Navien NCB300-28K Service Manual Download Page 1

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Navien LTD

Building 2, Guildford Business Park, Guildford, GU2 8XH

TEL 0844 332 2323 www.navien.co.uk

Getting Service

If your boiler requires service, you have several options for getting service:

●

Contact an official Technical Assistance Service (TAS) at 0844 332 2323 or go to the website

(www.navien.co.uk).

For warranty service, always contact an official Technical Assistance Service (TAS) first.

●

Contact the technician or professional who installed your boiler.

●

Contact a Gas Safe Registered engineer.

When contacting an official Technical Assistance Service (TAS), please have the following information

available:

●

Model number

●

Serial number

●

Date purchased

●

Installation location and type

●

Error code, if any appears on the front panel display

Condensing Combi Boiler

Service Manual

Version: 1.0(September, 2022)

Summary of Contents for NCB300-28K

Page 1: ...uk For warranty service always contact an official Technical Assistance Service TAS first Contact the technician or professional who installed your boiler Contact a Gas Safe Registered engineer When...

Page 2: ...petrol or other flammable vapours and liquids in the vicinity of this or any other appliance WHATTO DO IFYOU SMELL GAS Do not try to light any appliances Do not touch any electrical switch do not use...

Page 3: ......

Page 4: ...Revisions 3 Version Description of changes Date 1 00 First issue September 7 2022 Revisions...

Page 5: ...ondary Heat Exchanger 47 4 7 12 DHW Heat Exchanger 48 4 7 13 Circulation Pump 49 4 7 14 3 Way Valve 50 4 7 15 Water Pressure Sensor 51 4 7 16 Expansion tank 52 5 Troubleshooting 53 5 1 Error Code Clas...

Page 6: ...er or distributor not authorised by Navien Failure to perform regular maintenance misuse operation at settings other than those recommended or specified non compliance with instructions or guidelines...

Page 7: ...l Gas LP Propane Gas AP Air Pressure APS Air Pressure Sensor DHW Domestic Hot Water FM Fan Motor GARC Gas Air Ratio Control LPM Litre Per Minute MGV Main Gas Valve RPM Revolutions per Minute PCB Print...

Page 8: ...bour s phone call your gas provider and follow their instructions If you cannot reach your gas provider call the fire department Do not return to your home until authorised by your gas supplier or the...

Page 9: ...explosion Do not place combustibles such as newspapers or laundry near the boiler or flue system Doing so may result in a fire Do not place or use hair sprays spray paints or any other compressed gas...

Page 10: ...Very low scald risk CAUTION Do not turn on the boiler unless the water and gas supplies are fully opened Doing so may damage the boiler Do not turn on the water if the cold water supply shut off valv...

Page 11: ...ural gas If LPG conversion is required use the conversion kit supplied with the boiler and attach the item matching the LPG GC No included in the kit The Codes of good practice and regulations refer t...

Page 12: ...26 8 kW 37 0 kW NCB300 41K 26 8 kW 41 0 kW By default the boiler assigns system priority to DHW supply The NCB300 Series boiler has a built in circulation pump 3 way valve assembly flow sensor DHW pl...

Page 13: ...ents The following diagram shows the key components of the boiler Component assembly diagrams and particular parts lists are included in the Appendices Fan Motor Front Panel Ignitor Flame Rod Circulat...

Page 14: ...le Venturi Mixing Chamber Primary Heat Exchanger Secondary Heat Exchanger Return Adapter Filter Assembly Gas Valve Central Heating Return Pressure Relief Valve Central Heating Supply DHW Inlet DHW Out...

Page 15: ...14 Product Information Fan Motor Front Panel Ignitor Flame Rod Circulation Pump Gas Valve PCB NCB300 37K NCB300 41K...

Page 16: ...nturi Mixing Chamber Primary Heat Exchanger Secondary Heat Exchanger Return Adapter Filter Assembly Gas Valve Central Heating Return Pressure Relief Valve Central Heating Supply DHW Inlet DHW Outlet 3...

Page 17: ...fication Class 6 Category II2HY203P Type Heating and instantaneous hot water production Heat output adjustment Adjustable over entire Max Min output range Type of heating installation Close circuit Ma...

Page 18: ...alent elbow length 45 60 100 m 1 0 Max horizontal coaxial length 80 125 m 27 Max vertical coaxial length 80 125 m 28 Equivalent elbow length 90 80 125 m 2 2 Equivalent elbow length 45 80 125 m 1 0 Equ...

Page 19: ...ust Air intake 60 100 80 125 B Central heating supply 22 mm C Hot water outlet DHW 15 mm D Gas supply inlet 22 mm E Cold water inlet DHW 15 mm F Central heating return 22 mm OverheadView A 197 5 mm 28...

Page 20: ...ircuit board configures boiler type capacity burner type country and discharge of condensate function 1 2 3 4 5 6 7 8 ON DIP SW1 Switch Function Setting 1 Boiler Type SOLO ON COMBI OFF 2 Reserve 3 4 C...

Page 21: ...for Natural gas G20 Allowing for the acceptable pressure loss of 1 mbar across the installation pipework it can be assumed that a minimum permitted operating pressure of 18 mbar will be delivered to t...

Page 22: ...ponsible for the connection utilization repair or servicing of gas utilization equipment or accessories who is experienced in such work familiar with all precautions required and has complied with all...

Page 23: ...e Once the hex nut is loose carefully separate the pipe from the gas valve Procedure 1 Turn off both gas and water supply to the boiler 2 Unfasten the two latches at the top and remove two screws at t...

Page 24: ...e is detached from the gas valve find location B the connection above the gas valve where it is attached to the fan motor assembly Carefully remove the two screws by hand using a Phillips screwdriver...

Page 25: ...6 Set the DIP switches Switch Function Setting 1 2 Fuel Selection G20 LNG 1 OFF 2 OFF G30 LPG 1 ON 2 OFF G31 LPG 1 ON 2 ON Table 1 The DIP Switch Setting by Fuel Selection DANGER When conversion is r...

Page 26: ...s on page 34 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 proper Gas Orifice DANGER Improper gas valve settings can...

Page 27: ...ation required for the boiler s operation Refer to the following table for detailed information b a d f c g e a Outdoor temperature compensation OTC Displayed when the outdoor temperature compensation...

Page 28: ...emperatures Refer to the following table for detailed information a b c d e f a Menu button Access to the Main menu screen b Eco button Turn the boiler DHW preheat on or off c Info button Access the b...

Page 29: ...supply water temperature range is 40 C Absolute MIN to 90 C Absolute MAX The central heating temperature cannot be adjusted when the Outdoor Reset Control is used The central heating temperature cann...

Page 30: ...stant scalding or severe burns To adjust the water temperature 1 In normal operation mode press the menu button twice The DHW demand icon blinks on the screen 2 Press the Plus button or the Minus butt...

Page 31: ...selected Item Description 1 ECO Mode Do not DHW Preheat 2 Non ECO Mode Always DHW Preheat 4 4 6 Accessing Basic Menu Items In the Main Menu screen you can view the boiler s operating conditions config...

Page 32: ...Flame detector AD value Flame On 8bit AD values equal to or lower than 70 Flame Off 8bit AD values equal to or higher than 175 A Target RPM Fan target speed RPM B Current RPM Fan speed RPM C Target AP...

Page 33: ...irm after making changes Press the Info button to return to the previous screen or menu Item Description A Supply MIN Set point Set the central heating supply minimum temperature Setting range 25 C MA...

Page 34: ...n or the Minus button to change numbers and places and press the ECO button to save the new password When the boiler is connected to an outdoor temperature sensor optional functioning may be activated...

Page 35: ...H MAX Set the boiler to run in central heating maximum operation mode oPE 3 DHW MAX Set the boiler to run in DHW maximum operation mode 4 4 7 2 Diagnosing the Boiler System To Set the boiler s operati...

Page 36: ...mp Dip s w 8pin Dip s w 4pin BURNER HTL M 7 6 5 4 3 2 1 8 MIX V V CN10 OUTLET_Temp 5 4 3 6 2 CN12 HTL INLET_Temp 2 3 4 CN8 1 CN2 M 7 6 5 4 3 2 1 8 WAV V V CN11 P E 1 2 3 4 1 6 7 8 5 1 0 1 1 1 2 9 1 4...

Page 37: ...ent Valve Flow Control DC15V Vent Separation Detector Supply Thermistor Outlet Thermistor 1 Return Thermistor UART Communication Interface FRONT PANEL Communication Interface FUSE Inlet Thermistor 1 E...

Page 38: ...the unit Fault PCB malfunction Symptoms A system component may not operate and generate an error code In most PCB failures the boiler will not operate until the fault is resolved Error codes E515 E61...

Page 39: ...ll activate the high limit switch Fault Unable to detect high water temperature conditions if the switch malfunctions Symptoms Unable to shut down the boiler if the water temperature from the heat exc...

Page 40: ...e outside the allowable range there will be hot water temperature fluctuations Error codes E047 E205 E218 E407 E421 Diagnostics 1 Visual inspection Check wire connections are secure and inspect for wi...

Page 41: ...y 0 rpm 2 A fan assembly screw is loose and or the fan is disassembled 3 Disconnected or defective fan connection terminal assembly Symptoms 1 Erratic combustion 2 Vibration and noise coming from the...

Page 42: ...ite the gas 2 Results in multiple unsuccessful ignition attempts Symptoms 1 The boiler does not ignite and error code E003 or E004 is displayed 2 The durability of the igniter reduces Error codes E003...

Page 43: ...toms 1 The boiler does not ignite and error code E003 or E004 is displayed 2 Durability of the transformer wears down Error codes E003 E004 Diagnostics 1 Visual inspection Check wire connections are s...

Page 44: ...o prevent unsafe situations Fault Unable to open close Symptoms 1 No flame 2 The boiler does not operate Error codes E003 E012 Diagnostics 1 Visual inspection Check wire connections are secure and ins...

Page 45: ...to initiate or sustain combustion 2 Dust or soot deposits form on the burner s surface 3 Gas leakage from the burner Symptoms 1 Abnormal combustion 2 Unstable flame conditions and or flame loss 3 Igni...

Page 46: ...etect or measure water flow rate 2 Damage to and or leakage from the water flow sensor Symptoms 1 Ignition does not start 2 Boiler operation stops when water leakage is detected Error codes E439 Diagn...

Page 47: ...amber are used to minimise heat loss Fault 1 Water and or exhaust gas leaks 2 Scale deposits in the heat exchanger can cause water in the boiler to bubble Symptoms 1 Exhaust gas leaks 2 Overheating of...

Page 48: ...he combustion chamber which minimises heat loss Fault 1 Water and or exhaust gas leaks 2 Scale deposits in the heat exchanger can cause water in the boiler to bubble Symptoms 1 Exhaust gas leaks 2 Ove...

Page 49: ...ger filters the water in the space heating system to prevent faults in other parts of the heating system Fault 1 Water leaks 2 Low temperature water in the heat exchanger Symptoms DHW leaks and or tem...

Page 50: ...r for obstructions 3 Voltage test Test the voltage meets the specifications shown below 4 Free a jammed pump rotor If a pump is not moving it may be a build up of debris in the pump which will prevent...

Page 51: ...toms DHW supply stops and flow continues in the space heating system when the space heating water temperature is lower than the set point Error codes E016 Diagnostics 1 Visual inspection Check the 3 w...

Page 52: ...o detect or measure changes of water pressure Symptoms The water top up system does not operate automatically Error codes E351 E352 E353 Diagnostics 1 Visual inspection Check the circulation pump s wi...

Page 53: ...escription Function 1 Removes air from the system during heating 2 Relieves system pressure caused by expansion as the water temperature increases 3 Uses a built in low level water sensor to maintain...

Page 54: ...ow water pressure Auto DHW Circulation E407 DHW Outlet thermistor Open or Short Circuit Alarm Controller PCB E515 Abnormal operation Relay feedback PCB Manual E517 Abnormal operation DIP switch settin...

Page 55: ...xchanger 6 Adjust the anti short cycle time E016 0 Heat exchanger overheat 1 Turn OFF the boiler wait at least 30 min and then restart the boiler 2 Clean the inlet water filter and strainer 3 Check th...

Page 56: ...heck the PCB E615 Abnormal operation Input and memory MCU E740 1 Abnormal operation Outdoor temperature sensor 1 Ensure that outdoor reset curve is correctly configured 2 Check the outdoor temperature...

Page 57: ...e circulation pump Run it in test mode 2 Check the operation of the 3 way valves Run it in test mode 3 Check if the heating strainer is obstructed 4 Check if the main heat exchanger or the DHW heat ex...

Page 58: ...structed by debris 2 Identify the type of debris caught in the strainer aluminium oxidised steel etc to help identify the cause of the obstruction Heating or DHW heat exchanger is obstructed 1 Disconn...

Page 59: ...and grounding 6 Check if the air pressure hose is broken or obstructed 7 Check if the air pressure sensor is operating correctly 8 Check the PCB DIP switch settings 9 Adjust the offset pressure 10 Ch...

Page 60: ...e correct Is the gas valve open Check the flame rod Turn OFF the boiler Check that the gas valve is open or check the LP supply Check the connections Test the voltage between WHITE YELLOW at CONZ1 DC...

Page 61: ...overtightened An overtight connection can deform the seal and obstruct the flow of gas 5 Check the class of pressure meter Digital pressure manometer Check gas supply pressure Deformed seal can obstr...

Page 62: ...ks in the insulator Adjust the gap if discharge is visible Ensure that the insulating gasket is fitted between the electrode and burner casing Check the input voltage at the ignition transformer AC 23...

Page 63: ...etween theYELLOW WHITE wires and verify the voltage is DC 24 V 2 If there is no voltage replace the PCB 3 If the voltage is correct check if the coil is open Check the resistance Check if the solenoid...

Page 64: ...ensure there is good contact with the case Use a multimeter to test the spark current normally 3 4 A Test the spark current connectors Ground connection Flame loss and noise occurs at ignition Check f...

Page 65: ...ed within the correct pressure range 4 Check the PCB and replace it if faulty Is there burner flame when there is no ignition External noise interference Clean or replace the flame rod Check the curre...

Page 66: ...count If flame loss occurs 20 times consecutively error code 012E is displayed manually cleared on the front panel Checklist 1 Use a manometer to measure the gas supply pressure NG 17 25 mbar LP 25 3...

Page 67: ...tightened An overtight connection can deform the seal and obstruct the flow of gas 4 Check the gas meter rating Flame loss and noise occurs after ignition PCB DIP switch setting error Check the PCB DI...

Page 68: ...urge and starts the circulation pump Checklist 1 Check the overheat controller is working correctly Test the resistance or continuity 2 Check the hot water temperature sensor 3 Test the circulation pu...

Page 69: ...ured at levels lower than it actually is test to confirm if the temperature sensor is faulty Check the output temperature displayed on the front panel 2 Measure the temperature sensor resistance and d...

Page 70: ...oller detects the exceeding temperature of 110 C for 10 minutes or more E030 is displayed and a post purge will be performed Automatically cleared 2 When the controller detects the exceeding temperatu...

Page 71: ...Defective overheat controller Faulty terminals on the exhaust gas overheat controller 110 C max Check the overheat controller s wiring connections If the resistance is incorrect replace the temperatu...

Page 72: ...stance within the normal range Replace heat exchanger thermistor Check connections Step 1 Flush clean Filter Step 2 Restart Step 3 Replace PCB Yes Yes No No 5 2 9 Error 047 Error Conditions and Checkl...

Page 73: ...ombustion and the boiler switches to Lock out mode The air volume sensor should be normal Checklist 1 Check if the fan motor works normally using the component test mode 2 Test the power supply to the...

Page 74: ...instructions below to replace the fan 1 Unplug the boiler s power cable and wait 10 sec for all remaining SMPS voltage to completely discharge 2 Disconnect the fan cable and then re connect it 3 Recon...

Page 75: ...ector is wet due to any reason including leakage 2 Replace the defective heat exchanger output temperature sensor 3 Check the circulation pump s operating status and the flow rate in the space heating...

Page 76: ...sor is faulty if the resistance is 30k or higher Replace the temperature sensor if the resistance value is abnormal Check the temperature displayed on the front panel Possible Issues Circulation pump...

Page 77: ...f the input water pressure sensor is wet for any reason including leakage 2 Check the auto feeder 3 Check the controller Is there a leak inside the boiler Is the water pressure sensor normal Check con...

Page 78: ...ected the system displays the 407E error on the front panel Check items 1 Check if the hot water temperature sensor connector is wet due to any reason and if the connector is connected properly 2 Chec...

Page 79: ...0k or higher Replace the temperature sensor if the resistance value is abnormal Check the temperature displayed on the front panel Possible Issues Defective PCB If the issues continue despite checking...

Page 80: ...valve Check the Fan voltage 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 In that same case replace the Main...

Page 81: ...items Check the PCB Error occurrence conditions and check items Fault Possible Causes Check method E594 Error Abnormal communication by PCB 1 Click the Reset button on Front panel 2 Turn the POWER to...

Page 82: ...from Reset Curve Mode to Normal Mode Check items 1 Check the parameter setting 2 Check the outdoor sensor Is the Outdoor sensor installed properly Is the outdoor thermistor normal Check connecter Chan...

Page 83: ...et the unit at MIN 1 If noise occurs at standard value adjust setting above 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 de...

Page 84: ...boiler The cold water temperature sensor may not be working properly Low hot water temperature Hot water setting error Check the hot water temperature setting on the front panel Water mixed with cold...

Page 85: ...if the wire is fixed and properly attached on the main side of the heat exchanger Circuit breaker trips Normal assembly Short circuit due to defective assembly Wiring near the heat exchanger Circuit...

Page 86: ...ce and operation after the boiler has been serviced 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...

Page 87: ...re to run the setup wizard and change to the existing setting 11 When the boiler is turned on press the Back button and the Menu button simultaneously for 3 seconds and then select 3 Parameter Setting...

Page 88: ...d gas supply to the unit Note Do not over tighten the screws for the fan motor replacement with high torque drill This may cause damage to the part s 6 2 3 Fan Motor Combustion Air 1 Turn off the gas...

Page 89: ...ower supply and gas supply to the unit Note Verify that the Ignition Transformer insulated cables are firmly connected to the flame rod 6 2 4 Flame Rod 1 Turn off the gas supply to the unit 2 Disconne...

Page 90: ...rt 9 Reconnect the hose to the condensate trap 10 Reattach the condensation trap to the unit and secure it using the five screws 11 Replace the front panel to its original position 12 Turn on the wate...

Page 91: ...re no leaks at the flow sensor connections 6 2 8 Circulation Pump 1 Turn off the gas supply to the unit 2 Disconnect the unit from the power supply 3 Turn off the water supply to the unit 4 Loosen the...

Page 92: ...essure sensor Figure 18 6 2 10 3 way Valve 1 Turn off the gas supply to the unit 2 Turn off the 230V power supply to the unit 3 Turn off the water supply to the unit Drain all water from the appliance...

Page 93: ...n all water from the appliance 4 Remove the gas supply unit 5 Remove the two screws at the DHW exchanger Figure 20 6 Replace with the new DHW Exchanger 5 Remove the clip on the WPS valve Figure 19 6 R...

Page 94: ...Remark 1 Cover 30030074A 2 Panel 30029172A 3 Controller 30028548A 4 Siphon 30029038A 5 Adapter 30029966A 6 Wind pressure sensor 30025533B 7 Tank 30029045A 8 Inlet adapter 30029947A 9 Valve 30030507A 1...

Page 95: ...ansformer 30029732A 5 Fuse 30025036A 6 Dual venturi 30029315A 3S 54K 30029314A 2S 42K 7 Outlet adapter 30029538A 8 Inlet adapter 30013743A 9 Clip 20007733B 10 Electrode 30030059A 11 Packing 20051913A...

Page 96: ...pply pipe 30029104A 9 Temperature sensor 30022222B 10 O ring 20033699A 11 Valve 30011532B 12 Clip 20033662A 13 Supply pipe 30029104A 14 3 way valve 30020637A 15 Heat exchanger 30029328A 30029327A 16 P...

Page 97: ...ng the Return Filter YES NO Checking the Intake Air Filter YES NO Flushing the Heat Exchanger YES NO Replacement of Parts 8 3 Maintenance Schedules Owner maintenance Daily Check boiler area Check pres...

Page 98: ...e lines per the Installation Operation Manual Inspecting the Boiler Interior 1 Remove the front cover and inspect the interior of the boiler 2 Vacuum any sediment from inside the boiler and components...

Page 99: ...Eliminate all system or boiler leaks Continual fresh makeup water will reduce boiler life Minerals can build up in sections reducing heat transfer overheating heat exchanger and causing heat exchanger...

Page 100: ...s pressure and gas rate are satisfactory either Perform the full service For more information refer to 8 5 2 Full Service on page 99 Set the Gas Valve For more information refer to 4 2 Measuring the I...

Page 101: ...rackets 6 Loosen the three screws holding the front panel and remove the front panel Note When removing the front panel label all wires and make sure all wires are disconnected 7 Use a Phillips screwd...

Page 102: ...solid support and be careful not to fall 13 As cleaning the heat exchanger is finished reassemble the parts 14 Check the CO For more information on measuring the CO refer to Checking the CO on page 9...

Page 103: ...r to commissioning As part of the installation process especially where a flue has been fitted by persons other than the boiler installer visually check the integrity of the whole flue system to confi...

Page 104: ...tegrity has been visually checked in accordance with the yellow Prior to CO and combustion ratio check box above before proceeding to the Check CO and combustion ratio at maximum rate stage below SET...

Page 105: ...o operate at combustion to stabilise CHECK CO AND COMBUSTION RATIO AT MINIMUM RATE gas sampling point Allow readings to stabilise before recording Is CO less than 350ppm and CO CO2 ratio less than 0 0...

Page 106: ...Memo...

Page 107: ...Memo...

Page 108: ...Memo...

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