Navien NCB-190/060H User manual

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.
H
NSF/ANSI 372
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.
Installation & Operation Manual
NCB-H Condensing Combi-Boilers
Model NCB-190/060H
NCB-190/080H
NCB-240/110H
NCB-240/130H
NCB-250/150H

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 be satisfied:
1. INSTALLATION OF CARBON MONOXIDE DETECTORS. No installation or replacement of a vented gas appliance
shall be permitted unless a battery powered or electrically hard wired carbon monoxide detector is present
on the same floor as the appliance or on the next adjacent floor when the appliance is located in a crawl
space unless the appliance is located in a detached, uninhabitable garage. For all residential dwellings, a
carbon monoxide detector must also be present on each habitable level of the dwelling. These requirements
shall not be deemed to waive any additional requirements imposed by M.G.L. c. 148 §26F1/2.
2. APPROVED CARBON MONOXIDE DETECTORS. Each carbon monoxide detector as required in accordance
with the above provisions shall comply with NFPA 720 and be ANSI/UL 2034 listed and IAS certified.
3. SIGNAGE. Whenever any through-the-wall vent is installed less than seven feet above the finished grade,
a metal or plastic identification plate shall be permanently mounted to the exterior of the building at a
minimum height of eight feet above grade directly in line with the exhaust vent terminal. The sign shall
read, in print size no less than 0.5 inches in size,“GAS VENT DIRECTLY BELOW. KEEP CLEAR OF ALL
OBSTRUCTIONS”.
4. INSPECTION. The state or local gas inspector of the side wall horizontally vented gas fueled equipment shall
not approve the installation unless, upon inspection, the inspector observes carbon monoxide detectors and
signage installed in accordance with the provisions of 248 CMR 5.09 and 5.12.

3Contents
7. Connecting the Power Supply 74
8. Installing a Cascade System 75
8.1 Connecting Water Supplies 75
8.2 Cascade System - Recirculation System
Application Example 78
8.3 Connecting the Communication Cables 80
9. Installing a Common Vent System 82
9.1 About the Common Vent System 82
9.2 Navien Common Vent Collar Kit (Back-
draft Damper) 87
9.3 Starting the Common Vent System 88
9.4 Connecting and Terminating the Vent
Pipe 91
9.5 Setting Up the Common Vent System 92
9.6 Common Vent Termination Clearances 92
9.7 Installing a Condensate Drain 93
9.8 Exhaust Vent Termination Clearances (For
Direct Vent) 95
9.9 Maintenance 97
10. Installation Checklist 98
11. Operating the Boiler 101
11.1 Operating the Boiler for the First Time 101
11.2 Turning the Boiler On or Off 102
11.3 Start-Up Wizard 103
11.4 Adjusting the Temperature 103
11.5 Accessing Basic Menu Items 105
11.6 Accessing Advanced Menu Items 112
11.7 Understanding Error Codes 121
12. Appendixes 123
12.1 Gas & High Altitude Conversion 123
12.2 Wiring Diagram 131
12.3 Ladder Diagram 132
12.4 Outdoor Temperature Sensor 133
12.5 Outdoor Reset Control 133
12.6 Component Assembly Diagrams and
Parts Lists 135
1. About the Boiler 7
1.1 Included Items 7
1.2 Accessories 7
1.3 Specifications 8
1.4 Components 11
1.5 Dimensions 13
1.6 Rating Plate 14
2. Installing the Boiler 15
2.1 Choosing an Installation Location 15
2.2 Mounting the Boiler to the Wall 17
3. Installing the System Piping 19
3.1 Installing a Space Heating System 19
3.2 Installing a Domestic Hot Water (DHW)
System 23
3.3 Connecting the Condensate Drain 26
3.4 Filling the System 29
3.5 Testing the Water System 30
3.6 Considerations for System Applications 31
3.7 Examples of Electrical Connections 40
4. Connecting the Gas Supply 51
4.1 Gas Pipe Sizing Tables 54
4.2 Measuring the Inlet Gas Pressure 55
5. Venting for Combustion Air 57
5.1 Venting the Boiler 58
5.2 About the Vent Installation Detector 60
5.3 Selecting a Vent Type 62
5.4 Selecting Vent Pipe Materials 66
5.5 Measuring Vent Length 67
5.6 Terminating the Vent 68
6. Setting the DIP Switches 72
6.1 DIP Switch 1 (6 switch unit) 72
6.2 Dip Switch 2 (8 switch unit) 72
Contents

4Safety Information
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.
DANGER
Indicates an imminently hazardous situation
which, if not avoided, could result in severe
injury or death.
WARNING
Indicates a potentially hazardous situation
which, if not avoided, could result in injury or
death.
CAUTION
Indicates a potentially hazardous situation that,
if not avoided, could result in property damage.
DANGER
If you smell gas:
●Do not try to light any appliance.
●Do not touch any electrical switches or use
landline phones.
●From a neighbor’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 authorized
by your gas supplier or the fire department.
Do not use or store flammable products,
such as gasoline, solvents, or adhesives in
the same room or area as the boiler.
●The boiler has a main burner flame that can
turn on at any time and can ignite flammable
vapors. Vapors from flammable liquids can
explode and catch fire, causing death or
severe burns.
●Vapors cannot be seen and are heavier than
air. They can travel long distances along the
ground and can be carried from other rooms
to the boiler’s main burner flame by air
current.
●Keep all flammable products far away from
the boiler and store them in approved
containers. Keep the containers closed tightly
and out of the reach of children and pets.
Safety Information

5Safety Information
CAUTION
●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.
Failure to do so may result in electric shock.
●When servicing the controls, label all wires
prior to disconnecting them.
Failure to do so may result in wiring errors,
which can lead to improper or dangerous
operation. Verify proper operation after
servicing.
●Do not use unapproved replacement or
accessory parts.
Doing so may result in improper or dangerous
operation and will void the manufacturer’s
warranty.
●Do not place anything in or around the
vent terminals, such as a clothes line, that
could obstruct the air flow in or out of the
boiler.
●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.
WARNING
●Do not store or use gasoline or other
flammable liquids near this boiler.
Doing so may result in fire or explosion.
●Do not place combustibles, such as
newspapers or laundry, near the boiler or
venting system.
Doing so may result in a fire.
●Do not place or use hair sprays, spray
paints, or any other compressed gases near
the boiler or venting system, including the
vent termination.
Doing so may result in fire or explosion.
●Do not operate the boiler with the front
cover opened.
Doing so may result in fire or carbon
monoxide (CO) poisoning, which may result
in property damage, personal injury, or death.
●Do not operate this boiler without proper
venting.
Doing so may result in fire or carbon
monoxide (CO) poisoning, which may result
in property damage, personal injury, or death.
●Do not touch the power cord or internal
components of the boiler with wet hands.
Doing so may result in electric shock.
California law requires the following Prop 65
warning to be provided:
WARNING
Cancer and Reproductive Harm -
www.P65Warnings.ca.gov

6Safety Information
DANGER
This boiler’s DHW temperature is set to 120°F
(49°C) at the factory for your safety and comfort.
Increasing the temperature increases the risk of
accidental scalding. Water temperatures at or
above 125°F (52°C) can cause instant scalding,
severe burns, or death. Before you decide
to change the temperature setting, read the
following charts carefully.
Water
Temperature
Time in which a young child
can suffer a full thickness
(3rd degree) burn
160°F (70°C) Less than 1 second
140°F (60°C) 1 second
130°F (55°C) 10 seconds
120°F (49°C) 10 minutes
100°F (37°C) very low scald risk
DANGER
HOT
BURN
To prevent burns:
●Use the lowest operating temperature setting
necessary to provide comfortably-hot water.
●If your household has children or elderly or
disabled residents, consider using a lower
temperature setting.
●Do not leave children, the elderly, or disabled
persons unsupervised.
●Do not allow small children to play
unsupervised in the bathroom.
●Do not allow anyone to change the water
temperature while hot water is running.
●Read all the instructions in this manual
carefully before changing the temperature
setting.
●Feel the water before using it on children, the
elderly, or the disabled.
●If it is necessary to set the water temperature
above 125°F (52°C), consider installing a
thermostatically-controlled mixing valve
or temperature-limiting valve. Contact a
licensed plumber or your local plumbing
authority for more information.

7About 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.
Installation & Operation
Manual, User’s
Information Manual
Quick Installation Manual
2 in Vent Termination
Caps (x2) 2 in Wall Flanges (x4)
Wall Mounting Bracket Tapping Screws &
Anchors (x4)
Pressure Relief Valve,
Heating Propane Conversion Kit*
Outdoor Temperature
Sensor and Cable Spare Parts
High Altitude Conversion
Kit (Natural Gas Only)*
* High Altitude Conversion kit and Propane Conversion kit
are attached to the inside of Product’s case.
1.2 Accessories
The following optional accessories are available for
the boiler.
Condensate
Neutralizer Kit
Zone Controller
(FMZ-40/60)
Zone Controller
(FMZ-20/30)
Universal Temperature
Sensor (with clip)
Navi-Link
(Wi-Fi Control System) Ready-Link Rack
Navien Manifold System NaviClean
HotButton Push Button HotButton Wall Plate
Note The Universal Temperature Sensor can
be used as a System Temperature Sensor
or a DHW Tank Sensor.
1. About the Boiler

8About the Boiler
1.3 Specifications
The following tables list the specifications for the boiler. Additional specifications for water, gas, electricity, and
vent connections are provided in the Installation section.
Space Heating Specifications
Navien Condensing Boiler
Space Heating Ratings Other Specifications
Model Number
1
Heating Input
(MBH) Heating
Capacity
2
(MBH)
Net AHRI
Rating Water
3
(MBH)
AFUE
2
(%) Water
Pressure
Water
Connection Size
(Supply, Return)
Min Max
NCB-190/060H 11 60 56 49 95.0
12-30 psi 1 in NPT
NCB-190/080H 11 80 74 64 95.0
NCB-240/110H 13 110 102 89 95.0
NCB-240/130H 13 130 120 104 95.0
NCB-250/150H 14 150 138 120 95.0
Note 1. Ratings are the same for natural gas models converted to propane use.
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.
Domestic Hot Water Specifications
Item NCB-
190/060H
NCB-
190/080H
NCB-
240/110H
NCB-
240/130H
NCB-
250/150H
Input Ratings Min 10,700 10,700 13,300 13,300 14,000
Max 160,000 160,000 199,900 199,900 210,000
Water Pressure 15-150 psi
Minimum Flow Rate 0.5 GPM (1.9 L/m)
Flow Rate
(DHW)
35°F (19°C)
Temp Rise
8.2 GPM
(31.1 L/m)
10.4 GPM
(39.5 L/m)
10.8 GPM
(40.9 L/m)
45°F (25°C)
Temp Rise
6.4 GPM
(24.2 L/m)
7.9 GPM
(30 L/m)
8.4 GPM
(31.8 L/m)
67°F (37°C)
Temp Rise
4.3 GPM
(16.2 L/m)
5.4 GPM
(20.3 L/m)
5.6 GPM
(21.2 L/m)
77°F (43°C)
Temp Rise
3.7 GPM
(14.0 L/m)
4.7 GPM
(17.8 L/m)
4.9 GPM
(18.5 L/m)
DHW Supply Connection Size 3/4 in NPT
Cold Water Input Connection
Size 3/4 in NPT

9About the Boiler
NCB-H Internal Pump
The NCB-H boiler is equipped with an internal circulation pump. The following table provides detailed
information on the pump used for the boiler and the performance curve.
Item Pump Model
NCB-190/060H, NCB-190/080H,
NCB-240/110H, NCB-240/130H, NCB-250/150H
Internal Circulation Pump
Grundfos UPS 15-78 CIAO2
(Part Number: 30023987A)
0
5
10
15
20
25
30
35
40
0
2
4
6
8
10
12
14
16
18
20
0 2 4 6 8 10 12 14 16
FT of Head
△P (psi)
Flow Rate (GPM)
NFC Flow Performance Curve
NCB-250/150H
NCB-240/130H
NCB-240/110H
NCB-190/080H
NCB-190/060H
Grundfos Circulator Sp3 (Default) Grundfos Circulator Sp2 Grundfos Circulator Sp1
NCB-H Flow Performance Curve
0
5
10
15
20
25
30
35
40
45
01234567891011
△P (psi)
Flow Rate (GPM)
NFC DHW Pressure Drop Curve
NCB-H DHW Pressure Drop Curve

10 About the Boiler
General Specifications
Item NCB-
190/060H
NCB-
190/080H
NCB-
240/110H
NCB-
240/130H NCB-250/150H
Dimensions 17.3 in (W) x 29.3 in (H) x 12.8 in (D)
Boiler Weight 87 lbs (40 kg) 96 lbs (44 kg)
Boiler Weight with Water 93 lbs (42 kg) 102 lbs (46 kg)
Installation Type Indoor Wall-Hung
Venting Type Forced Draft Direct Vent
Ignition Electronic Ignition
Natural Gas Supply
Pressure (from source) 3.5 in-10.5 in WC
Propane Gas Supply
Pressure (from source) 8.0 in-13.5 in WC
Natural Gas Manifold
Pressure -0.01 in WC to -0.31 in WC -0.06 in WC to -0.24 in WC -0.06 in WC to
-0.26 in WC
Propane Gas Manifold
Pressure -0.04 in WC to -0.33 in WC -0.06 in WC to -0.26 in WC -0.06 in WC to
-0.28 in WC
Flow
Rate
(DHW)
35°F (19°C)
Temp Rise
8.2 GPM
(31.1 L/m)
10.4 GPM
(39.5 L/m)
10.8 GPM
(40.9 L/m)
45°F (25°C)
Temp Rise
6.4 GPM
(24.2 L/m)
7.9 GPM
(30 L/m)
8.4 GPM
(31.8 L/m)
67°F (37°C)
Temp Rise
4.3 GPM
(16.2 L/m)
5.4 GPM
(20.3 L/m)
5.6 GPM
(21.2 L/m)
77°F (43°C)
Temp Rise
3.7 GPM
(14.0 L/m)
4.7 GPM
(17.8 L/m)
4.9 GPM
(18.5 L/m)
Gas Connection Size 3/4 in NPT
Power
Supply
Main Supply 120V AC, 60Hz
Maximum
Power
Consumption
Up to 15 amperes
Materials
Casing Cold-rolled carbon steel
Heat
Exchangers Stainless Steel
Venting
Exhaust
2 in or 3 in PVC, CPVC, approved polypropylene*
2 in or 3 in Special Gas Vent Type BH (Class III, A/B/C)
2 in or 3 in Stainless Steel
Intake
2 in or 3 in PVC, CPVC, polypropylene
2 in or 3 in Special Gas Vent Type BH (Class III, A/B/C)
2 in or 3 in Stainless Steel
Vent Clearance 0 in to combustibles
Safety Appliances
Flame Rod, APS, Ignition Operation Detector
Water Temperature High Limit Switch, Exhaust Temperature High Limit Sensor,
Water Pressure Sensor, Burner High Limit Fuse, Vent Installation Detector
Temperature Setting Range
Item Temperature Setting Range Remarks
Space
Heating
Supply 77–185°F (25-85°C) Actual supply and return temperatures vary
depending on the selected outdoor reset curve.
Return 68–158°F (20-70°C)
DHW 86°F-140°F (30°C-60°C)
Note For more information about the space heating temperature setting range, refer to“11.5.2 Setting the
Space Heating Operation” on page 107.

11About the Boiler
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
Ignitor & Flame
Rod
Exhaust
Vent Installation
Detector
Flue Duct
Air Vent
PCB
Power Switch
Air Filter
Mixing Chamber
Front Panel
Circulation Pump

12 About the Boiler
Premix Burner
Ignitor & Flame Rod
Vent Installation
Detector
Primary Heat
Exchanger
Secondary Heat
Exchanger
Pressure Sensor
(LWCO)
Water Adjust Valve
DHW Exchanger
Water Fill Valve
Heating Return
Domestic Cold
Pressure Relief Valve Adapter
Fan & Motor
Dual Venturi
High Limit Switch
Air Pipe
APS
Gas Valve
Gas Pipe
Mixing Valve
3-Way Valve
Heating Supply
Domestic Hot
Gas Inlet

13About the Boiler
1.5 Dimensions
The following diagrams show the dimensions of the boiler and the table lists the supply connections.
29.3" (745.2 mm)
Supply Connections
Description Diameter
APressure Relief Valve Adapter ¾ in
BAir Intake 2 in
CExhaust Gas Vent 2 in
DHeating Supply 1 in
EDomestic Hot ¾ in
FGas Connection ¾ in
GDomestic Cold ¾ in
HAuto Feeder Inlet (Make-up Water) ½ in
ICondensate Outlet ½ in
JHeating Return 1 in
Overhead View
3” (77 mm)
6.7” (170 mm)4.5”
(115 mm)
0.4“ (10 mm)
1.5”
(38 mm)14.3”(364 mm)
2.6”(67 mm)
AB C
Supply Connections
12.8” (325 mm)
3.5”
(88 mm)
2.9”
(74 mm)
2.5”
(63 mm)
2.7”
(68 mm)
17.3” (440 mm)
9.6” (244 mm)
2.4” (60 mm)
2.4” (60 mm)
2.7”
(69.5 mm)
3.3”
(85 mm)
D J
EH
FIG

14 About the Boiler
1.6 Rating Plate
The Navien NCB-H 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. If the boiler
does not match each of these ratings, do not install the boiler. If conversion to Propane Gas is required, the
included gas conversion kit must be used. Refer to “12.1 Gas & High Altitude Conversion” on page 123 for details.
WARNING
Ensure that the gas type and power source specifications match what is listed on the rating plate. Using a
different gas type will cause abnormal combustion and boiler malfunction. Using abnormally high or low AC
voltage may cause abnormal operation, and may reduce the life expectancy of the product.
This appliance complies with the requirements of SCAQMD Rule 1146.2 for NOx emissions of 14 ng/J or 20 ppm
at 3% O
2
.

15Installing the Boiler
2.1 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:
WARNING
Do not install outdoors. Outdoor installation
may result in property damage, severe personal
injury, or death. Damage to the boiler resulting
from installation outdoors is not covered by
warranty.
CAUTION
Review all of the installation information in this
manual before starting installation. Consider
all the requirements for venting, piping,
condensate removal, and wiring.
Compliance Requirements
●Local, state, provincial, and national codes, laws,
regulations, and ordinances.
●National Fuel Gas Code, ANSI Z223.1-latest
edition.
●Standard for Controls and Safety Appliances for
Automatically Fired Boilers, ANSI/ASME CSD-1,
when required.
●National Electrical Code.
●For Canada only: B149.1 Installation Code,
CSA C22.1 Canadian Electrical Code Part 1,
CSA-B214-12 Installation code for hydronic
heating systems, and any local codes.
Access to Utilities
●Water – the installation location should be near
where the domestic water supply enters the
building.
●Gas – the installation location should be near
where the gas supply enters the building.
●Electricity – the installation location should
be near where the electrical supply enters the
building.
Humidity and Contact with Water
When installing the boiler, avoid places with
excessive humidity. The boiler has electric gas
ignition components. Moisture can get inside
the boiler and damage the ignition system. The
boiler must be installed in a way to ensure that
the gas ignition system components are protected
from water (dripping, spraying, rain, etc.) during
operation and service.
Adequate Drainage
The boiler produces a significant amount of
condensate during operation. The boiler should be
located near a suitable drain and where damage
from a possible leak will be minimal. Installing the
boiler in a location without a drain will void the
warranty and Navien will not be responsible for
water damages that occur as a result. For more
information about condensate drainage, refer to“3.3
Connecting the Condensate Drain” on page 26.
The boiler must be located in an area where leakage
of the unit or connections will not result in damage
to the area adjacent to the appliance or to lower
floors of the structure. When such locations cannot
be found, installation of an adequately drained drain
pan under the boiler is highly recommended. When
installing the drain pan, ensure that the installation
does not restrict combustion air flow.
2. Installing the Boiler

16 Installing the Boiler
Adequate Installation Clearances
CAUTION
Do not install the boiler on carpeting.
Install the boiler in an area that allows for service
and maintenance access to utility connections,
piping, filters, and traps. Based on the installation
location, ensure that the following clearances are
maintained:
Top
Back
Side
Bottom
Front
Side
Clearance from: Indoor Installation
Top 9 in (229 mm) minimum
Back 0.5 in (13 mm) minimum
Front 4 in (100 mm) minimum
Sides 3 in (76 mm) minimum
Bottom 12 in (300 mm) minimum
CAUTION
It is necessary to leave clearance for service
access.
Adequate Venting and Ventilation
Select a location that requires minimal venting.
Consider venting restrictions caused by windows,
doors, air intakes, gas meters, foliage, and other
buildings. For more information about venting, refer
to “5. Venting for Combustion Air” on page 57.
To ensure adequate venting and ventilation, follow
these guidelines:
●Maintain proper clearances from any openings in
the building.
●Ensure that the vent termination is at least 12 in
(305 mm) above ground, 12 in (305 mm) above
the highest anticipated snow level, or as required
by local codes, whichever is greater.
●Maintain a minimum clearance of 4 ft (1.2 m) from
heating and cooling vents.
●Do not enclose the vent termination.
●Install the exhaust vent in an area that is free
from any obstructions, where the exhaust will not
accumulate.
●Do not install the boiler where moisture from the
exhaust may discolor or damage walls.
●Do not install the boiler in bathrooms, bedrooms,
or any other occupied rooms that are normally
kept closed or not adequately ventilated.
Proximity to Fixtures and Appliances
Install the boiler near fixtures that deliver or use
hot water, such as bathroom, kitchen, and laundry
room faucets. Select a location that minimizes the
water piping required between major fixtures. If the
distances are long or if the user requires “instant“
hot water, installation of a recirculation line which
circulates domestic hot water back to the boiler
from the furthest fixture is recommended. Insulate
as much of the hot water supply and recirculation
lines as possible. For more information about the
water supply, refer to“3.2 Installing a Domestic Hot
Water (DHW) System” on page 23.

17Installing the Boiler
2.2 Mounting the Boiler to the
Wall
Navien NCB-H boilers come with an upper
mounting bracket that is pre-drilled at 16 in
(400 mm) on center for easy installation on standard
wall studs. If the strength of the wall is insufficient
or if the framing is non-standard or uneven,
reinforce the area before installing the boiler. Avoid
installation on common walls as the unit will make
some operational noises while it is running.
To mount the boiler to the wall:
1. Affix the bracket securely to the wall and ensure
that it is level and that it can support the weight
of the boiler.
2. Align the grooves on the back of the boiler with
the tongues on the mounting bracket and hang
the boiler on the bracket.
When mounted with the mounting bracket, the
boiler will have a
5
/
8
in (16 mm) clearance from
the back of the wall.
3. Install two set screws through the bracket at the
bottom of the boiler to secure the boiler on the
wall.
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 similar chemicals
are used.
●Do not install the boiler in areas where gasoline or
other flammables are used or stored.
●Ensure that combustible materials are stored
away from the boiler and that hanging laundry or
similar items do not obstruct access to the boiler
or its venting.
Note The combustion air must be free of
flammable vapors or corrosive chemical
fumes. Common corrosive chemical
fumes to avoid include fluorocarbons
and other halogenated compounds
such as Freon, trichloroethylene,
perchloroethylene, chlorine, all of which
can be found in refrigerants or solvents.
When these chemicals burn, they
produce acids that corrode the stainless
steel heat exchanger, gaskets, and the
flue and vent system.
Operating Temperature
The ambient temperature at the installation location
must be above freezing temperature and below
100˚F (38˚C).
High Elevation Installations
●This unit may be installed at elevations up to
10,100 ft (3,078 m) for use with natural gas and
propane. Refer to “6. Setting the DIP Switches”on
page 72 for the appropriate altitude setting.
●Natural gas units require the use of a high
elevation kit if installed at an elevation of 5,400 ft
(1,646 m) or higher.
CAUTION
Follow the instructions in the guide provided
with the high altitude conversion kit when
replacing with the kit's gas orifice. Failure to
follow the instructions may result in property
damage, personal injury, or death.

18 Installing the Boiler
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.
●Do not rest the boiler on the bottom end
after removing it from the shipping carton.
Doing so may result in excessive pressure on
protruding pipes and resulting in product
damage. If you must put the boiler down, lay
it on its back or put it inside the protective
shipping base.
●Install the boiler in the upright, vertical
position. Installation in any other orientation
will result in improper boiler operation and
property damage, and could result in serious
personal injury or death.
CAUTION
●Ensure that the structure of the installation
location is sturdy enough to support the full
weight of the installed boiler, including the
water contained in the heat exchanger and
related piping.
●The wall must be vertical, and it must be
capable of carrying the weight of the boiler.
●Do not mount the boiler to drywall that has
not been reinforced.

19Installing the System Piping
Prior to connecting piping to the boiler, flush the
entire system to ensure it is free of sediment, flux,
solder, scale, debris or other impurities that may
be harmful to the system and boiler. During the
assembly of the heating system, it is important
to keep the inside of the piping free of any debris
including construction dust, copper burrs, sand and
dirt.
For retrofits, all system piping including radiators,
must be cleaned of all build-up including sludge
and scale. All systems, old and new, must be
cleaned to remove flux, grease and carbon residue.
Navien recommends cleaning the boiler system
with cleaning products specially formulated
for boiler systems. For retrofit applications with
heavy limescale and sludge deposits, a heavier
duty cleaner may be required. For information on
performing the cleaning, follow the instructions
included with the boiler system cleaner products.
WARNING
Failure to rid the heating system of the
contaminants listed above will void your
warranty and may result in premature heat
exchanger failure and property damage.
3.1 Installing a Space Heating
System
The water-tube type heat exchanger of the Navien
NCB-H boiler is designed to attain the highest level
of heat transfer in a compact design. To maintain
the efficient and reliable operation of the heat
exchanger, and to avoid heat exchanger failure, it
is critical to ensure the rules and guidelines in this
section are followed.
WARNING
●To avoid damaging the connectors on the
boiler, use two wrenches when tightening
piping to the boiler. Use one wrench to
prevent the connector at the boiler from
turning, and use the other wrench to tighten
the connection. Damaged connectors may
result in system leaks.
●Properly support the piping with hangers. Do
not allow the piping to be supported by the
boiler or its accessories.
CAUTION
Failure to follow the instructions provided in this
section will void the warranty and may result in
property damage, fire, serious injury or death.
3.1.1 Guidelines for a Space Heating
Installation
Read and follow the guidelines listed below to
ensure safe and proper installation of a boiler
heating system.
Freeze Protection for a Space Heating
System
●Freeze protection products may be used for the
space heating system. Freeze protection for new
or existing systems requires specially formulated
glycol, which contains inhibitors to prevent
the glycol from attacking the metallic system
components.
●Before using freeze protection products,
ensure that system fluid contains proper
glycol concentration and the inhibitor level
is appropriate. Navien recommends against
exceeding a 35% concentration of glycol.
●When using the freeze protection products, the
system must be tested at least once a year, and as
recommended by the manufacturer of the glycol
solution.
●When using the freeze protection products,
allowance should be made for expansion of the
glycol solution.
●Freeze damage is not covered by the warranty.
●The use of glycol results in a greater head loss due
to its higher viscosity compared to water.
WARNING
For systems requiring freeze protection, use only
inhibited propylene glycol, specially formulated
for hydronic heating systems; use of other types
of antifreeze may be harmful to the system and
will void the warranty.
3. Installing the System Piping

20 Installing the System Piping
3.1.2 Essential Elements in a Space
Heating System
Low Water Cut Off (LWCO) Appliance
Internal LWCO
The Navien NCB-H boiler is equipped with a factory-
installed, pressure-sensing type low water cutoff
(LWCO) device. The minimum operation pressure for
this device is 7.3 psig.
Note ●The boiler performs water
replenishment automatically when
the built-in water pressure sensor
detects insufficient water level in the
boiler system.
●If the water replenishment is not
completed after
5 minutes, error code E351 is displayed
on the front panel requiring a manual
boiler reset.
Refer to local codes to determine if a LWCO device is
required for your system and ensure that the built-in
device meets the requirements. Install a backflow
preventer in the make-up water line to the unit if
required by local codes.
External LWCO
Install a separate LWCO device if required by local
codes. The following figure illustrates an example of
typical LWCO installation.
External LWCO
6" (152 mm) min.
Figure 1. External LWCO
(without Navien Manifold System)
System Pressure
●The Navien NCB-H boiler is intended solely for
use in pressurized closed loop heating systems
operating with 12-30 psi water pressure at the
boiler outlet. To obtain the minimum system
design pressure, follow the piping diagrams
illustrated in this section.
●The Navien NCB-H boiler’s space heating system
is not approved for operation in an “open system”,
thus it cannot be used for direct potable water
heating or to process heating of any kind.
Oxygen Elimination
This boiler may only be installed in a pressurized
closed-loop heating system, free of air (oxygen) and
other impurities. To avoid the presence of oxygen,
ensure all of the air is removed from the system
during commissioning via strategically placed and
adequately sized air removal appliances, located
throughout the heating system.
Note See the examples of system application
at the end of this section detailing the
installation location of the air removal
appliances, in case an additional air
removal appliances is required for a
specific application.
WARNING
●Immediately repair any leaks in the system
piping to avoid adding make-up water.
Make-up water adds oxygen and minerals to
the system that may lead to heat exchanger
failure.
●Failure to follow these instructions may result
in poor performance, unnecessary wear of
system components and premature failure.
CAUTION
Do not solder piping directly onto the water
connections, as the heat may cause damage
to internal components. Use threaded water
connections only.