27/2013 1.00 reviewed by:.

  • Page 5: Contents

    2 ncb service manual version 1.0 contents 1. Safety information 8 1.1 safety definitions 8 1.2 safety symbols 8 1.3 symbols used in the instructions 8 1.4 safety precautions 8 2. Product information 12 2.1 product information 12 2.2 components 14 3. Technical data 16 3.1 general specifications 16 3....

  • Page 6

    6. Replacement of parts 121 6.1 replacement procedure 121 6.2 components replacement instructions 121 6.2.1 pcb 121 6.2.2 fuse 122 6.2.3 fan motor (combustion air) 122 6.2.4 flame rod 123 6.2.5 ignition transformer 124 6.2.6 aps 124 6.2.7 main gas valve 125 6.2.8 condensate trap 126 6.2.9 flow senso...

  • Page 7

    4 ncb service manual version 1.0 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...

  • Page 8: Navien Warranty

    Navien warranty warranty period navien products come with a limited warranty covering labor, parts and the heat exchanger. The following warranty periods begin to run from the date of original installation. The date of original installation must be provided to navien, and upon request, proof of the ...

  • Page 9

    6 ncb service manual version 1.0 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...

  • Page 10

    Abbreviations and definitions abbreviation definition ncb general name of ncb-180, ncb-210, and ncb-240 ng natural gas lp propane gas ap air pressure aps air pressure sensor dhw domestic hot water fm fan motor garc gas air ratio control gpm gallons per minute mgv main gas valve rpm revolutions per m...

  • Page 11: 1. Safety Information

    8 ncb service manual version 1.0 1. Safety information 1.1 safety definitions the following safety symbols are used in this manual. Read and follow all safety instructions in this manual precisely to avoid unsafe operating conditions, fire, explosion, property damage, personal injury, or death. 1.2 ...

  • Page 12

    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...

  • Page 13

    10 ncb service manual version 1.0 danger installation requirements installation conditions may affect how the boiler is serviced. Read all related information in the “installation manual”. The boilers must be installed according to all local and state codes or, in the absence of local and state code...

  • Page 14

    Warning shut off the gas supply if the boiler is damaged. Have your installer or plumber show you the location of the gas shut off valve and demonstrate how to close the valve. If the boiler is damaged as a result of overheating, fire, flood, or any other reason, close the manual shut off valve and ...

  • Page 15: 2. Product Information

    12 ncb service manual version 1.0 this boiler has been approved for use in the usa and canada only. Using the boiler in any other country will void the manufacturer’s warranty. Should overheating occur or the gas supply fail to shut off, turn off the manual gas valve to the appliance. Do not use thi...

  • Page 17

    14 ncb service manual version 1.0 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 air filter mixing chamber front panel pcb exhaust flue duct ignitor & flame rod condensate ...

  • Page 18

    High limit switch fan & motor dual venturi air pipe gas pipe premix burner ignition transformer primary heat exchanger secondary heat exchanger pressure sensor (lwco) dhw heat exchanger gas valve dhw inlet filter (with built-in flow restrictor) dhw inlet dhw outlet flow sensor aps air vent circulati...

  • Page 19: 3. Technical Data

    16 ncb service manual version 1.0 3. Technical data 3.1 general specifications the following table lists the specifications for the boiler. Additional specifications about water, gas, electric, and air supplies (venting) appear in the installation section. Space heating specifications 1. Ratings are...

  • Page 20

    General specifications note this unit may be installed at elevations up to 10,100 ft (3,078 m) for use with natural gas, and up to 4,500 ft (1,370 m) for use with propane. 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) in...

  • Page 21

    18 ncb service manual version 1.0 3.2 dimensions the following diagrams show the dimensions of the boiler and the table lists the supply connections. Overhead view supply connections supply connections description diameter a air intake 2 in b exhaust gas vent 2 in c space heating supply 1 in d space...

  • Page 22: 4. System Details

    4. System details 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 boiler has two dip switch locations: on the main circuit board (pcb) and on the front panel. Each loca...

  • Page 23

    20 ncb service manual version 1.0 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 1 temperature control return water 1-on supply water 1-off 2 reserved - - 3 rese...

  • Page 24

    Setting the front panel dip switches before change the settings, lift the rubber cover to access the front panel dip switches. 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. Application setting remark...

  • Page 25

    22 ncb service manual version 1.0 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 1 reserve 2 gas type natural gas 2-off propane gas 2-on.

  • Page 26

    4.2 measuring the inlet gas pressure warning the boiler cannot function properly without sufficient inlet gas pressure. Measuring the inlet gas pressure should be performed by a licensed professional only. The inlet gas pressure must be maintained between 3.5” and 10.5” wc for natural gas and betwee...

  • Page 27

    24 ncb service manual version 1.0 6. Re-open the manual gas valve and check for leaks. 7. Open multiple fixtures that have high flow rates, such as bathtub and shower faucets, to allow the boiler to operate up to its maximum firing rate. 8. When the boiler reaches its maximum firing rate, check the ...

  • Page 28

    In cubic feet (ft 3 ) per hour (0.60 specific gravity; 3.0” wc pressure drop). Contact your gas supplier for btu/ft 3 ratings. Use 1,000 btu/ft3 for simplified calculations. This table is recommended for supply pressures of 6” wc or greater. Pipe size length (including fittings) 10' (3m) 20' (6m) 30...

  • Page 29

    26 ncb service manual version 1.0 4.3 gas conversion ncb series boilers are configured for use withnatural gas from the factory. If conversion to propane gas is required, the conversion kit supplied with the boiler must be used. Warning this conversion kit shall be installed by a qualified service a...

  • Page 30

    7. Remove the pcb assembly. Figure 3. Access to gas orifice in fan assembly 8. With the internal components exposed, locate the gas inlet pipe and the gas valve in the middle of the unit, as shown below 9. Use a phillips screwdriver to remove the two screws at location a - the connection below the g...

  • Page 31

    28 ncb service manual version 1.0 warning do not adjust or attempt to measure gas valve outlet pressure. The gas valve is factory-set for the correct outlet pressure. This setting is suitable for natural gas and propane, requiring no field adjustment. Attempting to alter or measure the gas valve out...

  • Page 32

    14. Place the pcb assembly back on to the boiler and tighten the three screws. 15. Check the labels carefully and then connect all the wires. 16. For lp, set dip sw2 #2 to on. For ng, set dip sw2 #3 to off. Warning ensure that you have turned off the power to the boiler before accessing the dip swit...

  • Page 33

    30 ncb service manual version 1.0 c. Fully open several hot water fixtures and set the boiler to operate at 1-stage min mode (refer to “setting the dip switches” on page 19 and operation condition setting on page 54). Measure the co 2 value at low fire. If the co 2 value is not within 0.5% of the va...

  • Page 34

    C. Fully open a hot water fixture and set the boiler to operate at 1-stage min mode (refer to page19 and page 54). Measure the offset value at low fire and compare it to the values in table . If the offset value is out of range, the gas valve set screw will need to be adjusted. If adjustment is nece...

  • Page 35

    32 ncb service manual version 1.0 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 heating displays heating ...

  • Page 36

    Segment status display function remarks wait shown while waiting for a response from the main controller when the boiler performs an error test or error history load rst shown on error reset clr shown on deleting the error history and parameters. Init shown on factory reset 4.4.2 buttons button desc...

  • Page 37

    34 ncb service manual version 1.0 long key combination function remarks [power] long key (300msec) power on / off [mode] long key (2 seconds) error history display must be in normal mode or error display mode [reset] long key (5 seconds) individual deletion of error history / tech data works only at...

  • Page 38

    4.4.3 turning the boiler on or off to turn the boiler on or off, press the [power] button. If the unit is experiencing an error the error code will continue to display on the front panel even if the unit is turned off. Item description display power on normal operating mode with power turned on when...

  • Page 39

    36 ncb service manual version 1.0 item description display 1. Normal status normal operating mode with power on 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 when the supply...

  • Page 40

    4.4.5 error display and reset 1. When an error higher than level 2 occurs (the boiler may stop operation or only has basic functions), the boiler enters directly at operating mode> or . 2. When an error occurs at other panel modes, only the error icon flashes and it enters after terminating the curr...

  • Page 41

    38 ncb service manual version 1.0 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. The default space heating supply wa...

  • Page 42

    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 (a) space heating supply water temperature disp...

  • Page 43

    40 ncb service manual version 1.0 item description display (e) flow rate display of the current flow rate minimum display unit (0.2 gal/min or l/min) using sensor gpm flow rate display ex) 10.2gpm (f) outdoor air temperature (with optional outdoor temperature sensor only) display of current outdoor ...

  • Page 44

    4.4.9 error occurrence history display 1. At the or mode>, press the [info] button for over 2 seconds to access the error history mode. The most recent error will be displayed first. 2. When the [+] / [-] button is pressed, the error history can be searched. A total of 10 errors are stored in memory...

  • Page 45

    42 ncb service manual version 1.0 4.4.10 information display (for servicer) 1. At the , 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. The cu...

  • Page 46

    Item description display (e) flow rate display of the current flow rate minimum display unit (0.2 gal/min or l/min) using sensor gpm flow rate display ex) 10.2gpm (f) outdoor air temperature (with optional outdoor temperature sensor only) display of current outdoor temperature outdoor temperature di...

  • Page 47

    44 ncb service manual version 1.0 item description display (j) heat capacity display of current heat capacity % range: 50~100% default : 100% % heat capacity display in percentage ex) 100%, (k) flame state display of flame detection current ad value flame on : below 70 flame off : over 175 displays ...

  • Page 48

    Item description display (q) model and capacity currently set model and capacity display the 2nd & 3rd digits represent the model and the 4th digit represents the type of market. Ex) capacity 180, condensing for the american market ex) capacity level 240, for the korean market ex) setting error (r) ...

  • Page 49

    46 ncb service manual version 1.0 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 availabl...

  • 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” if you make no adjustment for 10 seconds in the parameter edit mode, the current p...

  • Page 51

    48 ncb service manual version 1.0 item description display (c) lowest outdoor temperature setting 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. Outdoor low temperature settin...

  • Page 52

    Item description display (g) pump freezing temperature setting this menu is used to configure the circulation pump freeze protection 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 freeze dam...

  • Page 53

    50 ncb service manual version 1.0 item description display (l) ch burning off differential during space heating, the boiler turns off the burner when the space heating supply temperature meets or exceeds the burner-off temperature. Setting range default 0-54℉(0-30℃) 0℉(0℃) for celsius (℃) mode; ex) ...

  • Page 54

    Item description display (q) return absolute min set-point 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 changes based on the return absolute ...

  • Page 55

    52 ncb service manual version 1.0 (2) error checking mode 1. While in , press the [+] / [-] button and then press the [mode] button once “2.Tst” is displayed on the front panel. 2. After accessing , make sure that the boiler is not operating (stop flow) 3. Increase / decrease and change the componen...

  • Page 56

    Component test performed display method fan gradually increase / decrease the speed of the fan motor starting from 0 rpm to full speed and back down to 0 rpm the current aps value and the current rpm value are repeatedly displayed at intervals of 2 seconds. Pump cycles the pump 10 seconds on and 5 s...

  • Page 57

    54 ncb service manual version 1.0 (3) operation conditions settings 1. While in , 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 ...

  • Page 58

    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. If resetting the boiler does not solve the problem, refer to the troubleshooting section of this manual or contact technical ...

  • Page 59

    56 ncb service manual version 1.0 4.7 ladder diagram hot neutral emi filter relay 1 relay 2 relay 3 relay 4 relay 5 venturi igniter pump 3 way fan speed control primary secondary auto water supplement flame rod flow sensor aps fan hall sensor dhw inlet thermistor 1 dhw outlet thermistor 2 heating su...

  • Page 60

    4.8 electrical diagnostic point & wiring diagram fl am e r od pum p spa rk el ect ro de gr ou nd pow er c od e gr ou nd (gy ) neu tr al (w ) h ot (b k) sol en oi d val ve 3- w ay v al ve o pt io na l ex te rn al p owe r w ire (1a , 120w ) fu se (5 a) d ual v en tu ri m ai n g as v al ve ac 24v , m a...

  • Page 61

    58 ncb service manual version 1.0 point function cn no. Wire color normal value check a dhw inlet temperature sensor cn13 1-2 blue-blue dc 0~5v voltage changes according to temperature. Heating return temperature sensor cn13 3-4 blue-blue dc 0~5v voltage changes according to temperature. Dhw outlet ...

  • Page 62

    Point function cn no. Wire color normal value check j power input cn1 1-2 white-black ac 97~138v confirm appropriate power source. Confirm the fuse. Confirm the circuit breaker. K igniter cn17 1-2 blue-blue on : ac 97~138v off : 0v confirm voltage when the unit is igniting. L pump cn18 1-3 yellow-wh...

  • Page 63

    60 ncb service manual version 1.0 4.9 key components description 4.9.1 pcb part check point function to control each component and also to check the overall performance of the unit. Failure event malfunctioning pcb. Effects a component may not operate within the unit and could produce an error code....

  • Page 64

    4.9.2 high limit switch check point check point function 1. Overheat prevention switch. 2. If the unit detects extremely high temperatures, it will automatically trip and shut down the unit. 3. Excessively high water temperatures (more than 197.6 °f or 92 °c) in heat exchanger will activate the high...

  • Page 65

    62 ncb service manual version 1.0 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. Effects 1. If any of the thermistors fail, an error cod...

  • Page 66

    4.9.4 fan motor part check point function to provide combustion air into the burner and to purge exhaust flue gas. To maintain 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 scre...

  • Page 67

    64 ncb service manual version 1.0 4.9.5 flame rod assembly part check point function to ignite gas by repeatedly discharging a high voltage spark to the main burner until gas ignites. Failure event 1. Unable to ignite during the ignition process. 2. Produces multiple unsuccessful attempts to ignite....

  • Page 68

    4.9.6 ignition transformer part check point function to ignite gas by repeatedly discharging a high voltage spark to the main burner until gas ignites. Failure event 1. Unable to ignite during the ignition process. 2. Produces multiple unsuccessful attempts to ignite. Effects 1. The unit cannot igni...

  • Page 69

    66 ncb service manual version 1.0 4.9.7 aps part check point function detecting the air pressure entering the burner system. Failure event 1. Combustion noise occurs. 2. Imperfect and/or abnormal flame occurs. 3. Occurs when aps does not detect proper voltage. Effects 1. The boiler is not operating....

  • Page 70

    4.9.8 main gas valve part check point function 1. To control the amount of gas supplied to the burner based on fan speed. 2. When the unit experiences abnormal combustion, it shuts off the gas valve automatically and prevents unsafe situations. Failure event unable to open/close effects 1. No flames...

  • Page 71

    68 ncb service manual version 1.0 4.9.9 burner part check point function 1. Pre-mix system reduces emissions and increase efficiency. 2. The burner facilitates the air/gas mixture necessary to produce the proper heat during combustion. Failure event 1. Unable to initialize/sustain combustion. 2. Dus...

  • Page 72

    4.9.10 flow sensor part check point function to detect water flow in gpm (gallons per minute) for steady hot water temperatures. Failure event 1. Unable to detect or measure water flow rate. 2. Damage to and/or water leakage from the water flow sensor. Effects 1. Ignition sequence does not start. 2....

  • Page 73

    70 ncb service manual version 1.0 4.9.11 primary heat exchanger part check point function 1. Main part for heat transfer from the burner. 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. Failure event 1. ...

  • Page 74

    4.9.12 secondary heat exchanger part check point function 1. Main part for heat transfer from the burner. 2. There are multiple paths of water pipes on the heat exchanger as well as inside the combustion chamber which minimizes heat loss. Failure event 1. Water and/or exhaust gas leakage through a c...

  • Page 75

    72 ncb service manual version 1.0 4.9.13 dhw heat exchanger part check point function water heated in the primary/secondary heat exchanger is circulated to the plate heat exchanger, where the heat of heating water and tap water are exchanged so that hot water is available failure event 1. Water leak...

  • Page 76

    4.9.14 circulation pump part check point function 1. Pump operates when using internal or external hot water circulation. 2. Internal circulation will minimize the effect of temperature fluctuations and external circulation delivers hot water to fixtures quickly resulting in water conservation. Fail...

  • Page 77

    74 ncb service manual version 1.0 4.9.15 3-way valve part check point function diverts the water from the space heating system to the dhw plate heat exchanger and back based on input from dhw flow sensor and pcb. Failure event 1. No hot water in space heating mode. 2. No domestic hot water in dhw mo...

  • Page 78

    4.9.16 water pressure sensor part check point function they are suitable for analyzing water pressure ratios in heating. Failure event unable to detect or measure to change water pressure effects water filling system does not operate automatically error code e351, e352, e353 diagnostic 1. Visual ins...

  • Page 79

    76 ncb service manual version 1.0 4.9.17 auto feeder valve part check point function detect low and high water pressure using the electronic water pressure sensor if water pressure is low, water filling system operates automatically failure event 1. Water filling system does not operate automaticall...

  • Page 80: 5. Troubleshooting

    5. Troubleshooting 5.1 error code classification classification error code error level function self-diagnostic/action combusition system e003 3 ignition failure manual reset e004 2 false flame detection auto reset e012 3 flame loss manual reset e016 3 overheating of heat exchanger manual reset e030...

  • Page 81

    78 ncb service manual version 1.0 5.2 error code list error code function self-diagnostic/action e003 ignition failure 1. Check to see if the main gas supply valve is open. 2. Check that the power is “on”. 3. Check the igniter for spark. 4. Tighten the ground connection screws on heat exchanger. E00...

  • Page 82

    Error code function self-diagnostic/action e351 abnormal auto feeder valve (make-up water) check the auto feeder valve e352 high water pressure check the auto feeder valve e353 abnormal operation: water pressure sensor check the water pressure sensor. E407 hot water outlet: thermistor open or short ...

  • Page 83

    80 ncb service manual version 1.0 5.2.1 003error error occurrence conditions and check items error description e003 ignition failure in the case of an ignition failure, the boiler will attempt ignition 10 times. If no flame is detected, the system displays the error message 003e (manually cleared) o...

  • Page 84

    Scenario2 scenario3 is the flame detection device normally operating? Is the flame current detected? Clean or replace the flame rod check whether ground circuit is properly installed. Restart unit check the current #1 of cn 2: dc 1 - 20μa (see page 56 for wiring diagram) check connector (#1 of cn2) ...

  • Page 85

    82 ncb service manual version 1.0 check method failure mode cause check method ignition failure gas supply error 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. 3. Check the flexible ...

  • Page 86

    Failure mode cause check method ignition failure ignite gap distance : 3.5~4.5mm (1/8”) no spark from electrode 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 me...

  • Page 87

    84 ncb service manual version 1.0 failure mode cause check method ignition failure main gas valve 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. 3. If power supply is normal,...

  • Page 88

    Failure mode cause check method repeated ignition-out flame sensing error 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. 3. Check the grounding to the boiler case to ve...

  • Page 89

    86 ncb service manual version 1.0 5.2.2 004error error occurrence conditions and check items error description e004 false-flame detection 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 0...

  • Page 90

    5.2.3 012error error occurrence conditions and check items error description e012 flame loss if the system detects loss of flame during combustion, the system stops supplying fuel, attempts to restart, counts the incidents of flame loss, and if the incident occurs 20 times consecutively displays 012...

  • Page 91

    88 ncb service manual version 1.0 check method fault possible causes check method flame loss and noise occurs after ignition low gas supply pressure 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 pressu...

  • Page 92

    Fault possible causes check method flame loss and noise occurs after ignition flame loss during 2nd stage blockage in the gas orifice plate. Flame loss will occur if the gas orifices are clogged. Remove the gas inlet pipe and check for debris; remove and clean the orifice plate if necessary. Other t...

  • Page 93

    90 ncb service manual version 1.0 5.2.4 016error error occurrence conditions and check items error description e016 bimetal overheated if the overheat controller on the heat exchanger is initiated during combustion/standby of the boiler, the system displays the 016e (manually cleared) message on the...

  • Page 94

    Check method fault possible causes check method defective safety device defective overheat controller check if the contact point of the overheat controller is defective. Use a multi-meter to see if the resistance is normal (0.3Ω) or abnormal (∞). Overheat controller check if the overheat controller ...

  • Page 95

    92 ncb service manual version 1.0 5.2.5 030error error occurrence conditions and check items error description e030 exhaust gas temperature error if the overheat controller on the top of the exhaust duct is initiated, the system displays the heat exchanger bimetal overheat message 030e (cleared manu...

  • Page 96

    Check method fault possible causes check method heat exchanger overheated damaged or clogged heat exchanger 1. The error occurs due to high exhaust gas temperature caused by a damaged or clogged heat exchanger. 2. Flush the heat exchanger to remove scale deposits. 3. Replace the heat exchanger if it...

  • Page 97

    94 ncb service manual version 1.0 5.2.6 046error error occurrence conditions and check items 5.2.7 047error error occurrence conditions and check items replace exhaust thermistor yes is exhaust thermistor operating normally? Check connector (#9 and #10 of cn13) no resistance between #9 and #10 of cn...

  • Page 98

    5.2.8 060error error occurrence conditions and check items error description e060 dual venturi error this error message is displayed on the front panel if the wiring is disconnected or the dual venturi malfunctions. The boiler switches into lock-out, and performs post-purge continuously and operates...

  • Page 99

    96 ncb service manual version 1.0 check method fault possible causes check method dual venturi action error defective dual venturi cable or harness 1. Disconnect all cables from the dual venturi. 2. Using a multi-meter, test the dual venturi electrical wiring. Dual venturi not operating 1. Turn off ...

  • Page 100

    5.2.9 109error error occurrence conditions and check items error description e109 fan motor rpm error 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 deter...

  • Page 101

    98 ncb service manual version 1.0 check method fault possible causes check method fan action error no fan operation 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 unit and then wait for at le...

  • Page 102

    5.2.10 110error error occurrence conditions and check items error description e110 air pressure error the system senses the air volume and the rpm signal, and displays 110e on the front panel in the following cases: 1. When the initial fan auto-adjust is not performed. 2. When the unit capacity reac...

  • Page 103

    100 ncb service manual version 1.0 check method fault possible causes check method 110e exhaust blockage abnormal flow of intake air supply / exhaust 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...

  • Page 104

    Check method fault possible causes check method defective sensor defective temperature sensor connector check if the temperature sensor is open and if the connector is connected properly. Temperature sensor check the resistance of the temperature sensor. (defective if it is 30kΩ or higher) replace t...

  • Page 105

    102 ncb service manual version 1.0 5.2.12 218error error conditions and check items error description e218 heat exchanger input temperature sensor open if an error (open: 14°f (-10°c) or lower) in the heat exchanger input temperature sensor is detected, the system displays the 421e error on the fron...

  • Page 106

    Check method fault possible causes check method defective sensor defective temperature sensor connector check if the temperature sensor is open and if the connector is connected properly. Temperature sensor check the resistance of the temperature sensor. (defective if it is 30kΩ or higher) replace t...

  • Page 107

    104 ncb service manual version 1.0 5.2.13 351error error conditions and check items error description e351 abnormal auto feeder valve if the water pressure sensor senses low water level as the heating pipe pressure is low, the system stops operation of the boiler, and refills water automatically. If...

  • Page 108

    Check method fault possible causes check method water is not refilled cold water valve is closed or frozen turn on cold water tap and check if the valve works or is frozen. Water is not refilled defective auto feeder valve 1. Check the auto feeder valve filter if water is not refilled. 2. Check the ...

  • Page 109

    106 ncb service manual version 1.0 5.2.14 352error error conditions and check items error description e352 high water pressure upon receiving a signal from the water pressure sensor, the system displays the error(e352) on front panel. High water level error if the water level of 56.6psi or higher co...

  • Page 110

    5.2.15 353error error conditions and check items error description e353 abnormal water pressure sensor if an error (under 0.3v or over 2.8v) in the water pressure sensor is detected continuously for 3 seconds, the system displays the error message e353 on the front panel. If this occurs, the boiler ...

  • Page 111

    108 ncb service manual version 1.0 5.2.16 407error error conditions and check items error description e407 hot water outlet thermistor open or short if an error (open: 14°f (-10°c) or lower) in the dhw outlet elbow input temperature sensor is detected, the system displays the 407e error on the front...

  • Page 112

    Check method fault possible causes check method defective sensor defective temperature sensor connector check if the temperature sensor is open and if the connector is connected properly. Temperature sensor check the resistance of the temperature sensor. (defective if it is 30kΩ or higher) replace t...

  • Page 113

    110 ncb service manual version 1.0 5.2.17 421error error conditions and check items error description e421 cold water inlet thermistor open or short if an error (open: 14°f (-10°c) or lower) in the dhw outlet elbow input temperature sensor is detected, the system displays the 421e error on the front...

  • Page 114

    Check method fault possible causes check method defective sensor defective temperature sensor connector check if the temperature sensor is open and if the connector is connected properly. Temperature sensor check the resistance of the temperature sensor. (defective if it is 30kΩ or higher) replace t...

  • Page 115

    112 ncb service manual version 1.0 5.2.18 439error error occurrence conditions and check items error description e439 flow sensor error as one or more units are operating in the cascade system, if no flow is detected during dhw using, the system considers it as a defective flow sensor. The system di...

  • Page 116

    Check method fault possible causes check method no hot water flow cold water supply error 1. Check if the cold water line is frozen. 2. Check if the cold water filter is clogged. Boiler not working defective flow sensor 1. Check the current flow displayed on the front panel. If the flow sensor is de...

  • Page 117

    114 ncb service manual version 1.0 5.2.19 515error error occurrence conditions and check items error description e515 error if an error occurs in the internal circuit of the pcb (e.G., resistance, transistor or relay fault), the system displays 515e (cleared manually) on the pcb. Check items 1. Defe...

  • Page 118

    5.2.20 517error error occurrence conditions and check items 5.2.21 594error error occurrence conditions 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 check...

  • Page 119

    116 ncb service manual version 1.0 5.2.23 740error error conditions and check items error description e740 abnormal outdoor sensor if an error (under 2.2kΩ or over 122.2kΩ) in the outdoor sensor is detected continuously for 3 seconds, the system displays the error message e740 on the front panel. If...

  • Page 120

    5.2.24 777error error conditions and check items 5.2.25 782error error occurrence conditions and check items is the wiring from the front panel properly connected to the pcb? Reconnect panel to the pcb 1. Step: reset the unit. 2. Step: if problem persists, replace the pcb and front no yes yes yes is...

  • Page 121

    118 ncb service manual version 1.0 5.3 troubleshooting guide by symptom 5.3.1 noise error type cause check method vibration noise defective installation incorrect mounting to the wall or in an improper location. Check for improper installation and reinstall the unit if necessary. Fan vibration noise...

  • Page 122

    5.3.2 water temperature issue error type cause check method boiler is not operating properly. Front panel power off hot water does not run if the front panel is switched off. Defective flow sensor the boiler does not work due to the defective flow sensor. The flow sensor impeller will not rotate if ...

  • Page 123

    120 ncb service manual version 1.0 5.3.3 circuit breaker operation error type cause check method circuit breaker trips power supply the circuit breaker trips immediately as soon as the power cord is plugged in the receptacle. Check the sheath of power cord, or if there is short-circuit. Check the co...

  • Page 124: 6. Replacement Of Parts

    6. Replacement of parts 6.1 replacement procedure caution 1. When performing maintenance and/or servicing the boiler, always turn off the electric power, gas and water shut-off valve. Wait for the boiler to become cool. Be careful to avoid injury to your fingers on sharp edges. 2. Drain all water fr...

  • Page 125

    122 ncb service manual version 1.0 7. Remove the old pcb and replace it with the new part. 8. Reattach all wiring connectors to the pcb. 9. Set the proper dip s/w settings on the pcb (refer to page 121). 10. Reinstall the pcb and front panel using the 7 screws previously removed. 11. Turn on the wat...

  • Page 126

    8. Remove the four screws from the bottom of the fan assembly. Figure 6 9. Detach the fan motor from the assembly and replace it with the new part. 10. Replace the 4 screws used to attach the fan motor to the assembly. 11. Reinstall the fan assembly to the bracket by using the mounting screw. 12. At...

  • Page 127

    124 ncb service manual version 1.0 note always use new factory gaskets included with the flame rod when replacing the part onto the burner assembly. 6.2.5 ignition transformer 1. Turn off the gas supply to the unit. 2. Disconnect the unit from the power supply. 3. Turn off the water supply to the un...

  • Page 128

    5. Remove the hose from the air pressure sensor. Figure 12 6. Remove the 2 screws that attaches the air pressure sensor to the burner assembly. 7. Pull out the air pressure sensor. 8. Replace the old air pressure sensor with the new part. 9. Reattach the air pressure sensor hose. 10. Connect the air...

  • Page 129

    126 ncb service manual version 1.0 7. Remove the 4 screws directly from the bottom of the gas valve to remove the elbow. Figure 16 8. Replace the o-ring where the gas valve assembly attaches to the elbow. Make sure the old o-ring is discarded. 9. Replace the old gas valve with the new part and reatt...

  • Page 130

    6.2.9 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. Remove the main gas valve (refer to page 125) 5. Remove the stainless fastener. Figure 18 6. Remove two screws of d...

  • Page 131

    128 ncb service manual version 1.0 5. Remove the stainless nut, fastener and circulation pump wiring connector (figure 22). Figure 22 6. Carefully remove the pump. Figure 23 7. Remove the air vent.. Figure 24 8. Replace with the new circulation pump (or air vent). 9. Place the new pump back into its...

  • Page 132

    6. Remove the two screws on the bottom of case. Figure 26 6.2.12 water pressure sensor 1. Turn off the gas supply to the unit. 2. Turn off the 120v power supply to the unit. 3. Turn off the water supply to the unit. Drain all water from the appliance. 4. Disconnect the water pressure sensor wire hou...

  • Page 133

    130 ncb service manual version 1.0 6.2.14 auto feeder valve 1. Turn off the gas supply to the unit. 2. Turn off the 120v power supply to the unit. 3. Turn off the water supply to the unit. Drain all water from the appliance. 4. Remove the siphon 5. Disconnect the wiring connector, fastener and remov...

  • Page 134

    7. Components diagram and part list 7.1 case assembly # description part # remark 1 intake air duct assembly 30008662b 2 exhaust pipe assembly 30008673a 3 case 20027375a 4 intake air filter 20007668a 5 air pressure sensor 30010346a 6 pcb 30012262a 7 front panel 30012269a 8 cover 30012276a.

  • Page 135

    132 ncb service manual version 1.0 7.2 burner assembly.

  • Page 136

    # description part # remark 1 damper 30008825a 2 o-ring (g50) 20003019a 3 fan bracket 20022095a 4 siphon 30012280a 5 burner chamber ass'y 30010353a ncb-180 30008440a ncb-210/240 6 ignition transformer 30010455a 7 burner packing 20021677a ncb-180 20021672a ncb-210/240 8 heat exchanger ass'y 30012322a...

  • Page 137

    134 ncb service manual version 1.0 7.3 waterway assembly # description part # remark 1 dhw heat exchanger 30008181a ncb-180 30005017a ncb-210/240 2 thermistor 30008366a 3 o-ring (p18) 20006954a 4 dhw outlet elbow 30012328a 5 packing 20006852a 6 thermistor 30008366a.

  • Page 138

    # description part # remark 7 dhw outlet adpator 30003747a 8 dhw flow sensor 30012033a 9 o-ring (p14) 20006952a 10 dhw cold water adaptor 30010317a 11 o-ring (p20) 20017212a 12 dhw cold water filter - 13 air vent 30012277a 14 auto fill valve 30012241a 15 o-ring (p16) 20011438a 16 fastener 20007859a ...

  • Page 139

    136 ncb service manual version 1.0 7.4 fan (gas) assembly.

  • Page 140

    # description part # remark 1 fan assembly 30008834a 2 fan packing 20022744a 3 o-ring (g75) 20018079a 4 dual venturi 30009219a ncb-180 30008909a ncb-210/240 5 silence 20019142a ncb-180 20023829a ncb-210/240 6 silence adaptor 20023861a ncb-180 20019141a ncb-210/240 7 venturi packing 20022660a ncb-180...

  • Page 141

    138 ncb service manual version 1.0 8. Inspection and maintenance schedule 8.1 annual servicing in order to maintain its safe and efficient operation, it is recommended that the boiler is serviced annually. Caution servicing must be performed by a qualified service agency or gas supplier inspection v...

  • Page 142: Memo

    Memo.

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    140 ncb service manual version 1.0 memo.

  • Page 144: Memo

    Memo.

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    142 ncb service manual version 1.0 memo.

  • Page 146: Memo

    Memo.

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    144 ncb service manual version 1.0 memo.

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    Memo.

  • Page 149: Memo

    146 ncb service manual version 1.0 memo.