Intellihot iN401 User manual

Operation & Installation Manual
iN401
iN501
WARNING
If the information in these instructions is not followed
exactly, a re or explosion could result causing
property damage, personal injury, or death.
— Do not store or use gasoline or other ammable
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
re department.
— Installation and service must be performed by
a qualied installer, service agency, or the gas
supplier.
— Ne pas entreposer ni utiliser d’essence ou
ni d’autres vapeurs ou liquides inammables
à proximité de cet appareil ou de tout autre
appareil.
QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE GAZ
• Ne pas tenter d’allumer d’appareil.
• Ne touchez à aucun interrupteur; ne pas vous
servir des téléphones se trouvant dans
le bâtiment.
• Appelez immédiatement votre fournisseur de gaz
depuis un voisin. Suivez les instructions
du fournisseur.
• Si vous ne pouvez rejoindre le fournisseur,
appelez le service des incendies.
— L’installation et l’entretien doivent être assurés
par un installateur ou un service d’entretien
qualié ou par le fournisseur de gaz.
AVERTISSEMENT
Assurez-vous de bien suivre les instructions données
dans cette notice pour réduire au minimum le
risque d’incendie ou d’explosion ou pour éviter tout
dommage matériel, toute blessure ou la mort.

Thank you for purchasing this Intellihot unit.
This unit is designed for years of trouble free operation, and I urge you to read and follow the
instructions in this “Operation & Installation Manual.”
Our mission to create a better heating system began back in the winter of 2005 when a tank
water heater broke down and ooded my basement. By combining the principles of a diesel
engine’s robustness, robotics intelligence, and marine environment durability, we set out to
design a unit from the ground up that would outperform and outlast all others.
Quickly, our goal grew from not just making a better water heater, but creating an intelligent
water heating and delivery system. Innovation is our hallmark and simplicity, eciency, and
durability are at the core of every lntellihot product.
Our products are proudly engineered and built in Galesburg, Illinois. lntellihot has helped
commercial customers throughout the nation save thousands of dollars while eliminating
downtime. Our talented team of dedicated professionals is ready to assist you and help your
business succeed.
I thank you for purchasing our lntellihot products.
Sincerely,
Sri Deivasigamani
CEO, lntellihot Inc.

Table of Contents
1. General Information
1.1 Items Shipped With Water Heater..........2
1.2 Serial Number Locations .................2
2. Safety
2.1 Safety Signal Words.....................3
2.2 Installation Warnings ....................3
3. TechnicalSpecications
3.1 ....................5
3.2 Nomenclature..........................6
3.3 High Elevation Installations ...............6
3.4 ClearanceRequirements .................6
3.5 7
3.6 Exhaust Gas Standards ..................7
3.7 Overall Dimensions......................8
3.8 ...................9
4. Quick Reference Installation Guide
4.1 Install the Water Heater..................11
4.2 Pre-Startup Instructions .................11
5. Preparation Before Installation
5.1 Selecting an Indoor Installation Site ....... 13
6. Gas Connection
6.1 QuickReferenceInstallationInstructions ... 14
6.2 Fuel Source .......................... 14
6.3 GasPressureRequirements ............. 14
6.4 GasPressureRegulator ................. 14
6.4.1 VentingofGasSupplyRegulators... 15
6.5 Length of Gas Supply Line............... 15
6.6 Gas Piping Material .................... 15
6.7 DetermineCorrectGasPipeDiameter ..... 15
6.8 15
6.9 ConnectingGasLinetoUnit ............. 16
6.10 Gas Pipe Sizing Tables ...................17
7. Air Intake Inlet and Exhaust Gas Outlet Pipe
Connections
7.1 QuickReferenceInstallationGuide ........ 19
7.2 TypicalSingleUnitAirIntakeInletand
Exhaust Gas Outlet Pipe Installation ....... 19
7.3 Two Pipe Vent System (Direct Vent) ......20
7.3.1 ....20
7.3.2 ...... 21
7.3.3 SideWallAirIntakeInletandExhaust
Gas Outlet Pipe Termination ....... 21
7.3.4 RoofAirIntakeInletandExhaust
Gas Outlet Pipe Termination .......22
7.4 Single Pipe Venting System (Power Vent) ..22
7.4.1 SingleUnit .....................22
7.4.2 MultipleUnits...................23
7.5 CombustionAirRequirements ............24
7.6 IntakeAirInletandExhaustGasOutlet
Pipe Diameter and Length ...............24
7.7 ........25
7.8 Exhaust Gas Outlet Pipe Materials ........26
7.9 AirIntakeInletPipeVentMaterials ........26
7.10 RecommendedExhaustGasOutletPipe
Transitions ........................... 27
8. Water Connections
8.1 QuickReferenceInstallationInstructions ...28
8.2 HotWaterConnection ..................28
8.3 ColdWaterConnection .................29
8.4 29CondensateDrainLine ......... .........
9. Electrical Power
9.1 ElectricalRecommendations ............. 31
9.2 ConnectionInstructions................. 31
10. Adjusting CO2Level
10.1 General Information ....................32
10.2 AdjustmentProcedure ..................32
11. Natural Gas to Propane Conversion
11.1 General Information ....................35
11.2 ConversionProcedure .................35
12. Operation
12.1 ControlPanel ......................... 37
12.2 Turning Water Heater ON and OFF ........ 37
12.3 Setting the Time ......................38
12.4 AdjustingtheWaterTemperature .........38
12.5 Security .............................39
12.5.1 Setting Passcode Protection.......39
12.5.2 ChangingPasscode ..............40
12.5.3 Forgot Passcode ................ 41
12.6 N/A ............................. 41
12.7 Temp / Flow......................... 41
12.8 Life Screen .......................... 42
12.9 Unit Information ...................... 43
12.10 More Screens. ........................ 44
12.10.1 Cellular ........................44
12.10.2 Error History ...................44
12.10.3telliCareService
(Subscribe at Startup)............45
13. Connecting Multiple Units
13.1 General Information ....................48
13.2 Installation Procedure ..................48
13.2.1 telliCareforMultipleUnits.........49
13.3 VentingforMultipleUnits ...............49
14. Maintenance
14.1 Maintenance-FreeCirculationPump.......50
14.2 Heat Engine Locations ..................50
14.3 CondensateSedimentCupCleaning .......50
15. Wiring Diagrams and Troubleshooting
15.1 OperationalFlowChart .................53
15.2 CompleteWiringDiagram(allmodels) .....54
15.3 ControlBoardWiringDiagram ............55
15.4 Troubleshooting Guide..................56
17.Requirements for State of Massachusetts
17.1 Notice Before Installation .............68
..............69
18. Warranty
18.1 Warranty. ..............
19. Product Warranty
19.1 Warranty. ............................71
Specifications Chart. .
Connection Specifications. ...............
Configuration Options
Single Unit Configurations. . . . .
Multiple Unit Configurations .
Venting Clearance Specifications. .
16. Serviceable parts. . . . . . . . . . . . . . . . . . . . . . . 57
Gas Pipe Drip Leg and Shut-off Valve .....

1 iN401 - iN501
May2019-Revision00
WARNING
If the information in these instructions is not followed
exactly, a re or explosion could result causing
property damage, personal injury, or death.
— Do not store or use gasoline or other ammable
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
re department.
— Installation and service must be performed by
a qualied installer, service agency, or the gas
supplier.
This product complies with ANSIZ21.10.3 (2011) / CSA 4.3 Gas Water Heater. For use as potable water heating.
Certified to
NSF/ANSI 372
DANGER
To avoid product damage, personal injury, or
even possible death, carefully read, understand,
and follow all the instructions in this Operation
and Installation manual before installing this
product. Improper installation, adjustment, alteration,
or maintenance can cause injury, loss of life, and/or
property damage. This water heater should be installed
and serviced by a qualified technician. The lack of
proper service can result in a dangerous condition.
Due to Intellihot’s policy of continuous product improvement
and technology, the design and/or technical specifications in
this manual are subject to change without notice.
This manual contains safety information, installation
instructions, and maintenance procedures. It must be left
with the homeowner or placed near the water heater in a
noncombustible location. The customer should retain this
manual for future reference.
— Ne pas entreposer ni utiliser d’essence ou
ni d’autres vapeurs ou liquides inammables
à proximité de cet appareil ou de tout autre
appareil.
QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE GAZ
•Ne pas tenter d’allumer d’appareil.
•Ne touchez à aucun interrupteur; ne pas vous
servir des téléphones se trouvant dans
le bâtiment.
•Appelez immédiatement votre fournisseur de gaz
depuis un voisin. Suivez les instructions
du fournisseur.
•Si vous ne pouvez rejoindre le fournisseur,
appelez le service des incendies.
— L’installation et l’entretien doivent être assurés
par un installateur ou un service d’entretien
qualié ou par le fournisseur de gaz.
AVERTISSEMENT
Assurez-vous de bien suivre les instructions données
dans cette notice pour réduire au minimum le
risque d’incendie ou d’explosion ou pour éviter tout
dommage matériel, toute blessure ou la mort.
Contact Information
Call us, your dealer, first if you have any questions about this
product. We can help answer questions about installation,
operation, or if there are damaged or missing parts when
unpacking this unit from the shipping box.
Dealer Contact Information

iN401 - iN501 General Information 2
May2019-Revision00
1. General Information
1.1 Items Shipped With Water Heater
The shown in the illustration are shipped loose with the water
heater.
Temperature and
Pressure Relief Valve
(must be installed)
Operator
Manual
Communication
Cable
Keys
1.2 Serial Number Locations
The unit’s serial number is located on the left side of the
unit.Please provide this serial number when inquiring about
service or warranty solutions. ASME detail is located on the
information plate attached to the cabinet next to the rating
label on the left side.
UnitSerialNumber:______________________________
HeatEngine1(ASME)SerialNumber:_____________
HeatEngine2(ASME)SerialNumber:_____________
DateofInstallation:___ / ___ / ______

3 iN401 - iN501 Safety
May2019-Revision00
2. Safety
2.1 Safety Signal Words
DANGER
Indicates an imminently hazardous situation which, if
not avoided, will result in death or serious injury. This
signal word is limited to the most extreme situations.
WARNING
Indicates a potentially hazardous situation which, if not
avoided, could result in death or serious injury.
CAUTION
Indicates a potentially hazardous situation which, if not
avoided, may result in minor or moderate injury.
NOTICE
Indicates that equipment or property damage can result if
instructions are not followed.
SAFETY
INSTRUCTIONS
Safety instructions (or equivalent) signs indicate
specific safety-related instructions or procedures.
Note: Contains additional information important to a
procedure.
2.2 Installation Warnings
WARNING
DO NOT use this water heater for any purpose other
than water heating.
Read, understand, and follow the Installation and Operation
manuals, including all warnings and precautions, before
operating this water heater. If you do not follow these
instructions exactly, a fire or explosion may result, causing
property damage, personal injury, or loss of life.
Follow all local codes and the most recent edition of the
National Fuel Gas Code (ANSI Z223.1/NFPA 54) in the USA
or the Natural Gas and Propane Installation Code in Canada
(CSA B149.1).
This water heater must be installed by a licensed plumber,
gas fitter, and/or professional service technician. Installation
by unqualified person(s) voids the warranty.
Designed for operations at outlet temperature(s) not in
excess of 190°F (88°C).
DANGER
A. This water heater does not have a pilot. It is equipped
with an ignition device which automatically lights the
burner. Do not try to light the burner manually.
B. BEFORE OPERATING, smell all around the water
heater area for gas. Be sure to smell next to the floor
because some gas is heavier than air and will settle
on the floor.
WHAT TO DO IF YOU SMELL GAS:
• Do not try to light any appliance.
• Donot touch any electric 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 or
police department.
C. Use only your hand to turn the manual gas shut-off
valve. Never use tools. If manual gas shut-off valve will
not turn by hand, don’t try to repair it. Call a qualified
service technician. Force or attempted repair may
result in a fire or explosion.
WARNING
DO NOT use or store flammable liquids around the water
heater, including gasoline, oils, spray paints, etc.
DO NOT operate this water heater unless it is properly
vented to the outside (the exhaust vent piping must be
connected from the unit directly to the outside). Improper
venting can cause a build-up of carbon monoxide, which
can result in brain damage or death. Exhaust gases must
be completely expelled out of the building.
This water heater is factory preset for NATURAL GAS
but may be field converted for use with propane.
For propane conversion, refer to the Propane (LPG)
Conversion section of this manual. Connecting the
water heater to any other gas supply can result in
property damage, serious injury, or even death.
This water heater is suitable for use in potable water
heating applications. The cold and hot water fittings on
the top of the water heater MUST NOT be connected to
any heating system.
The water heater temperature is factory set to 120°F
(49°C). Hot water temperatures above 125°F can cause
severe burns instantly or death from scalds. If the
proposed water heater outlet temperature is to be set
above 125°F, installation of a thermostatically controlled
(or temperature limiting) mixing valve is recommended
for all hot water going to faucets to avoid the risk
of scalding. Examples include commercial applications
where 140°F (60°C) is often needed or if the space
heating temperature required is higher than the domestic
hot water. Always check the temperature of the hot
water before bathing, showering, washing, etc.
Protect against snow and debris accumulation around
the vent terminations. Regularly inspect the exhaust
vent pipe and the air intake pipe to ensure they remain
clear from obstructions at all times.

iN401 - iN501 Safety 4
May2019-Revision00
CAUTION
Make sure you know the location of the gas shut-off
valve and how to operate it. Immediately close the
gas shut-off valve if the water heater is subjected to
fire, overheating, flood, physical damage, or any other
damaging condition that might affect the operation of
the unit. Have the water heater checked by a qualified
technician before resuming operation.
If the water quality is known to have high acidity and/
or high hardness, water treatment is recommended.
Consult the local water authority.
SAFETY
INSTRUCTIONS
DO NOT use this appliance if any part has been under
water.
DO NOT reverse the cold water and gas connections as
this will damage the gas valve.
DO NOT overtighten fittings as damage may occur,
causing internal leakage.
The appliance should be located in an area where leakage
within the unit or at its connections will not result in
damage to the surrounding area. The manufacturer
will not be responsible for any damage resulting from
leaking if adequate drainage is not provided.

5 iN401 - iN501 Technical Specifications
May2019-Revision00
3. Technical Specifications
3.1 Specifications Chart
Technical Data
Specification
iN401 iN501
Type Indoor, Floor-Mounted
Fuel Preset for natural gas but convertible to propane
Minimum Input (BTUs/hour) 30,000
Maximum Input (BTUs/hour) 399,999 499,999
Maximum Output (BTUs/hour) 375,999 469,999
Thermal Efficiency 94%
Turn Down Ratio (TDR) 13.3:1 16.7:1
Water Inlet / Outlet Connection 1-1/2” NPT
Gas Inlet Connection 1-1/2” NPT
Condensate Drain Connection 3/4” PVC
Maximum Condensate Flow Rate (GPM) 2.8 3.6
Dimensions H X W X D (inches) 67.5 X 20 X 20 (15.6 cu. ft)
Service Clearances 1” on all sides, 6” on top, 12” in front (Required for proper service)
Weight (lbs) 345
Venting Type Direct Vent (2 pipe – air intake and exhaust gas outlet), Power Vent (1 pipe – exhaust gas only)
Venting Materials (USA) Sch. 40 PVC, Sch. 40 CPVC, Polypropylene, Stainless Steel (AL29-4C)
Venting Materials (Canada) Type BH Gas Vent Classes: II A (PVC), II B (CPVC), II C (Polypropylene), I (AL294C SS)
Venting Size (Diameter) 4”
Max 4” Vent Length – Single Pipe/Power Vent 250’ * 180’ *
Max 4” Vent Length – Two Pipe / Direct Vent 125’ * 90’ *
* Venting Note: From the maximum length above, deduct 5 ft. per 90° elbow and 2 ft. per 45° elbow.
Ignition Electronic Spark Ignition
Temperature Range 100°F – 190°F
Temperature Stability +/- 4°F
Installation Location Ambient Temperature 40°F – 130°F
Safety Flame Rod, Thermal Fuse, Overheat Prevention Device, Fan Speed Monitor, Flue Temperature Monitor, Blocked Vent Detector, Dual Flame
Sensing
Water Pressure Min / Max (PSI) 30/160
NG/LP- Min. Gas Pressure (Full Fire) 2.5” W.C.
NG/LP - Maximum Static Gas Pressure 14” W.C.
Gas Pressure for Adjustments 8” W.C. for Natural Gas, 11” W.C. for Propane
Electrical 120V AC, 60 Hz
Power Consumption Max 9.5 Amps, 16W (Standby)
Internal Water Volume (gallons) 1
Features and Approvals iN401 iN501
Built-In Redundancy Multiple Heat Exchangers with Individual Control
Cascading Masterless,, Automatic Rotation
Common Venting Yes, Up to 4 Units
Heat Exchanger Expandable, Stainless 316L
Appliance Certication to ANSI Z21.10.3 ETL
SCAQMD Ultra Low Nox (under 20 PPM)
ASME HLW
Performance Specification
Hot Water Output (45°F Rise) 16.8 21.0
Hot Water Output (70°F Rise) 10.8 13.5
Hot Water Output (90°F Rise) 8.4 10.5
Hot Water Output (100°F Rise) 7.6 9.4
Hot Water Output (140°F Rise) 5.4 6.7
Warranty Heat Engine Coil – 10 years, All Other Parts – 2 years
Note: Due to continuous product improvements, the design and technical specifications are subject to change without notice.

iN401 - iN501 Technical Specifications 6
May2019-Revision00
3.2 Nomenclature
Gas Inlet
Air Intake
Exhaust Port
Pressure
Relief Valve
Hot Water Outlet
Recirculation Inlet
Cold Water Inlet
Drain
Hose
3.3 High Elevation Installations
For operation at elevations above 2,000 feet, the hot water
delivery capacity should be reduced by 4% for each 1,000
feet above sea level.
Clearance Requirements
In order for the water heater to operate properly and
efficiently, the clearances specified in the table below are
required.
12”
1”
1”
1”
6”
(top)
Service Clearances. If multiple units are installed, the side clearance can be
shared between the two units.
Location Required
From
Combustibles
From Non-
Combustibles
Service
Clearance1
Top 6” (15 cm) 2” (51 cm) 6” (15 cm)
Back 5/8” (16 mm) 5/8” (16 mm) 1” (25 mm)
Sides 1” (25 mm) 1/2” (13 mm) 1” (25 mm)
Front 2” (5 cm) 2” (5 cm) 12” (31 cm)
Bottom 0” (0 mm) 0” (0 mm) 0” (0 mm)
1Service clearances are required dimensions to allow for normal
service of the unit.

7 iN401 - iN501 Technical Specifications
May2019-Revision00
3.4 Connection Specifications
Connections
Description Specification2
GasSupplyInletConnection 1-1/2” NPT
WaterSupplyInletConnection 1-1/2” NPT
HeatedWaterOutletConnection 1-1/2” NPT
Exhaust Gas Vent14” Polypropylene
AirIntakeInlet14” Polypropylene
CondensateDrainConnection 3/4”
Power Supply 120VACPower, Max. 9.5A
1Use the 4” adapter provided when using PVC or CPVC pipe.
2Using sizes other than specified can cause damage to the water heater
and will void the warranty.
3.5 Exhaust Gas Standards
CO2and CO Standards
Description CO2Range (%) Max. CO Level (ppm)
Natural Gas
High Fire 9.1% to 9.3% < 200 ppm
Low Fire 9.1% to 9.3% < 60 ppm
Propane Gas
High Fire 10.1% to 10.5% < 200 ppm
Low Fire 10.1% to 10.5% < 60 ppm

iN401 - iN501 Technical Specifications 8
May2019-Revision00
3.6 Overall Dimensions
508,00
[20.00]
160,34
[6.31]
465,14
[18.31]
1713,50
[67.46]
254,00
[10.00]
54,36
[2.14] 262,50 [10.33]
102,45
[4.03]
303,11
[11.93]
151,55
[5.97]
3X ?15,88
[0.63]
25,00
[0.98]
3,99
[0.16]
29,77
[1.17]
134,25
[5.29]
50,80
[2.00]
50,80
[2.00]
3X 90,00
[3.54]
90,00
[3.54]
279,00
[10.98]
429,00
[16.89]
405,50
[15.96]
3X 24,00
[0.94]
254,00
[10.00]
356,81
[14.05] 60,00 [2.36]
158,00
[6.22]
254,00
[10.00]
FRONT DISPLAY
1-1/2" NPT WATER INLET
RECIRCULATION RETURN
ELECTRICAL ACCESS PANEL
1-1/2 NPT GAS INLET
1-1/2 NPT WATER OUTLET
4" PVC OR PP EXHAUST
4" PVC OR PP AIR INTAKE
3/4" NPT T&P PORT
POWER
(CABLE STRAIN RELEIF)
3/4" PVC CONDENSATE DRAIN
REAR SIDE FRONT
BOTTOM
TOP

9 iN401 - iN501 Technical Specifications
May2019-Revision00
3.7 Configuration Options
Hot Water
Supply
Gas Supply
Cold Water Supply
Expansion Tank
HOT WATER FIXTURES
Recirculation Line
Hot Water Return
Isolation Valve
Check Valve
Pipe Coupling
Pipe Cap
Recirculation Pump
LEGEND
Pressure Relief Valve
System with no storage tank and without mixing valve.
Supply
Gas Supply
Cold Water Supply
Expansion Tank
HOT WATER FIXTURES
Recirculation Line
Hot Water Return
Traditional
Tank-Type Heater
Isolation Valve
Check Valve
Pipe Coupling
Pipe Cap
Recirculation Pump
LEGEND
Pressure Relief Valve
Multiple unit system with mixing valve but no storage tank.

iN401 - iN501 Technical Specifications 10
May2019-Revision00
Hot Water
Supply
Gas Supply
Cold Water Supply
ExpansionTank
HOT WATER FIXTURES
Recirculation Line
Hot Water Return
Isolation Valve
Check Valve
Pipe Coupling
Pipe Cap
Recirculation Pump
LEGEND
Pressure Relief Valve
Multiple unit system with mixing valve but no storage tank.

11 iN401 - iN501 QuickReferenceInstallationGuide
May2019-Revision00
4. Quick Reference Installation Guide
4.1 Install the Water Heater
When installing the water heater, follow all local building
codes and the current edition of the National Fuel Gas Code
(ANSI Z223.1/NFPA 54) in the USA, or National Gas and
Propane Installation Code (CAN/CGA B149.1) in Canada.
Note: For water heater installations in Massachusetts,
refer to section, “16. Requirements for State of
Massachusetts” on page 60.
1. Select an installation location
For an interior or exterior location refer to section “5.
Preparation Before Installation” on page 13.
2. Check the quality of the water to determine if additional
treatment would be beneficial to the function and
efficiency of the water heater. For additional information
refer to section “5. Preparation Before Installation” on
page 13.
3. Make all necessary gas connections.
For additional information refer to section “6. Gas
Connection” on page 14.
4. Make all necessary venting connections.
For additional information refer to section “7. Air Intake
Inlet and Exhaust Gas Outlet Pipe Connections” on page
19.
5. Make all necessary water connections.
For additional information refer to section “8. Water
Connections” on page 28.
6. Make all necessary electrical connections.
“9. Electrical Power” on page 31.
Note: For additional electrical protection, the use of
a surge protection device is recommended. Damage
caused by power surges is not covered by the warranty.
7. If necessary, convert the water heater from the factory
preset of using natural gas to using propane. Refer to “11.
Natural Gas to Propane Conversion” on page 35 for
the required instructions.
8. As part of the propane conversion process, the CO2
and CO values must be adjusted. This process is also
required when installing the water heater at altitudes over
8,000 feet. This procedure should be performed only by
a qualified technician. To check and/or adjust the CO2
and CO levels, refer to “10. Adjusting CO2 Level” on page
32.
9. If connecting multiple units together, refer to “13.
Connecting Multiple Units” on page 48.
10. Fill out the Warranty Card and return it to Intellihot. For
a copy of the card go to “18. Product Warranty” on page
63.
4.2 Pre-Startup Instructions
1. Recheck the hot and cold water lines, the gas line,
condensate drain line, the fresh air inlet, and exhaust vent
to make sure they are properly connected.
Gas Inlet
Air Intake
Exhaust Port
Pressure
Relief Valve
Hot Water Outlet
Recirculation Inlet
Cold Water Inlet

iN401 - iN501 QuickReferenceInstallationGuide 12
May2019-Revision00
2. Open the gas supply valve, cold water valve, and hot water
valve.
Hot
Water
Valve
Gas
Valve
Cold
Water
Valve
3. With the unit OFF, open a nearby hot water faucet and
allow the water to run through the unit until all the air is
removed from the water lines and from the water heater.
4. If multiple units are being installed, follow these
instructions for each unit.
5. Turn ON the power switch at the electrical junction box
and turn ON the ON/OFF switch inside the front cabinet
door. The water heater’s display panel should turn ON.
6. Follow the instructions in this manual and on the unit’s
display screen. For additional information refer to section
“12. Operation” on page 37.

13 iN401 - iN501 Preparation Before Installation
May2019-Revision00
5. Preparation Before Installation
5.1 Selecting an Indoor Installation Site
Note: When installing the water heater, follow all local
building codes and the current edition of the National
Fuel Gas Code (ANSI Z223.1/NFPA 54) in the USA,
or National Gas and Propane Installation Code (CAN/
CGA B149.1) in Canada when installing this product.
Note: For water heater installations in Massachusetts,
refer to section “16. Requirements for State of
Massachusetts” on page 60.
1. Select an interior location for the installation. Each
installation is unique; therefore, take the time to find the
best location for the water heater.
a. Install the water heater near locations that use hot
water, such as bathroom, kitchen, or laundry room
faucets.
b. Select a location that minimizes the length of the
water pipe.
c. If the distances are long or if the faucet or appliance
requires “instant” hot water, we recommend running
a recirculation line back to the water heater from the
farthest fixture.
d. Insulate the hot water supply and recirculation lines.
e. Select a location away from foot traffic and away from
areas where dust, debris, chemical agents, or other
combustible materials could accumulate.
f. Allow sufficient space for service and maintenance
access to all gas, water, and drain connections.
g. Make sure the location meets all building code
requirements.
2. Minimize the distance that the exhaust gas outlet and air
intake inlet must travel to an exterior wall.
a. The exhaust vent outlet must not be located next to
a walkway, near soffit vents, crawl space vents, or
other areas where condensate (water vapor) could
cause damage or create a hazard. Refer to the
Venting Clearance Specications section for additional
information.
b. The fresh air inlet vent must be separated from the
exhaust vent per guidelines in section “7. Air Intake
Inlet and Exhaust Gas Outlet Pipe Connections” on
page 19.
c. Contaminated or dirty air drawn into the intake pipe
can damage the water heater. The warranty does not
cover damage caused by airborne contaminants.
3. Locate the unit close to a drain and near gas and water
connections.
The water heater produces a significant amount of
condensate during normal operation and should be
located near a suitable drain where damage from a
possible leak will be minimal. Installing the water heater
in a location without a drain will void the warranty
and the manufacturer will not be responsible for any
resulting water damages that may occur. For additional
information, refer to the Condensate Line Installation
section.
4. Locate the water heater and all the water pipes in an area
where the ambient temperature always remains above
freezing.
a. When the water heater is connected to an electrical
power supply, it will automatically prevent the water
from freezing inside the unit.
b. The unit’s freeze protection system will not prevent
the water in the external piping from freezing.
NOTICE
In cold climates, if there is a power failure, the unit’s freeze
protection system will not operate and can result in water
freezing inside the heat engine. To prevent damage to
the water heater, turn OFF the gas supply and inlet water
valve. Drain the unit completely. Damage caused by
freezing water is not covered by the warranty.
5. Select an appropriate location for the combustion air and
exhaust pipes to exit the building, as shown in the Venting
Clearance Specications section in this manual.
6. Check the water quality.
Proper maintenance of the water heater is required to
ensure that the water meets EPA quality standards. The
following table shows the maximum contaminant levels
allowed, based on the EPA National Secondary Drinking
Water Regulations (40 CFR Part 143.3). Refer to section
“17. Warranty” on page 61 for additional information.
If you suspect that your water is contaminated in any
way, discontinue use of the water heater and contact an
authorized technician or licensed professional.
If the incoming water is known to have a high mineral
content or “hardness” (see warranty section), treatment
is recommended upstream from the water heater.

iN401 - iN501 GasConnection 14
May2019-Revision00
6. Gas Connection
WARNING
FIRE AND/OR EXPLOSION HAZARD
To avoid serious injury or even death, the gas line
installation and the gas line inlet pressure test must be
done by a licensed professional.
Always match the water heater with the type of gas
supplied to the unit (natural gas or propane). The water
heater is factory preset for natural gas.
Make sure the gas line pressures are within normal
limits. Pressures outside normal limits can result in
poor performance and hazardous operating conditions.
6.1 Quick Reference Installation Instructions
1. Determine fuel source; natural gas or propane as shown in
“6.2 Fuel Source” on page 14.
2. Measure gas pressure as shown in “6.3 Gas Pressure
Requirements” on page 14.
3. Install a gas pressure regulator and vent line if gas
pressure is above maximum recommendations as shown
in “6.4 Gas Pressure Regulator” on page 14.
4. Measure the length of the supply line as shown in “6.5
Length of Gas Supply Line” on page 15”.
5. Select the proper gas piping material as shown in “6.6
Gas Piping Material” on page 15.
6. Select the proper gas piping diameter as shown in “6.7
Determine Correct Gas Pipe Diameter” on page 15.
7. Install a drip leg on the gas piping as shown in “6.8 Gas
Pipe Drip Leg and Shut-off Valve” on page 15.
8. Install a manual shut-off valve as shown in “6.8 Gas Pipe
Drip Leg and Shut-off Valve” on page 15.
9. Test all gas line connections for leaks.
NOTICE
Do not fire (operate) the water heater until all connections
have been completed and the heat engine is filled with
water.
6.2 Fuel Source
1. Natural gas is the factory preset.
2. To convert the unit to propane, refer to the Propane
(LPG) Conversion section in this manual.
6.3 Gas Pressure Requirements
iN series water heaters are designed to operate at gas
pressures as low as 2.5” WC (at maximum firing rate). Gas
inlet pressures to each unit should not exceed 14” WC under
any condition (when unit is firing or not firing).
Natural Gas Static Gas Pressure
Parameters Specifications
Minimum Static Gas Pressure 2.5”W.C.(non-corrugated,black
iron)
RecommendedGasPressure 8”W.C.
Maximum Static Gas Pressure 14”W.C.
6.4 Gas Pressure Regulator
1. If the gas inlet pressure is higher than recommended,
install a gas pressure regulator to lower gas pressure to
an acceptable level.
2. The gas pressure regulator must have the same or higher
minimum to maximum modulation range as the model it is
regulating. For example, an iN401 gas pressure regulator
should have a modulation range of 30,000 BTU/h to
399,999 BTU/h.
3. Regulators should be mounted with a minimum of 12” of
straight length pipe on either side and a recommended 6
ft from the appliance. If regulator manufacturer
recommends more distance, then follow their guidelines.

15 iN401 - iN501 GasConnection
May2019-Revision00
4. When multiple units are connected use a dedicated gas
pressure regulator for each unit.
5. To convert the unit to propane, refer to the Propane
(LPG) Conversion section in this manual. For additional
information refer to “11. Natural Gas to Propane
Conversion” on page 35.
6.4.1 Venting of Gas Supply Regulators
Make sure the gas supply regulator is properly vented by
following all local codes and the gas regulator manufacturer’s
recommendations.
1. The vent pipe must be at least the same size as the
regulator vent.
2. When multiple units are connected, each regulator must
have a separate vent line.
3. Vent lines must not be connected together or connected
with any other appliance requiring external venting.
4. When selecting the size, the pipe diameter must be
increased by one size for every 20 feet of pipe.
a. Each 90° elbow is equivalent to approximately:
4.5 feet for nominal pipe sizes of up to 1-1/2”
10.5 feet for nominal pipe sizes of up to 4”.
b. Each 45° elbow is equivalent to approximately:
2 feet for nominal pipe sizes of up to 1-1/2”
5 feet for nominal pipe sizes of up to 4”.
6.5 Length of Gas Supply Line
1. Make sure the length supply line is correctly sized.
a. Measure the length of the gas supply line from the
gas meter to the water heater or other appliances
requiring gas. The diameter of the pipe must be in
relation to the length.
b. The total length of gas piping, as well as fitting pressure
drop, must be considered when sizing the gas piping.
Total equivalent length should be calculated from the
meter or source location to the last heater connected.
c. Gas pipe size should be selected on the total
equivalent length. The gas volume for cfh flow will be
the input divided by the calorific value of the fuel to be
supplied.
d. Use the Gas Pipe Sizing tables in this manual or refer
to the gas line manufacturers sizing information to
determine the correct diameter for the supply pipe.
e. The diameter of the gas lines, shown in the illustration,
will vary according to the specific installation
requirements.
6.6 Gas Piping Material
1. All gas piping and components must comply with NFPA
local codes, and utility requirements minimum. Only gas
approved fittings, valves, or pipe should be utilized.
2. Standard industry practice for gas piping is Schedule 40
iron pipe and fittings. All high and low gas pressure piping
systems must comply with local utility and building codes.
3. Assembled piping should be clean of all scale, debris,
metal particles, or foreign material.
4. The piping must be supported from the floor, ceiling, or
walls and by the water heater itself.
6.7 Determine Correct Gas Pipe Diameter
Note: The water heater should be the first appliance to be
connected to the gas supply line.
1. Determine the gas requirement of the water heater(s)
and other appliances requiring gas.
2. Size the pipe diameter according to the COMBINED total
maximum BTUH volume for all the appliances as if they
were all operating at the same time. Use the “6.10 Gas
Pipe Sizing Tables” on page 17.
3. Select the proper header pipe according to the number of
units being connected together, as shown in the chart.
Header Sizing for Multiple iN Units
Number of
Heaters 1 2 3 4
Sch 40 Iron
Pipe 2” 2” 3” 3”
4. The maximum pressure drop from the source to the final
water heater must not exceed 0.3” W.C.
5. The maximum gas flow rate required is the sum of
the maximum inputs of each unit divided by the heat
of combustion of the fuel supplied at the location,
(approximately 1,030 BTU per cubic foot for natural gas
or 2,520 BTU per cubic foot for propane).
Note: The fuel supplier or utility should be consulted to
confirm that sufficient volume and normal pressure is
provided to the building at the discharge side of the
gas meter or supply pipe.
6.8 Gas Pipe Drip Leg and Shut-off Valve
1. Install a gas pipe drip leg on each water heater to prevent
dirt, condensation, or debris from entering the gas inlet.
Drip Leg
2. Local codes may require multiple units to have a full size
drip leg on the main gas supply line and one on each unit.
3. The drip leg should have a removable clean-out cap.
4. The gas pipe must not be supported by the drip leg.
5. Following local building codes when selecting and installing
a shut-off valve.

iN401 - iN501 GasConnection 16
May2019-Revision00
6. Local codes may require multiple units to have a shut-off
valve on the main gas supply line and one on each unit.
6.9 Connecting Gas Line to Unit
Note:Always clean the inside of the gas line of any dirt or
debris before connecting the piping to the unit.
Main Supply
Line
Drip
Leg
Manual
Shut-off
Valve
Main Supply
Line
Drip
Leg
Drip
Leg
Drip
Leg
Drip
Leg
Manual
Shut-off
Valve
Manual
Shut-off
Valve
Manual
Shut-off
Valve
Manual
Shut-off
Valve
1. Install a 4-5/8” OD flanged steel coupling and gasket with
a short piece of 1-1/4” NPT black pipe.
2. Install a manual shut-off valve as described in “6.8 Gas
Pipe Drip Leg and Shut-off Valve” on page 15
Union
Shut-off
Valve
3. Install a drip leg in “6.8 Gas Pipe Drip Leg and Shut-off
Valve” on page 15.
4. Continue installing pipe to reach the main gas supply
connection.
5. Test all gas pipe connections.
a. All the gas pipe connections should be tested as
prescribed in NFPA 54.
b. In multiple unit applications, each unit should be
isolated before testing any piping system may exceed
the allowable pressure of 14.0” W.C..
NOTICE
Do not fire (operate) the water heater until all connections
have been completed and the heat engine is filled with
water.