Navien NHB Series Installation & Operation Manual
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Navien NHB Series Installation & Operation Manual

Condensing boilers
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Installation & Operation Manual
NFB Condensing Boilers
NFB-301C
Model
NFB-399C
WARNING
If the information in these instructions is not followed exactly, a fire or explosion may result, causing
property damage, personal injury, or death.
Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other
appliance.
WHAT TO DO IF YOU SMELL GAS
Do not try to light any appliance.
Do not touch any electrical switch; do not use any phone in your building.
Immediately call your gas supplier from a neighbor's phone. Follow the gas supplier's instructions.
If you cannot reach your gas supplier, call the fire department.
Installation and service must be performed by a qualified installer, service agency or the gas
supplier.
The installation must conform with local codes or, in the absence of local codes, the National Fuel
Gas Code, ANSI Z223.1/NFPA 54 and/or CSA B149.1, Natural Gas and Propane Installation Code.
Keep this manual near this boiler for future
reference whenever maintenance or service
is required.

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  • Page 1 Installation & Operation Manual NFB Condensing Boilers NFB-301C Model NFB-399C Keep this manual near this boiler for future reference whenever maintenance or service is required. WARNING If the information in these instructions is not followed exactly, a fire or explosion may result, causing property damage, personal injury, or death.
  • Page 2 Requirements for the State of Massachusetts NOTICE BEFORE INSTALLATION 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 4.00 and 5.00. IMPORTANT: In the State of Massachusetts (248 CMR 4.00 & 5.00) For all side wall horizontally vented gas fueled equipment installed in every dwelling, building or structure used in whole or in part for residential purposes, including those owned or operated by the Commonwealth and where the side wall exhaust vent termination is less than seven (7) feet above finished grade in the area of the venting, including but not limited to decks and porches, the following requirements shall...

  • Page 3: Table Of Contents

    9. Installing a Common Vent System 9.1 About the Common Vent System 2. Installing the Boiler 9.2 Navien Backflow Damper (Back-draft Damper) 2.1 Removing the Wood Pallet from the Boiler 9.3 Starting the Common Vent System 2.2 Choosing an Installation Location 9.4 Connecting and Terminating the Vent Pipe...
  • Page 4 Safety Information The following safety symbols are used in this manual. Read and follow all safety instructions in this manual precisely to avoid DANGER unsafe operating conditions, fire, explosion, property damage, personal injury, or death. DANGER Indicates an imminently hazardous situation which, if not avoided, could result in severe injury or death.
  • Page 5 CAUTION WARNING Do not turn on the boiler unless the water and gas supplies are fully opened. Doing so may damage the boiler. Do not use this boiler for anything other than its intended purpose, as described in this manual. Do not remove the front cover unless the power to the boiler is turned off or disconnected.

  • Page 6: About The Boiler

    1. About the Boiler 1.1 Included Items When you open the box, you will find the following items with the boiler. Check the box for each of the following items before installing the boiler. Universal Temperature Sensor PRV-Air Vent Adapter (with Clip) (with Clip) Installation &...

  • Page 7: Specifications

    2. Based on U.S. Department of Energy (DOE) test procedures. 3. The net AHRI water ratings shown are based on a piping and pickup allowance of 1.15. Consult Navien before selecting a boiler for installations having unusual piping and pickup requirements, such as intermittent system operation, extensive piping system, etc.
  • Page 8 General Specifications Item NFB-301C NFB-399C Dimensions 25.1 in (W) × 22.3 in (D) × 32.8 in (H) Boiler Weight 243 lb (110 kg) 278 lb (126 kg) Boiler Weight with Water 307 lb (139 kg) 371 lb (168 kg) Installation Type Indoor Wall-Hung Venting Type Forced Draft Direct Vent...

  • Page 9: Components

    1.4 Components The following diagram shows the key components of the boiler. Component assembly diagrams and particular parts lists are included in the Appendixes. Intake Air Exhaust PRV-Air Vent Connection (Optional Heating Supply) Optional Heating Return Flame Detector Igniter Fan & Motor Assembly Mixing Chamber Dual Venturi Fire-Tube Type...
  • Page 10 PRV-Air Vent Connection Optional Heating Return (Optional Heating Supply) Internal Air Filter Mixing Chamber Fan & Motor Assembly Dual Venturi Fire-Tube Type Heat Exchanger Gas Valve ASME Name Plate Air Intake Pipe Gas Pipe Terminal Block Front Panel Power Switch Heating Supply Heating Return Condensate Trap...

  • Page 11: Dimensions

    1.5 Dimensions The following diagrams show the dimensions of the boiler and the table lists the supply connections. Supply Connections Diameter Description NFB-301C NFB-399C Air Intake 3 in Exhaust Gas Vent 3 in PRV-Air Vent Connection /2 in (Optional Heating Supply) Optional Heating Return /2 in Heating Supply...
  • Page 12 Supply Connections 12.7” (320.7 mm) 16.5” (420 mm) 8.5” 5.3” (217 mm) (136 mm) 3.2” (81 mm) 4” (102.3 mm) 18.9” (480.6 mm) 18.4” (468 mm) 21” (534.2 mm) 22” (560 mm) 25.2” (640 mm) 25” (638 mm) <NFB-301C> <NFB-399C> About the Boiler...

  • Page 13: Rating Plate

    1.6 Rating Plate The Navien NFB boilers come from the factory configured for use with Natural Gas (NG). Before starting the installation, check the rating plate located on the side of the boiler to ensure that the boiler matches the gas type, gas pressure, water pressure, and electrical supply available in the installation location.

  • Page 14: Installing The Boiler

    2. Installing the Boiler 2.1 Removing the Wood Pallet from the 3. Remove the wood pallet, the upper container, and the lower pad. Boiler After you open the box, remove the wood pallet and the pallet brackets and then install the boiler. Upper Container CAUTION...

  • Page 15: Choosing An Installation Location

    5. Remove the two pallet brackets. 2.2 Choosing an Installation Location When choosing an installation location, you must ensure that the location provides adequate clearance for the boiler, adequate venting and drainage options, and sufficient access to gas, water, and electrical supplies. Carefully consider the following factors when choosing an installation location: Compliance Requirements Local, state, provincial, and national codes, laws, regulations, and...
  • Page 16 Do not install the boiler on carpeting. Navien will not be responsible for water damages that occur as a result. For more information about condensate drainage, refer to “3.2 Connecting the Condensate Drain”...

  • Page 17: Mounting The Boiler To The Wall

    2. Mount the wall bracket and the boiler following the instructions below for your installation type. CAUTION Mounting to a wood studded wall: Mount the wall bracket using the lag bolts provided. It is necessary to leave clearance for service access. Mounting to a concrete wall: Mount the wall bracket using the anchor bolts provided.
  • Page 18 WARNING The boiler is heavy. Always lift the unit with assistance. Be careful not to drop the boiler while lifting or handling it to avoid bodily injury or damage to the unit. It is recommended to use a lifting device when lifting the product. The maximum load of the device should be based on the weight of the appliance with water.

  • Page 19: Installing The System Piping

    All systems, old and new, system. Freeze protection for new or existing systems requires must be cleaned to remove flux, grease and carbon residue. Navien specially formulated glycol, which contains inhibitors to prevent recommends cleaning the boiler system with cleaning products the glycol from attacking the metallic system components.
  • Page 20 Oxygen Elimination 3.1.2 Essential Elements in a Space Heating System This boiler may only be installed in a pressurized closed-loop Boiler Piping Options heating system, free of air (oxygen) and other impurities. To avoid the presence of oxygen, ensure all of the air is removed from The following illustrations show various boiler piping options.
  • Page 21 The Navien NFB boiler comes with an air vent and an adapter bushing that must be connected to the air vent connection. The vent efficiently removes the air from the space heating system.
  • Page 22 Internal LWCO Install a backflow preventer valve in the make-up water supply to the unit as required by local codes. The Navien NFB boiler is equipped with a factory-installed, pressure-sensing type low water cutoff (LWCO) device. The Expansion Tank minimum operation pressure for this device is 6 psi by default.
  • Page 23 Pressure Relief Valve The illustration below shows an example of a pressure relief valve and an air vent installed with the PRV-air vent adapter included in To complete the space heating system installation, you must the accessory box. Use the included nipple to attach the pressure install a in pressure relief valve (up to 160 psi max.) on the space relief valve to the adapter.
  • Page 24 3.1.3 Space Heating System Piping When connecting the space heating system, follow these guidelines: Carefully tighten all connections to avoid damage to fittings. After installing the boiler, check the space heating system's operation and inspect for leaks. Pump Specifications Pump Model Model Temp.
  • Page 25 PQ Curve NFB-301C NFB-299C Q [GPM] Q [GPM] 11.5 14.5 17.0 19.0 22.0 25.0 28.0 30.0 32.5 H [ft] 11.0 12.6 NFB-399C NFB-399C Q [GPM] Q [GPM] 10.5 15.5 20.0 24.6 27.0 30.0 35.0 40.0 42.0 H [ft] Installing the System Piping...
  • Page 26 Maximum and Minimum Flow Rates through the Boiler Model Minimum Pipe Diameter Maximum Flow (GPM) Minimum Flow (GPM) NFB-301C " NFB-399C " Temperature Rise Conditions 20°F ΔT @ 100% water 25°F ΔT @ 100% water 35°F ΔT @ 100% water Model Flow Rate (GPM) Head (Ft)

  • Page 27: Connecting The Condensate Drain

    3.2 Connecting the Condensate Drain 3. Attach the clip to the condensate trap. The Navien NFB boiler creates condensation when it operates. This condensation has an acidic pH of 3-5. Follow all local codes and regulations when disposing of condensate from the boiler.
  • Page 28 Before connecting the condensate drain, choose one of the To connect the condensate drain: following disposal options: 1. Connect a drain line to the in fitting at the bottom of the boiler. Use only corrosion-resistant material for the drain line, such as PVC or CPVC.

  • Page 29: Filling The System

    If option 'b' (p. 28) is selected as the disposal option, the Navien Maintenance light commercial condensate neutralizer kit is recommended. The condensate from the appliance flows through the neutralizing Periodically monitor the level of media in the neutralizer and test media and increases the pH of the condensate.

  • Page 30: Testing The Water System

    3.3.1 Make-up Water Connection 3.4 Testing the Water System An external make-up water connection is required. The illustration below shows an example of an external water supply connected to WARNING the system piping. Ensure that the boiler is full of water before firing the burner. Operating the unit without completely filling it will damage the boiler.

  • Page 31: Considerations For System Applications

    Read and follow the guidelines listed below when installing system 3. Fill the boiler to the correct system pressure. The correct piping for the Navien NFB boiler: pressure will vary with each application. The typical cold water System application drawings are intended to explain the system fill pressure for a residential system is 12 psi.
  • Page 32 Air Handler Interface WARNING The Navien NFB boiler can control the operation of an air handler when a thermostat is used in combination with the air handling The boiler, when used in conjunction with an air conditioning unit. The Air Handler Interface is designed to stop air handler system, must be installed so that the chilled medium is operation when the boiler’s space heating function is not...
  • Page 33 3.5.2 System Application - Zone System with Pumps (Primary/Secondary Piping) Additional Zone Zone #2 Zone #1 Air Separator Return filter Pressure Relief Valve Make-up Water Air Vent Backflow preventer Pressure reducing valve Expansion Tank Air Vent Bushing Return Pressure Relief Valve Air Vent Busing Auto Air Double Nipple...
  • Page 34 3.5.3 System Application - Air Handler System Pressure Return Relief Valve Pressure Air Vent Relief Valve Air Vent Busing Auto Air Double Nipple vent Air Vent Bushing Supply <Alternate Top Connections> Return filter Air Separator Make-up Water Backflow preventer Expansion Tank Pressure reducing valve Air Flow Air Handler...
  • Page 35 3.5.4 System Application - DHW System with Indirect Tank (Primary/Secondary Piping) System Pump Air Separator Return filter Make-up Water Backflow preventer Pressure reducing valve Expansion Tank Anti-scald mixing valve Indirect Tank Boiler Pump DHW Pump DHW Inlet DHW Outlet System application drawings are intended to explain the system piping concept only. Note Install a filter in the system return to remove foreign objects from the system.

  • Page 36: Examples Of Electrical Connections

    3.6 Examples of Electrical Connections WARNING Improperly connecting the electrical supplies can result in electrical shock and electrocution. Follow all applicable electrical codes of the local authority having jurisdiction. Connecting the electrical components should be performed only by a licensed professional. CAUTION Label all wires before disconnecting them when you work on the controls.
  • Page 37 3.6.3 Wiring Diagram - Zone Pump System The NFB Boilers can operate a heating system with up to 3 zones. The following is the wiring diagram for a zone pump system with 3 zones. Without 24VAC Connections Boiler Pump Zone Pump 1 Zone Pump 2 Pump Ground Use with dry...
  • Page 38 With 24VAC Connections Boiler Pump Zone Pump 1 Zone Pump 2 Pump Ground Use with dry Thermostat 1 Thermostat 2 Thermostat 3 contacts only Zone Pump 3 If you have a 24 V thermostat, connect it to the R & C terminals on the boiler’s PCB. Note The C terminals are for optional connections with 24 V thermostat COMMON.
  • Page 39 3.6.4 Wiring Diagram - Zone Pump System with DHW Tank The NFB Boilers can operate a heating system with up to 2 zones and 1 DHW Tank. The following is the wiring diagram for a zone pump system with 2 zones and 1 DHW Tank. Without 24VAC Connections Boiler Pump DHW Aquastat...
  • Page 40 With 24VAC Connections Boiler Pump DHW Aquastat (Priority) DHW Pump Zone Pump 2 Pump Ground Use with dry Thermostat 1 Thermostat 2 Thermostat 3 contacts only Zone Pump 3 The C terminals are for optional connections with 24 V thermostat COMMON. Note If the DHW Tank is connected to the terminal, the T/S Zone 1 input is not available.
  • Page 41 Refer to the user manual that is supplied with the Navien Smartzone+ zone pump controller for details. The Navien zone controller option in the Ext Connection menu must be set to "ON. " To view the Navien zone controller setting, tap...
  • Page 42 3.6.6 Wiring Diagram - Generic Zone System with 3.6.7 Wiring Diagram - Air Handler Circulators <NFB> <NFB> Thermostat <Air Handler> <NFB> Zone1 T/S Zone2 T/S Zone3 T/S Zone4 T/S Zone5 T/S Zone6 T/S Generic Zone Controller Zone1 Pump Zone2 Pump Zone3 Pump Zone4 Pump Zone5 Pump...
  • Page 43 3.6.8 Wiring Diagram - DHW System with Indirect When connecting the DHW Tank Sensor Tank The Navien Universal Temperature sensor can be used as a DHW Tank Sensor. When installing the Universal Temperature sensor to <NFB> the boiler, follow these guidelines: This sensor is compatible for use with aquastat immersion wells.
  • Page 44 On the front panel, tap the Control button ( ) > SH Control, and select one of the SH Control Method options. Additional universal temperature sensors are available for purchase where Navien products are sold. Refer to “11.5.2 Setting the Space Heating Operation” on Page 93 for details.

  • Page 45: Connecting External Devices (Field Wiring Guidelines)

    If the Pump1 Setting menu on the SH Control menu is 3.7.5 Outdoor Temperature Sensor set to Zone1 Pump, Thermostat 1 cannot be used. Connect the Navien outdoor temperature sensor to the OUTDOOR terminal (CNT3). Also, install the sensor on the wall and avoid areas 3.7.2 DHW Thermostat...
  • Page 46 3.7.8 Auto Reset Safety Switch 3.7.13 DHW Priority Connect an external safety device, such as a louver switch or a The DHW priority provides output through the boiler controller. low gas pressure switch, to the AUTO terminal (CNC10). Only When the DHW mode is on while there is a space heating demand, external safety devices with relay output contacts are available.

  • Page 47: Connecting The Gas Supply

    This boiler cannot be converted from natural gas to propane or vice versa without a Navien gas conversion kit. Do not 5. Install certified full port valves on the gas supply line and attempt a field conversion of this boiler without a Navien gas boiler.
  • Page 48 When using rigid pipe, Navien recommends the installation of a union on the gas supply line close to the boiler, to facilitate any future maintenance or service.

  • Page 49: Gas Pipe Sizing Tables

    4.1 Gas Pipe Sizing Tables The following tables are referenced from 2012 National Fuel Gas Code for reference only. Please consult the gas pipe manufacturer for actual pipe capacities. Maximum Natural Gas Delivery Capacity In Cubic Feet (ft ) per Hour (0.60 Specific Gravity; 0.5 in WC Pressure Drop). Contact your gas supplier for BTU/ft ratings.

  • Page 50: Measuring The Inlet Gas Pressure

    Maximum Liquefied Propane Delivery Capacity In Thousands of BTU/H (0.5 in WC pressure drop) Length (including fittings) Pipe Size 10 ft 20 ft 30 ft 40 ft 50 ft 60 ft 80 ft 100 ft 125 ft 150 ft 175 ft 200 ft 250 ft (3 m)
  • Page 51 To measure the inlet gas pressure: 8. Loosen the screws indicated in the figure below and connect a manometer to the pressure port. Reset the manometer to zero 1. Shut off the manual gas valve on the gas supply line. before use.

  • Page 52: Venting The Boiler

    5. Venting the Boiler Connecting the Pipe to the Vent Collar WARNING 1. Measure 3-1/8” inches from the end of the vent pipe, then draw a mark at that distance. Improper venting of the boiler can result in excessive levels of carbon monoxide, which can lead to severe personal injury or death.
  • Page 53 CAUTION DANGER Do not start the vent run with a street elbow at the vent If the connections leak, harmful flue gas may cause personal collar. Using an elbow directly at the collar will not allow for a injury or death. After completing the installation and filling the tight seal between the appliances and vent pipe.

  • Page 54: Selecting A Vent Type

    If you cannot use a direct vent, ensure that an ample supply of make-up air is available in the installation location. Navien also recommends installing a new vent system with this appliance. If reusing an existing vent system, thoroughly inspect it for punctures, cracks, or blockages prior to connecting it to the boiler.
  • Page 55 75 in 100 in will not be covered by the Navien warranty. If there is any question about the possibility of back drafting in the installation location, A minimum free area of 1 in Outside air from 2 use a direct venting system for the boiler.
  • Page 56 Canadian Non-Direct Vent US Non-Direct Vent Description Installations Installations Clearance above grade, veranda, porch, deck, or balcony 12 in (30 cm) 12 in (30 cm) 48 in (120 cm) below or to side Clearance to window or door that may be opened 36 in (91 cm) of opening;...

  • Page 57: Selecting Vent Pipe Materials

    5.2 Selecting Vent Pipe Materials This product is set to use PVC as the default vent pipe material. If you require that return water hotter than 140°F (60°C) to circulate back to boiler, the DIP switch must be configured (DIP Switch 2, Venting requirements differ in the US and Canada.

  • Page 58: Measuring Vent Length

    5.3 Measuring Vent Length The following polypropylene vent components are approved for use as terminations: The maximum vent length when using 3 in exhaust ducts is 60 ft Duravent PolyPro® (18 m). The maximum vent length when using 4 in vent ducts 3PPS-E90L or 4PPS-E90L (3”...
  • Page 59 Indoor Boiler Installation Venting Examples For cascade applications, the required horizontal Note clearance between terminations is 12” for both sidewall The following are some possible indoor venting options: and vertical venting installations. Multiple Vent / Air Terminations Do not vertically stack 12”...
  • Page 60 Indoor Boiler Installation Venting Examples (continued) Indoor Boiler Installation Venting Examples (continued) Non-Concentric Sidewall Venting - Air is drawn from a different 3 in or 4 in Two-pipe Vertical Venting – Intake and exhaust pipes location that is at least 12 in (300 mm) away from the exhaust do not have to terminate in the same area.

  • Page 61: Removing The Internal Air Filter

    Flexible Vent Systems (Polypropylene) 5.5 Removing the Internal Air Filter The NFB boiler is equipped with an internal air filter to remove dust and debris that accumulate inside the boiler. The dust and debris accumulated inside the boiler should be removed from the internal air filter every two years.
  • Page 62 3. Remove the filter from the boiler and replace with a new filter. One Replacement filter is included. Additional filters Note can be ordered through authorized Navien distributors. CAUTION If the air filter is not replaced, it may result in poor performance for the boiler.

  • Page 63: Setting The Dip Switches

    6. Setting the DIP Switches 6.2 DIP Switch 2 (8 switch unit) CAUTION The DIP SW 2 on the circuit board configures the gas type, country, and enables or disables the space heating thermostat. Do not remove the front cover unless the power to the boiler is turned off or disconnected.

  • Page 64: Connecting The Power Supply

    7. Connecting the Power Supply We recommend using a surge protector to protect the boiler from power surges. WARNING If there is a power failure in cold weather areas, the freeze prevention system in the boiler will not operate and may result Improperly connecting the power supply can result in electrical in the heat exchanger freezing.

  • Page 65: Installing A Cascade System

    Use pumps with integral check valves or install check valves at the pump outlets. Navien universal temperature sensors (#GXXX001769) must be installed for cascade system operation. Adjust the settings at the main unit as the cascade system uses only the main unit settings. Changes made to the sub units are ignored.
  • Page 66 System Application #1- Cascade System with Closely Spaced Tees Main Sub1 Sub2 Supply Air separator Cold water Back flow preventor Expansion tank Temperature 12” (30 cm) sensors (required) maximum Return Connect the “SH Demand (SH T/T or Zone controller)” to the main unit. Note Connect the universal temperature sensors to SUPPLY and RETURN terminals of the CNT1/CNT2 terminal strip on the main unit PCB.
  • Page 67 System Application #2- Cascade System with Hydro Separator Supply Sub2 Main Sub1 Return Temperature sensors (required) Dirt collector Cold water Hydro/Air separator Back flow preventor Expansion tank Connect the “SH Demand (SH T/T or Zone controller)” to the main unit. Note Connect the universal temperature sensors to SUPPLY and RETURN terminals of the CNT1/CNT2 terminal strip on the main unit PCB.
  • Page 68 System Application #3 - Cascade System with Zone Pump Control Supply Supply Supply Sub2 Main Sub1 Return Return Return Temperature sensors (required) Dirt collector Cold water Hydro/Air separator Back flow preventor Expansion tank Note Both the main unit and sub units use zone pumps for this application. To enable this feature, tap the Control button ( ) >...
  • Page 69 System Application #4 - Cascade System with DHW Indirect Tank Air separator Supply Cold water Back flow preventor Expansion tank Sub1 Sub2 Main Indirect tank Aquastat Temperature 12” (30 cm) sensors (required) maximum Return Cold water Connect the aquastat on the DHW indirect tank to the main unit. Note Connect the DHW pump to the main unit.
  • Page 70 System Application #6- Cascade System with DHW Indirect Tank (for Low DHW Demand) Supply Main Sub1 Sub2 Indirect Air separator tank Cold water Back flow preventor Expansion tank Aquastat 12” 30 cm Temperature maximum sensors (required) Return Cold water In this configuration, space heating and DHW can operate simultaneously. Note The aquastat on the DHW indirect tank must be connected to a sub unit.

  • Page 71: Connecting The Communication Cables

    8.2 Connecting the Communication Cables When configuring a cascade system, consider the following pipe Up to 32 boilers can be connected with Navien Ready-Link diameters and flow rates. Note that flow rates above 4 ft/s may communication cables. Select one of the boilers in the cascade cause pipe erosion or velocity noise.

  • Page 72: Installing A Common Vent System

    The Navien Common Vent System* provides an easy way to install the “Included Items” on page 77). the vent system for up to 4 Navien NFB Boiler units. By sharing the main intake and exhaust vent pipes, effective system venting...
  • Page 73 Adequate Installation Clearances Clean, Debris and Chemical-Free Combustion Air Do not install the boiler in areas where dust and debris may accumulate or where hair sprays, spray detergents, chlorine, or CAUTION similar chemicals are used. Do not install the boiler in areas where gasoline or other Do not install the boiler on carpeting.
  • Page 74 General and Local Standards Information Cutting and Assembling Common Vent System Components When installing and operating the common vent system, the following standards and regulations must be complied with and Standard tools are suitable for the cutting and assembly of adhered to: common vent system components.
  • Page 75 Vent Pipe Pitch and Supports 3. Hold the pipe and pipe fitting together for about 15 seconds until the cement sets. For horizontal runs, slope the horizontal section upward toward Use approved solvent type cement for the proper Note the vent termination at a rate of ”...
  • Page 76 9.1.2 Determining the Length of a Common Common Vent Length Table [Total Length (L) = Vent System W + H] Follow the instructions listed below to determine the length of a Vent Length for NFB Boiler Units common vent. 1. Add the BTU/H input ratings for each unit in the cascading Required Model Total Length (ft)

  • Page 77: Navien Backflow Damper (Back-Draft Damper)

    9.2 Navien Backflow Damper (Back-draft Maintenance Port Damper) Navien Backflow Damper has a maintenance port to allow you to easily inspect the operating condition of the damper plate. The Navien backflow damper prevents backflow (back-draft) at the exhaust vent while the boiler unit operates.

  • Page 78: Starting The Common Vent System

    9.3 Starting the Common Vent System 3. Connect the backflow damper to the exhaust duct of the boiler unit. 9.3.1 Backflow Damper Assembly Follow the instructions below to assemble the backflow damper on the NFB boiler unit: 1. Remove the screws from the exhaust vent adapter. 4.
  • Page 79 9.3.2 Connecting the Pipe to the Damper 3. Tighten the clamp with a screwdriver to properly seal the joint. 1. Measure 3-1/8” from the end of the vent pipe, then draw a mark at that distance. Mark 3-1/8” from the end of the pipe 3-1/8”...
  • Page 80 9.3.3 Assembling the Wye Joint 2. Assemble the wye joint or wye assembly to the vent pipe. Apply solvent cement to the mating surfaces. 1. Assemble the hub wye, the 8” to 3” reducer, and the 90º elbow into the common vent. You can also use the hub reducing wye and the 90º...

  • Page 81: Connecting And Terminating The Vent Pipe

    9.4 Connecting and Terminating the Vent Pipe Refer to the following example to install the common vent system. The installation area should be measured to ensure that sufficient space is available to install the boiler units and the common vent system. Ensure that the common vent system is installed near the boiler units while satisfying all clearance requirements that are specified in this manual as well as the Installation Manuals supplied with the boiler units.

  • Page 82: Setting Up The Common Vent System

    9.5 Setting up the Common Vent System 9.6 Common Vent Termination Clearances DANGER 9.6.1 Direct Vent Application – Vertical Installation Incorrect settings may lead to severe personal injury, death, or property damage. 36” min. Exhaust Refer to the following figures when setting the common vent type. 1.
  • Page 83 9.6.3 Direct Vent Application – Horizontal The illustration is intended for reference purposes Note only. Installation Direct the exhaust away from any building openings. During cold weather situations, the temperature of the exhaust will be much warmer than the ambient air.

  • Page 84: Installing A Condensate Drain

    9.7 Installing a Condensate Drain To install a condensate drain to the cascade system: 1. Form a loop with a drain hose and fix it with a tie. Refer to the following examples to install a condensate drain hose (field supplied) to the common vent system. The condensate While shaping the hose, do not bend the hose Note drain hose prevents condensate or rain from entering the exhaust...

  • Page 85: Exhaust Vent Termination Clearances (For Direct Vent)

    9.8 Exhaust Vent Termination Clearances (For Direct Vent) Description Canadian Direct Vent Installations1 U.S. Direct Vent Installations2 Clearance above grade, veranda, porch, deck, or 12 in (30 cm) 12 in (30 cm) balcony Clearance to window or door that may be opened 36 in (91 cm) 12 in (30 cm) Clearance to permanently closed window...

  • Page 86: Maintenance

    9.9 Maintenance 3. Reinstall the gasket and maintenance port cover, and then fix them with a set screw. Periodically check the damper condition inside the backflow damper through the maintenance port to ensure optimal performance of the system. Follow the instructions to check the damper condition and replace the backflow damper if necessary.

  • Page 87: Installation Checklist

    To troubleshoot any operational problems refer to “Troubleshooting” in the Owner’s Manual. If you have additional questions or need assistance with installation, contact Technical Support at 1-800-519-8794 or 1-949-420-0420, or refer to the technical support section of Navien’s website (www.navien.com). Installing the boiler...
  • Page 88 Connecting a Pressure Relief Valve Have you installed an approved pressure relief valve on the boiler? Does the rating of the pressure relief valve match or exceed the maximum BTU rating of the boiler? Is the pressure relief valve in on the space heating outlet? Have you installed the pressure relief valve on the space heating supply pipe near the boiler? Have you installed a discharge drain tube from the pressure relief valve to within 6-12 in (150-300 mm) of the floor? Connecting the Condensate Drain...
  • Page 89 PCB DIP SW 2 setting (Set of 8) Is switch #1 set correctly for the gas type used? (NG-OFF, LP-ON) If continuous boiler operation is required, is switch #7 in the up (ON) position? If high temperature venting has been installed (CPVC or polypropylene), is switch #8 in the up (ON) position? Operating the boiler Have you given the Installation &...

  • Page 90: Operating The Boiler

    11. Operating the Boiler 11.1 Turning the Boiler on or off 11.1.1 Turning the Space Heating On or Off To turn the Space Heating on or off, tap SH ON on the top left of To turn the boiler on: the screen.

  • Page 91: Adjusting The Temperature

    11.2 Adjusting the Temperature 11.2.2 Adjusting the DHW Indirect Supply Temperature To adjust the water temperature on the screen, tap 11.2.1 Adjusting the Space Heating Temperature select the DHW Indirect Supply temperature in the DHW Set Temp menu. The current temperature setting is displayed in the menu. To adjust the heating temperature on the screen, tap to select the space heating temperature in the SH Set Temp menu.

  • Page 92: About The Operating Status Information

    11.3 About the Operating Status 11.4 Resetting the Boiler Information If an error message appears during boiler operation, reset the boiler to resolve the problem. Press and hold the Reset button on The following table provides detailed information for the operating the front panel to reset the boiler.
  • Page 93 11.5.1 Viewing Basic Information 11.5.2 Setting the Space Heating Operation To view information about the boiler, tap the Control button ( To set the boiler’s space heating operation, tap the Control button > Status on the screen. ) > SH Control on the screen. Tap an item to view the information.
  • Page 94 Priority Set. This function is disabled automatically if Outdoor Reset, BMS Set space heating target temperature (°C). Status, and Navien zone controller are enabled. Supply set temperature In cascade mode, two types of space heating modes are available - Setting range: depending on the settings for the Zone Setting menu.
  • Page 95 11.5.3 Setting the DHW Operation (Indirect) Item Description Select the outdoor reset load. To set the boiler’s indirect DHW operation, tap the Control button 4. Curve select ) > DHW Control on the screen. Default: Finned Tube Baseboard Enable or disable the Warm Weather Shut Down temperature function.
  • Page 96 * This function will provide protection from growth of legionella 11.5.5 Viewing Other System Information bacteria in the DHW tank only. It will not protect water supply piping. To view the miscellaneous system information, tap the EMS button ) > EMS Info on the screen. A mixing valve must be installed on the DHW supply line when this mode is enabled as water temperatures will exceed 140°F (60°C).
  • Page 97 11.5.6 Setting General Building Management Setting Detailed Building Management System (BMS) information System (BMS) Information The boiler’s firing rate and set point can be controlled by 0 – 10 V Building Management System (BMS) input, if BMS Status is set To set the general Building Management System (BMS) to Enabled.
  • Page 98 11.5.8 Setting General Options Item Description Set the BMS off differential voltage. To set up general options, tap the Set button ( ) > General on Boiler stops operating when the input the screen. differential voltage is lower than the set 7.

  • Page 99: Accessing Advanced Menu Items

    11.6 Accessing Advanced Menu Items Tap ( ) to go to the next page. 11.6.1 Viewing Service Information To view service information about the boiler: 1. Tap the Set button ( ) > Service. Item Description Set the date and time by tapping 1.
  • Page 100 Item Description Item Description 8. Δ T Limit - No. of Number of times supply return 1. SH1 Thermostat Space heating thermostat 1 input times temperature limit control has activated Input status 9. Supply Limit - No. Number of times Recirculation supply 2.
  • Page 101 11.6.3 Setting the Operation Parameters Item Description To set the boiler’s operation parameters, tap the Set button ( ) > Set the space heating supply minimum Parameter on the screen. temperature. 1. Supply Absolute Setting range: 77°F (25°C) – [MAX MIN Set-point Set-point –...
  • Page 102 Item Description Item Description Set the time to reach the maximum Set the SH pump over-run time. space heating capacity after initial 19. Boiler Pump Delay Setting range: ON/OFF 10. Burning operation. Default: OFF Acceleration Time Setting range: 0 – 20 min Set the DHW On temperature when Default: 3 min using the DHW temperature sensor.
  • Page 103 11.6.4 Configuring a Cascade System Item Description To view and configure the cascade settings, tap the Set button Select this option on the main unit ) > Cascade on the screen. of a cascade system to end cascade operation. Enter main setting mode to reassign IDs and begin a cascade system 2.
  • Page 104 Item Description Item Description Set the heating capacity standard when Set Force Lead Change. removing the boilers for the cascade Yes: Reassign the lead boiler system. (Applied if Operation Strategy regardless of the demand status. 3. Force Lead Change is set to Custom.) 3.
  • Page 105 Setting the Operation Strategy To set the operation strategy (operating algorithm), select the strategy from Comfort (default), Eco, or Boost. The detailed information for each mode is as follows. Comfort Boost Custom Unit On HC: The value of Late On/Early Off Early On/Late Off Late On/Early Off Unit On HC...
  • Page 106 This mode increases the condensing effectiveness and quickly responds to a large amount of load changes. However, it requires additional unit operation time (Low Off HC) and sensitively responds to a small amount of load changes (Small On/Off gap). 47.5% 47.5% Unit ON Unit ON...
  • Page 107 Setting range: ON/OFF Tap ON or OFF to toggle the fan test Default: OFF (ON -> OFF / OFF -> ON). Turn on or turn off the Navien zone Test the boiler pump operation. controller. 2. Navien zone The boiler pump is turned on as soon...
  • Page 108 11.6.7 Setting the Operation Modes 11.6.8 Operating in Air Purge Mode To operate the boiler in special operation modes: To operate the boiler in air purge mode: 1. Tap the Set button ( ) > Service. 1. Tap the Set button ( ) >...

  • Page 109: Understanding Error Codes

    11.7 Understanding Error Codes When an error code appears on the front panel, refer to the following chart for a definition and possible remedy for the situation. Error Code Reason Self-diagnostic/Action E001 Heat exchanger over temperature Auto reset/Manual reset/Power On reset E003 Ignition failure Manual reset/Power On reset...

  • Page 110: Appendixes

    WARNING 1STEP-ORIFICE 1STEP-ORIFICE NG : 6.75 NG,H : 7.40 : 5.4 : 5.4 20046179A This conversion kit must be installed by a qualified service agency* in accordance with Navien’s instructions and all Orifice NFB-301C NFB-399C NFB-301C NFB-301C 1STEP-ORIFICE 2STEP-ORIFICE 2STEP-ORIFICE...
  • Page 111 Procedure: 5. Remove the clip at location A – the connection above the gas valve where it connects to the gas valve outlet adapter. See Figure 3 for reference. 1. Turn off both gas and water supply to the boiler. 6.
  • Page 112 Attempting to alter or measure the gas valve outlet pressure personal injury or death. could result in damage to the valve, causing potential severe personal injury, death or substantial property damage. Navien NFB boilers are shipped ready to fire natural gas ONLY. Figure 6. Orifice Identification Packing...
  • Page 113 10. Set the PCB DIP switch to change the gas type. For LP, set DIP switch 2 #1 to ON. For NG, set DIP SW2 #1 to OFF. DANGER When conversion is required, be sure to set the PCB DIP WARNING switch 2 #1 according to the supply gas type.
  • Page 114 12. Measure and adjust the gas/air ratio. c. Activate multiple zones and set the boiler to operate at 1Step MIN mode. Option 1. Using Combustion Analyzer (recommended) a. Loosen the screw, rotate the plate and remove the gasket For operation mode selection, refer to “11.6.7 Note to access the emissions monitoring port as shown in Setting the Operation Modes”...
  • Page 115 Option 2. Using Digital Manometer <NFB-301C> <NFB-399C> a. Open the offset pressure port by loosening the screw two turns as shown in Figure 9. <NFB-301C> <NFB-399C> Figure 10. Set Screw Location Digital pressure The set screw is located behind the screw-on cover. Note manometer This must be removed first.

  • Page 116: Wiring Diagram

    12.2 Wiring Diagram T/S INPUT AC24V T/S INPUT AC24V T/S INPUT AC24V T/S INPUT AC24V 116 Appendixes...

  • Page 117: Ladder Diagram

    12.3 Ladder Diagram AC INPUT(AC 120V) AC INPUT(AC 120 V) LIVE NEUTRAL LIVE NEUTRAL Terminal Board Relay 1 Boiler Pump Relay 2 ZONE1 Pump Dual Venturi Relay 3 Relay 5 FILTER ZONE2 Pump Relay 6 Relay 4 Igniter Relay 7 ZONE3 Pump Blower Primary...

  • Page 118: Outdoor Temperature Sensor

    When necessary, shielded cable may be used. Make sure wiring connections are secure before closing the cap. The sensor is a water resistant device. Any damage to the device may require the replacement of the entire component. Navien Outdoor Temperature Sensor Kit 118 Appendixes...

  • Page 119: Outdoor Reset Control

    12.5 Outdoor Reset Control Outdoor Temperature Sensor Installation Guidelines The Outdoor Reset Control feature may be used to enhance energy Supply Set Point Return Set Point efficiency while maintaining optimal heating performance. With Heat Load Range Range the Outdoor Reset Control, the space heating temperature setting automatically changes according to the outdoor temperature and Finned Tube 120-180°F...

  • Page 120: Component Assembly Diagrams And Part Lists

    12.6 Component Assembly Diagrams and Part Lists 12.6.1 Case Assembly - NFB-301C 120 Appendixes...
  • Page 121 Description Part # Remark Case Upper 20042573A (SET) Case Upper 30023701A NFB-301C SERVICE KIT Case Middle 20042572A Case Lower 20042571A (SET) Case Lower 30023702A NFB-301C SERVICE KIT Cover 30020590A (SET)Cover 30023383A NFB-301C SERVICE KIT Main PCB 30020431A Terminal PCB 30020433A Front Panel 30019786A Exhaust Duct Assembly...
  • Page 122 12.6.2 Case Assembly - NFB-399C 122 Appendixes...
  • Page 123 Description Part # Remark Case Upper 20042659A (SET) Case Upper 30023699A NFB-399C SERVICE KIT Case Middle 20042521A Case Lower 20042517A (SET) Case Lower 30023700A NFB-399C SERVICE KIT Cover 30020590A (SET)Cover 30023383A NFB-399C SERVICE KIT Main PCB 30020431A Terminal PCB 30020433A Front Panel 30019786A Exhaust Duct Assembly...
  • Page 124 12.6.3 Heat Exchanger and Waterway Assembly - NFB-301C 124 Appendixes...
  • Page 125 Description Part # Remark Heat Exchanger Assembly 30021565A (SET) Heat Exchanger Assembly 30023358A NFB-301C SERVICE KIT Drain Pan Assembly 30020747A Supply Pipe (Upper) 30020985A Packing 20041401A Heat Exchanger Outlet Adapter 30021367A Supply Pipe (Lower) 30020986A Fastener 20040255A Supply/Return Pipe (Lower) Adapter 20040244A LWCO (Pressure sensor) 30022672A...
  • Page 126 12.6.4 Heat Exchanger and Waterway Assembly - NFB-399C 126 Appendixes...
  • Page 127 Description Part # Remark Heat Exchanger Assembly 30021566A (SET) Heat Exchanger Assembly 30023357A NFB-399C SERVICE KIT Drain Pan Assembly 30020580A Supply Pipe (Upper) 30020996A Packing 20043332A Heat Exchanger Outlet Adapter 20043652A Supply Pipe (Lower) 30020596A Fastener 20040255A Supply/Return Pipe (Lower) Adapter 20043268A LWCO (Pressure sensor) 30022672A...
  • Page 128 12.6.5 Combustion Parts Assembly - NFB-301C 128 Appendixes...
  • Page 129 Description Part # Remark Fan Assembly 30020992A Fan Packing 20043751A Fan Adapter 20043334A Fan Adapter Packing 20043335A Dual Venturi 30020804A (SET) Dual Venturi 30023381A NFB-301C SERVICE KIT Orifice Packing 20042788A 20043012A NFB-301C (NG) 1 Stage Gas Orifice 20043013A NFB-301C (LP, High Altitude Nozzle)) 20046179A NFB-301C (NG, High Altitude Nozzle) 20043014A...
  • Page 130 Description Part # Remark Burner Packing 20042913A Burner 30022740A Ignition Transformer 30019980A Ignition Transformer Bracket 20041154A Igniter Packing 20045644A Flame Rod Packing 20045645A Flame Rod 30020805A Igniter 30020521A Flame Inspection Window (Upper) 20040231A Flame Inspection Window (Lower) 20040232A Flame Inspection Window (Graphite Packing) 20043399B Flame Inspection Window (Glass) 20040236A...
  • Page 131 12.6.6 Combustion Parts Assembly - NFB-399C Appendixes...
  • Page 132 Description Part # Remark Fan Assembly 30020992A Fan Packing 20043751A Fan Adapter 20043334A Fan Adapter Packing 20043335A Dual Venturi 30020801A (SET) Dual Venturi 30023380A NFB-399C SERVICE KIT Orifice Packing 20042788A 20042789A NFB-399C (NG) 1 Stage Gas Orifice 20044123A NFB-399C (LP, High Altitude Nozzle) 20046182A NFB-399C (NG, High Altitude Nozzle) 20042790A...
  • Page 133 Description Part # Remark Packing (Graphite) 20040234A Burner Packing 20042657A Burner 30022741A Ignition Transformer 30019980A Ignition Transformer Bracket 20041154A Igniter Packing 20045644A Flame Rod Packing 20045645A Flame Rod 30020583A Igniter 30020582A Flame Inspection Window (Upper) 20040231A Flame Inspection Window (Lower) 20040232A Flame Inspection Window (Graphite Packing) 20043399B...
  • Page 134 Memo...
  • Page 135 Getting Service If your boiler requires service, you have several options for getting service: Contact Technical Support at 1-800-519-8794 or on the website: www.navien.com. For warranty service, always contact Technical Support first. Contact the technician or professional who installed your boiler.

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