Bock Water heaters OT600-A Service manual

WARNING
Improper installation, adjustment, alteration,
service or maintenance can cause serious injury
or property damage. Refer to this manual. For
assistance or additional information, consult a
qualified installer or service agency.
WARNING
Install in accordance with all local codes. In the
absence of local codes, refer to NFPA 54 or CSA
B149.1.
CAUTION
The recommended temperature for normal
residential use is 120°F. The dial on the aquastat
does not always reflect the out-coming water
temperature and it could occasionally exceed
120°F. Variation in out-coming temperature could
be based on factors including but not limited to
usage patterns and type of installation.
WARNING
Hotter water increases the risk of scald injury.
Before adjusting the water temperature setting,
read this instruction manual. Temperatures at
which injury occurs vary with the person’s age
and the length of exposure. The slower reaction
time of children, elderly or physically or mentally
challenged persons increases the scalding hazard
to them. It is recommended that lower water
temperatures be used where these exposure hazards
exist. Households with small children or invalids
may require a temperature setting less than 120°F
to prevent accidental contact with hot water.
To produce less than 120°F, use point-of-use
temperature limiting devices.
If higher water temperature is needed in part of
the water system, automatic temperature limiting
devices must be used on all lines to water taps.
WARNING
Water heater blankets may restrict air flow to the
water heater and cause fire, asphyxiation, personal
injury or death.
THIS MANUAL HAS BEEN PREPARED TO
ACQUAINT YOU WITH THE INSTALLATION,
OPERATION, AND MAINTENANCE OF YOUR
WATER HEATER AND TO PROVIDE IMPORTANT
SAFETY INFORMATION.
Read all instructions thoroughly before attempting
installation or operation of your water heater. Keep
these instructions for future reference.
Local plumbing and electrical codes must be
followed in the installation of this water heater.
In the absence of a local code use the UNIFORM
PLUMBING CODE and the NFPA Code. Local codes
may supersede instructions in this installation
manual.
These instructions are a guide for the correct
installation of the water heater. The manufacturer
will not be liable for damages caused by failure to
comply with the installation and operating instruc-
tions outlined on the following pages.
DO NOT use this appliance if any part has been
under water. Immediately call a qualified service
technician to inspect the appliance and to replace
any part of the control system and any gas control
which has been under water.
FAILURE TO FOLLOW THESE INSTRUCTIONS OR
ALL APPLICABLE BUILDING CODES
AND REGULATIONS VOIDS THE WARRANTY ON
THIS WATER HEATER.
Warranty, Registration Card and Parts List are included.
Owner: Please remember to return the Registration Card!
To the Consumer:
Please read these and all component
instructions and keep for future reference.
To the Installer:
Please attach these instructions
next to the water heater.
Rev0 05/2022
23404 EN
Installation and Operation Instructions Manual
Models: OT600-A, OT700-A, OT800-A, OT900-A
High Efficiency Commercial Gas Water Heater
–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 neigh-
bor’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.
WARNING: If the information in these instructions is not followed exactly, a
fire or explosion may result causing property damage, personal injury or death.

IMPORTANT SAFETY INSTRUCTIONS
The proper installation, use and servicing of this water heater is very
important to your safety and the safety of others.
This is the safety alert symbol. Statements following this symbol contain
important safety information. Obey all safety messages that follow this
symbol to avoid possible injury or death.
Important safety information will be preceded by the safety alert symbol
and the words DANGER, WARNING, CAUTION, OR NOTICE.
DANGER indicates an imminently hazardous situation which, if not
avoided, will result in serious injury or death.
WARNING indicates a potentially hazardous situation which, if not
avoided, could result in serious injury or death.
CAUTION indicates a hazardous situation which, if not avoided, could
result in minor or moderate injury.
NOTICE calls attention to observe a specified procedure.
SAVE THESE INSTRUCTIONS
DANGER
Water heaters utilizing Liquefied Petroleum gas (LP) are different from
natural gas models. A natural gas heater will not function safely on LP gas
and vice versa. To avoid possible equipment damage, personal injury or
fire: DO NOT connect this water heater to a fuel type not in accordance
with the rating label. These units are only certified for a single fuel type.
DANGER
Failure to properly install the vent and combustion air intake system as
outlined in this manual can result in unsafe operation of the water heater.
To avoid the risk of fire, explosion, or asphyxiation from carbon monoxide,
never operate this water heater unless it is properly vented and has
adequate air supply for combustion and dilution of flue gas. Be sure to
inspect the system for proper installation at initial start-up; and at least
annually thereafter. See the Maintenance section for more information.
Page 2

TABLE OF CONTENTS
Section I: Specifications .............................................4
Section II: General Information ........................................5
Section III: Pre-Installation ...........................................11
Section IV: Installation ..............................................14
Section V: Operation ...............................................42
Section VI: Maintenance ............................................46
Section VII: Troubleshooting .........................................50
Section VIII: Parts List ...............................................56
Section IX: Warranty ...............................................60
Page 3

Model
Rated Storage
Capacity, GAL (L)
Rated Maximum
Input, Btu/hr (kW)
Thermal Efficiency
(%) @ Max. Input
Recovery @ 100°F
rise, GAL/HR (L/HR)
A C
E
G
HOT (NPT)
Rated Minimum
Input, Btu/hr (kW)
Thermal Efficiency
(%) @ Min. Input
1st Hr. Delivery @
100°F rise, GAL (L)
B
D
F
COLD (NPT)
Table 1: Dimensions
Page 4
SECTION I: SPECIFICATIONS
Figure 1: All Models
DIMENSIONS, INCHES (cm)
NOTE: * denotes fuel type, N or LP, and sufx “-A” denotes ASME
For HIGH ALTITUDE models, the following additional sufxes are dened as:
“-H28” = Approved for altitudes greater than 2,000 up to 7,800 FT
For natural gas:
MINIMUM GAS SUPPLY PRESSURE (at gas control) = 4.0” W.C. (dynamic)
MAXIMUM GAS SUPPLY PRESSURE (at gas control) = 14” W.C. (static or dynamic)
Air Intake (PVC)
Gas (NPT)
Exhaust
Vent (PVC)
Shipping Weight,
LBS (kg)
For LP gas:
MINIMUM GAS SUPPLY PRESSURE (at gas control) = 8” W.C. (dynamic)
MAXIMUM GAS SUPPLY PRESSURE (at gas control) = 14” W.C. (static or dynamic)
Note: Dynamic pressure is measured while gas is owing and static pressure is measured while gas is
not owing.
All Bock products meet or exceed current ASHRAE standards.
These products are design certied by UL (Underwriters Laboratories) and meet ANSI Z21.10.3/CSA 4.3
requirements for operation up to 180°F (82°C) as a Category IV water heater.
Approved for use as a direct vent automatic instantaneous water heater.
RECIRCULATION
RETURN (NPT)
CONNECTION SIZES
H
OT600*-A
130
(492)
600,000
(175)
140,000
(41)
98
99
706
(2,675)
797
(3,017)
78
(199)
34
(86)
68
(173)
15
(38)
13
(33)
67
(170)
78
(198)
42
(106)
80
(203)
83
(211) 2” 2” 1” 2” 6” 6” 1,700 (773)
OT700*-A 700,000
(205)
98 824
(3,121)
915
(3,464)
OT800*-A 800,000
(235)
98 941
(3,567)
1,032
(3,907)
OT900*-A 900,000
(264)
98 1,059
(4,013)
1,150
(4,353)
I
J

Page 5
APPROXIMATE
TEMPERATURE/TIME
RELATIONSHIPS TO
SCALDING
120°F (49°C) More than 5 minutes
125°F (52°C) 1 1⁄2 to 2 minutes
130°F (54°C) About 30 seconds
135°F (57°C) About 10 seconds
140°F (60°C) Less than 5 seconds
145°F (63°C) Less than 3 seconds
150°F (66°C) About 1 1⁄2 seconds
155°F (68°C) About 1 second
Table 2: Scald Temperature/Time Relationships
SECTION II: GENERAL INFORMATION
WHEN YOU RECEIVE YOUR NEW WATER HEATER
Check the new equipment to see if all components are in good condition. If damage is
observed or parts appear to be missing, contact your wholesaler.
WATER TREATMENT/FILTRATION
In areas where poor water conditions are suspected (i.e. lime, iron, and other minerals), it is
essential that the water be tested and appropriate action taken to prevent damage to the
water heater and ensure the quality of the water.
TEMPERATURE CONTROL
The water heater is equipped with a main operating control that manages the temperature
regulating and limiting functionality. For domestic hot water, the proper temperature setpoint
is 120°F. For commercial applications, the maximum approved temperature setpoint is 180°F.
Sensors in the top of the tank measure water temperature. The control constantly compares
the sensor values to the temperature setpoint, and controls the burner power (on/off) and
modulation accordingly.
The manual reset, temperature limiting safety function is managed by the main operating
control. In the event that the tank temperature sensor reads 190°F, the control will shut off
all gas to the water heater. Manually reset the control to allow the heater to resume normal
operation. Should overheating occur and the gas supply fails to automatically lockout,
manually flip off the power switch.
The temperature setpoint is factory set at 120°F. If hotter water is required a tempering device
or anti-scald device must be installed at the domestic hot water outlet of the heater or at the
point of use. Table 2 details the approximate relationship of water temperature and time with
regard to scald injury. It is important for the user to understand the necessity of tempering or
anti-scald devices when using hotter water in domestic water heating systems.
CAUTION: Hot water in excess of 120°F can cause scalding!
Bock recommends a tempering valve or anti-scald valve be installed and used according to
the manufacturer’s directions to prevent scalding. Many state and local codes now require
installation of these devices. Point of use temperature may be hotter than the setting on the
water heater thermostat. The tempering valve or anti-scald valve will ensure potable
water temperatures at the desired set point with a higher degree of accuracy.
Shipping Weight,
LBS (kg)

SECTION II: GENERAL INFORMATION
ANODE RODS
The water heater is supplied with a factory installed powered anode system to prevent corrosion of
internal tank components. Specifically, the type of anode system that is used is an impressed-cur-
rent anode system. This system uses a power supply that regulates the protective current output
based on actual conditions inside the tank. The anode rods in the tank are not consumed over time
and, therefore, do not need to be removed and inspected. Refer to the Maintenance section of this
manual for periodic inspection instructions for the powered anode system.
NOTICE TO THE OWNER: The water heater must be connected to the power supply for the
powered anode system to operate. DO NOT DISCONNECT THE WATER HEATER FROM THE
POWER SUPPLY FOR AN EXTENDED PERIOD OF TIME. WITHOUT POWER, THE ANODE SYSTEM
WILL NOT BE CAPABLE OF PROVIDING CORROSION PROTECTION. When the power switch to
the right of the display is OFF and there is a connection to the power supply, the powered
anode system will still function. If the water heater must be disconnected from the power
supply for an extended period, the tank must be drained. Refill the tank prior to reconnect-
ing the water heater to the power supply.
CAUTION
Hydrogen gas is produced in a hot water system served by the heater that has not been
used for a long period of time (2 weeks or more). Hydrogen gas is extremely flammable. To
reduce the risk of injury under these conditions, it is recommended that a hot water faucet
be opened for several minutes before using any electrical appliance connected to the hot
water system. When hydrogen is present, there will probably be an unusual sound such as
air escaping through the pipe as the water begins to flow. There should be no smoking or
open flame near the faucet at the time it is open.
TEMPERATURE AND PRESSURE RELIEF VALVE (T&P)
CAUTION
To reduce the risk of excessive pressures and temperatures in this water heater, install
temperature and pressure protective equipment required by local codes and no less than
a combination temperature and pressure relief valve certified by a nationally recognized
testing laboratory that maintains periodic inspection of production of listed equipment or
materials, as meeting the requirements for Relief Valves and Automatic Gas Shutoff Devices
for Hot Water Supply Systems, ANSI Z21.22. This valve must be marked with a maximum
set pressure not to exceed the marked maximum working pressure of the water heater.
Install the valve in an opening provided and marked for this purpose in the water heater,
and orient it or provide tubing so that any discharge from the valve exits only within 6
inches above, or at any distance below, the structural floor, and does not contact any live
electrical part. The discharge opening must not be blocked or reduced in size under any
circumstances. No valve is to be added between the relief valve and tank.
CAUTION
Scalding injury and/or water damage can occur from either the manual lifting of the
lever or the normal operation of the T&P valve if it is not piped to a proper drain. If the
valve fails to flow water or reseat, call your plumber.
The T&P valve is factory supplied but not factory installed. Take the T&P valve, which has a
plastic lined nipple loosely connected, from the accessories box. Disconnect the pipe nipple
and apply sealant to both ends, then re-connect the fitting and valve. Install the pair into the
tank fitting on the top right side of the tank which is covered by an orange sticker directing
correct installation of the T&P Valve. After hand tightening the valve apply 4-6 additional
rotations to the valve using a large crescent wrench or pipe wrench. Grip the valve body across
the provided flats, taking care not to damage threads or labeling. Before operation inspect the
T&P valve threaded connections for leaks. Do not install any other fitting, nipple, or valve in
this location other than the T&P valve and nipple supplied. A discharge drain tube must be
installed (responsibility of the installer) and shall terminate plain, not threaded, 6 inches above
the floor drain. The drain tube material must be approved for temperatures of 120°F or greater
and a pressure of 150 PSI or greater.
Page 6

SECTION II: GENERAL INFORMATION
LOW WATER CUTOFF
A low water cutoff device is optional, and available for factory or field installation. For field
installation, reference the control panel figure in Section VIII (Parts List) for the location of
the device and the 24V power supply. Reference the wiring diagrams in Section IV (Installa-
tion) for proper connections. The yellow and pink wires for connection from the main control
to the low water cutoff control are labeled “LWCO.” When a low water cutoff is not present,
the yellow and pink wires are connected to close the circuit. Disconnect these wires and make
the yellow-to-yellow and pink-to-pink connections to the low water cutoff wiring harness.
BACKFLOW PREVENTER (CLOSED SYSTEM)
Some local municipal codes and ordinances require the use of these devices on potable
(domestic) water lines. Where backflow preventers, check valves, or pressure regulating valves
are required, it will be necessary to install a thermal expansion tank (designed for use with
potable water) in order to prevent pressure build up in the water heater and associated piping,
which could cause the T&P valve to discharge. Follow the expansion tank manufacturer’s
recommendations when selecting a tank for your hot water system. The expansion tank pressure
shall equal the water heater system pressure prior to initial warm up. Periodic relieve valve
discharges may be a result of thermal expansion in a closed water supply system. Contact the
water supplier or local plumbing inspector for information about thermal expansion tanks.
Note: Working pressure of the water heater is 150 PSI. Do not exceed 150 PSI.
CONDENSATION
Condensation of flue gases will occur in the exhaust vent and portions of the heat exchanger
during burner operation. Condensate is considered acidic based on its typical pH range of
3.5 to 3.8 on a scale of 0 to 14 (a pH of 7 is neutral). Some installations may require the use
of a condensate neutralizer kit to reduce the acidity of the condensate prior to it entering the
building’s drainage system. When possible, locate a floor drain in close proximity to the water
heater to minimize the length of the drain line. The water heater is supplied with a condensate
trap assembly that must be installed to the water heater before the exhaust vent is connected.
Horizontal sections of the exhaust vent shall slope upward away from the water heater a minimum
of 1/8” per foot. This will allow the condensate in the vent to run back to the condensate drain
on the water heater. In some instances, condensate may form in the intake piping during periods
following burner operation. Horizontal sections of air intake piping shall slope downward away
from the water heater a minimum of 1/8” per foot. A condensate drainage tube shall be installed
on the intake piping (at the factory provided tee.)
See Section IV: Installation / Vent and Combustion Air Intake / Condensate Elbow Assembly and
Section IV: Installation / Vent & Combustion Air Intake / Intake Drain for installation details.
Page 7

Page 8
SECTION II: GENERAL INFORMATION
SEISMIC RESTRAINT
Regions of the United States and Canada that are considered earthquake zones require that
the water heater is properly braced to avoid movement or falling during a seismic event.
Figures 2 and 3 show common approaches to bracing and are provided only as concepts.
Refer to state and local codes and follow specific instructions for correct installation.
LOWER STRAP
UPPER STRAP
METAL FRAMING
UPPER STRAP
LOWER STRAP
WALL
Figure 2: Seismic Restraints to Support Framing
LOWER STRAP
UPPER STRAP
METAL FRAMING
UPPER STRAP
LOWER STRAP
WALL
Figure 3: Seismic Restraints to Wall

Page 9
SECTION II: GENERAL INFORMATION
BURNER RELEASE (DRAFT SYSTEM INTERLOCK)
The Burner Release setting provides the option to connect the water heater to a mechanical
draft control. Mechanical draft controls shall only be utilized when vent lengths exceed the
limits specified in this manual. Consult Bock Water Heaters and the manufacturer of the
mechanical draft system for recommendations on pressure sensor location and setpoint in
the exhaust vent. Note: An Enervex EBC24 modulating fan control was referenced for feature
design.
To achieve a proper interlock between the water heater and the draft control, all wiring shall
be in accordance with both the draft control and water heater installation manuals. The
interlock strategy will utilize a dry set of contacts on the water heater.
Two pairs of wires are needed for the connections at the water heater and are located at the
850IF control on the control panel. The red (“R”) pair, labeled “Call for Heat Output”, provides
a normally open dry contact that closes when a call for heat (i.e., Demand) is initiated by
the water heater’s main operating control. The red pair will typically be used in series to
switch the hot side of a low voltage supply to an input on the draft control. The black/white
(“BK/W”) pair, labeled “Burner Release Input,” is controlled by a volt free contact on the draft
control and typically connected to an output on the draft control. This circuit is closed when
the draft control has satisfied its safeties and is allowing the water heater to proceed with an
ignition sequence. Refer to the wiring diagrams in this manual for wire pair locations and the
building draft control manual for detailed connection diagrams.
To adjust the Burner Release setting via the display, perform the following steps:
1) Navigate to the Settings tab. Select the
Advanced option, and then select Burner
Release.
2) The default setting for Burner Release is
ON. This setting automatically initiates the
burner lighting sequence during a call for
heat. To change the setting, press the Burner
Release button at the bottom of the screen.
3) A new window appears where the setting
may be changed. Select the new setting and
press OK. Verify that the setting is correct on
the Burner Release screen.
4) If Burner Release was changed to OFF,
the burner ignition sequence will only start
when the mechanical draft control releases
the burner for operation.

Page 10
SECTION II: GENERAL INFORMATION
HIGH LIMIT COMMISSIONING
To prove functionality, the temperature limiting safety function may be tested by selecting
the High Limit Commissioning Test via the display. The high limit temperature is factory set
at 190°F. For safety reasons, the factory set high limit will automatically lower to equal the
operating setpoint when the test is started. To conduct the High Limit Commissioning Test,
perform the following procedure.
1) The water heater must be in “DEMAND”
before starting this test. To create a demand for
hot water open a faucet, or increase the setpoint
temperature by 10°F.
2) Using the display, navigate to the Settings
tab. Select the Test option, and then select High
Limit Commissioning Test.
3) With the water heater running in DEMAND,
press the Start button from the High Limit
Commissioning Test screen.
4) Return to the Home screen and a yellow message will appear below the power bar that
reads, “High Limit Commissioning Test In Progress.”
5) When the sensor temperature equals the setpoint, gas flow to the burner will stop and the
blower will enter post purge. The water heater will be in “LOCKOUT ERROR” and the error
code “A18 – MAX TEMP ERROR” shall be displayed.
6) Press the Reset button to exit the test mode and resume normal operation.

Page 11
SECTION III: PRE-INSTALLATION
LOCATION
CAUTION
This water heater must be located in an area where leakage of the tank, water line
connections, or the temperature and pressure relief valve will not result in damage to the
area adjacent to the water heater or to lower floors of the structure. When such location
cannot be avoided, a suitable drain pan must be installed under the water heater. The
drain pan depth must be suitable for draining and collecting water. The drain pan can
be purchased from your plumbing professional. The drain pan must be piped to an
adequate drain and all drain piping must be at least 0.75” in diameter and pitched for
proper drainage.
CAUTION
DO NOT store or use gasoline or other flammable, combustible, or corrosive vapors and/
or liquids in the vicinity of the water heater or any other appliance.
IF YOU SMELL GAS:
• DO NOT try to light any appliance.
• DO NOT touch any electric switch; do not use any telephone in your building.
• Immediately call your gas supplier from a telephone in another building. Follow your
gas supplier’s instructions.
• If you cannot reach your gas supplier, call the fire department.
DO NOT OPERATE THE APPLIANCE UNTIL THE LEAKAGE IS CORRECTED!
CAUTION
Do not drop water heater or lay heater down on its side. Move the water heater into
position with a pallet jack or forklift rated for at least 1700 lbs. The openings on the
bottom of the tank are designed to be compatible with a standard pallet jack.
CAUTION
If the water heater is installed directly on carpeting, the water heater shall be installed
on a metal or wood panel extending beyond the full width and depth of the water
heater by at least 3 inches (76.2 mm) in any direction or, if the water heater is installed
in an alcove, the entire floor shall be covered by the panel. The panel must be strong
enough to carry the weight of the heater when full of water.
Locate the heater so it is not subject to physical damage from moving vehicles or flooding.
Do not locate the water heater in a room where swimming pool chemicals or large quantities
of water softener salt are kept. Installing a water heater in this environment will result in
premature failure of tank and burner components due to corrosion caused by these elements
diffusing into the air.
NOTE: To comply with the installation requirements in NSF Standard 5, the bottom of this
water heater must be sealed to the floor with a silicone based sealant. Plug the 4 openings
designed for use with forklifts/hand trucks with a suitable sealing plug, such as the Bock
supplied metal covers which attach with magnetic latches to the fork openings.
The water heater can be installed on combustible or non-combustible flooring. Maintain
clearances specified in this manual and in accordance with the National Fuel Gas Code (NFPA
54, ANSI Z223.1) unless otherwise directed by state and local code requirements. Locate the
water heater such that plastic vent pipe lengths and the number of connection fittings are
minimized. Adequate downward pitch is required on the condensate line for proper drainage.
See Section IV: Installation / Vent & Combustion Air Intake / Condensate Elbow Assembly for
details. If pitch is insufficient and the use of a low profile condensate pump is not feasible, the
heater needs to be placed on a concrete slab to increase the distance between the condensate
line connection and the floor.

SECTION III: PRE-INSTALLATION
GAS SUPPLY LINE
Prior to installation, contact your local gas utility to confirm that sufficient gas service is available
for the water heater. The gas meter must have adequate capacity to supply the rated maximum gas
input of the water heater in addition to other gas fired equipment connected to the meter.
Minimum Gas Supply Pressure
The gas supply must be capable of maintaining a minimum pressure at the inlet of the gas control
during water heater operation at maximum input. The pressure will be lowest at the gas control
during water heater operation (i.e. gas is flowing) at maximum input. For natural gas models,
during operation at maximum input, the supply pressure at the gas control must be at least 4.0”
W.C. For LP gas models, during operation at maximum input, the supply pressure at the gas
control must be at least 8” W.C.
Refer to Table 3 for gas supply line sizing. The table shows maximum input in thousands of BTU’s
per hour for various pipe sizes and lengths. The table assumes gas supply pressures of 14” W.C. or
less and a pressure drop of 0.3” W.C.
At minimum, use 1-1/2” gas supply pipe for model OT600.
For models OT700-900, use a minimum of 2” pipe.
Maximum Gas Supply Pressure
The gas supply pressure shall never be greater than 14” W.C.
Refer to Section IV: Installation / Gas Connections for further installation instructions.
Page 12
Figure 4: Minimum Clearance From Combustibles Figure 5: Recommended Minimum Access Clearances
Nominal
Iron Pipe
Size
(inches)
Internal
Diameter
(inches)
Length of Pipe (feet)
10 20 30 40 50 60 70 80 90 100 125 150 175 200
1 1/4 1.380 1,050 730 590 500 440 400 370 350 320 305 275 250 225 210
1 1/2 1.610 1,600 1,100 890 760 670 610 560 530 490 460 410 380 350 320
2 2.067 3,050 2,100 1,650 1,450 1,270 1,150 1,050 990 930 870 780 710 650 610
2 1/2 2.469 4,800 3,300 2,700 2,300 2,000 1,850 1,700 1,600 1,500 1,400 1,250 1,130 1,050 980
3 3.068 8,500 5,900 4,700 4,100 3,600 3,250 3,000 2,800 2,600 2,500 2,200 2,000 1,850 1,700
4 4.026 17,500 12,000 9,700 8,300 7,400 6,800 6,200 5,800 5,400 5,100 4,500 4,100 3,800 3,500
Table 3: Gas Supply Line Capacity
0"
COMBUSTIBLE FLOORING
0"
0"
0"
SECTION B-B
6in
0in 0in
SECTION N-N
COMBUSTIBLE WALLS
24"
8"
12"
COMBUSTIBLE OR NON-COMBUSTIBLE WALLS
COMBUSTIBLE
OR NON-
COMBUSTIBLE
FLOORING
24" FOR ACCESS IN FRONT
OF WATER HEATER
0
SECTION C-C
Minimum clearance from combustible material is 0” for the sides, top, and back of this water
heater, as shown in Figure 4. This water heater is approved for installation in an alcove with
the clearances shown in Figure 4. For ease of access and proper maintenance, the clearances in
Figure 5 are recommended.

Page 13
SECTION III: PRE-INSTALLATION
COMBUSTION AND VENTILATION AIR
The water heater can be installed to utilize combustion air from either inside or outside the
building. Refer to “Section IV: Installation” for detailed venting specifications. If indoor air is
used for combustion air it is imperative that the room has an adequate air supply. Inadequate
air supplies may lead to unsafe levels of carbon monoxide (CO) and excessive levels of soot.
See NFPA 54 or the discussions of “Unconfined Space” and “Confined Space” below. In
addition, poor ventilation will also result in hot spots around the heater. Temperatures over
90°F near the water heater generally indicate a lack of ventilation.
UNCONFINED SPACE
Unconfined space is defined by NFPA 54 as a space with a volume greater than 50 cubic feet
(during typical use) per 1000 BTUH of the total combined input of all fuel burning appliances
in the space. Rooms leading directly to the installation space through doors that cannot
be closed can be considered part of the space. Exception: Buildings with full vapor barriers,
tight doors and windows or air infiltration rates of less than 0.35 air changes per hour will be
considered a confined space and require additional air supplies.
CONFINED SPACE
Confined space is defined by NFPA 54 as a space with a volume less than 50 cubic feet (during
typical use) per 1000 BTUH of the total combined input of all fuel burning appliances in the
space. Buildings or rooms of unusually tight construction are also considered a confined space.
See “Unconfined Space: Exception”.
When installing fuel burning appliances in a confined space, air must be supplied to that
space from either inside or outside of the building as conditions allow.
A. Inside Air Supply: A confined space shall be provided with two permanent openings; one
within 12 inches of the top and one within 12 inches of the bottom of the enclosure. These
openings shall lead directly to room(s) of sufficient volume so that the combined volume of
all the space meets the criteria for unconfined space. Each opening shall have a minimum
free area of 1 square inch per 1000 Btu/hr of the combined total input of all fuel burning
appliances in the space. Each opening shall have an area of not less than 100 square inches or
a minimum dimension of not less than 3 inches.
B. Outside Air Supply: Confined spaces shall be provided with two permanent openings; one
within 12 inches of the top and one within 12 inches of the bottom of the enclosure. These
openings shall communicate directly, or by ducts, with the outdoors or spaces that
communicate with the outdoors.
1.) Leading directly to the outside or through vertical ducts: Each opening shall have a
minimum free area of one square inch per 4000 Btu/hr of total input rating of all equipment
in the enclosure.
2.) Leading to outside through horizontal ducts: Each opening shall have a minimum free
area of one square inch per 2000 Btu/hr of total input rating of all equipment in the enclosure.
Note: All ducts shall have the same cross sectional area as the free area of each opening to
which they connect. The minimum dimensions of all ducts shall not be less than three inches.
Powered combustion air supplies are also commercially available and may be used.
LOUVERS & GRILLES
In calculating the free area of an opening, consideration must be given to the blocking effects
of louvers or grilles protecting the opening. Any screens used must be no finer than 1⁄4inch
mesh. If the free area of a louver or grille is known, this should be used in calculating the size
of opening required. If free area is unknown, it may be assumed that wood louvers will have
20 to 25% free area and metal louvers and grilles will have 60 to 75% free area. Louvers and
grilles should be fixed in the open position or interlocked with the equipment so that they
open automatically during equipment operation.

SECTION IV: INSTALLATION
VENT & COMBUSTION AIR INTAKE
DANGER
Failure to properly install the vent and combustion air intake system as outlined in this
manual can result in unsafe operation of the water heater. To avoid the risk of fire,
explosion, or asphyxiation from carbon monoxide, never operate this water heater
unless it is properly vented and has adequate air supply for combustion. Be sure
to inspect the system for proper installation at initial start-up; and at least annually
thereafter. See the Maintenance section for more information.
NOTICE
Failure to comply with orientation and minimum spacing requirements between
exhaust vent and air intake terminals may lead to cross-contamination of combustion
air. Cross-contamination may lead to nuisance lockouts from ignition or flame failures
and will increase maintenance on parts such as the flame rod.
In some cases cross contamination may occur even when orientation and minimum
spacing requirements are followed. Therefore attention must be given to the unique
conditions at every jobsite to avoid the possibility of exhaust gas entering the air intake.
The water heater venting and combustion air intake can be installed as a power direct vent
system (combustion air from outside the building) or power vent system (combustion air from
inside the building). Vertical or horizontal (side-wall) configurations may be used.
The venting system shall be installed in accordance with these instructions, and, where
applicable, the instructions of the venting system manufacturer.
Note: If air from inside the building will be used for combustion air, the require-
ments in Section III, “Unconfined Space” must be met.
A power direct vent system terminates in a 2-pipe configuration. The vent and intake
equivalent lengths must comply with minimum and maximum lengths specified in Table 4.
The water heater is supplied with a pre-assembled PVC condensate assembly that must be
installed to the condensate drain nipple. See instructions in Section IV: Installation / Vent &
Combustion Air Intake / Condensate Elbow Assembly.
For direct vent systems, a 6” PVC 90° standard bend elbow is supplied and must be used
as the air intake termination fitting. For direct vent systems that exhaust horizontally, use
the supplied 6” PVC Tee as the exhaust termination. For direct vent systems that exhaust
vertically, the exhaust vent should be terminated as a straight pipe.
For power vent sytems, the supplied 4” PVC 90° standard bend elbow must be used as the
air intake termination fitting. Install the 4” elbow directly to the factory installed 4” pipe.
For power vent systems that exhaust horizontally, use the supplied 6” PVC Tee as the exhaust
termination fitting. For power vent systems that exhaust vertically, the exhaust vent should
be terminated as a straight pipe.
All vent length measurements specified in this manual are in addition to the pre-assembled
piping and supplied assemblies and fittings. Equivalent pipe lengths shall not be greater than
the maximum lengths (or less than minimums) given in Table 4. See the notes under Table 4
for additional information pertaining to direct vent or power vent system lengths.
Note: DO NOT connect the water heater to an existing vent or chimney. It must be
vented separately from all other appliances.
Page 14

SECTION IV: INSTALLATION
The following materials are approved for use as the vent and combustion air intake piping:
• PVC (DWV, ASTM-D2665 or CSA B181.2)
• PVC (Schedule 40, ASTM-D1785 or CSA B137.3)
• PVC (SDR Series, ASTM-D2241 or CSA B137.3)
• CPVC (Schedule 40, ASTM-F441 or CSA B137.3)
• CPVC (SDR Series, ASTM-F442)
• ABS (Schedule 40, DWV, ASTM-D2661 or CSA B181.1)
• AL29-4C Stainless Steel
• PVC IPEX 1738 (UL 1738, ASTM D2665)
In Canada, check local codes to ensure that SDR series is approved for use. SDR is not
approved for all installations in Canada.
The following materials are approved for use for the fittings in the vent and combustion
air intake systems:
• PVC (Schedule 40 DWV, ASTM D2665)
• CPVC (Schedule 40, ASTM F438)
• ABS (Schedule 40 DWV, ASTM D2661)
• AL29-4C Stainless Steel
• PVC IPEX 1738 (UL1738, ASTM D2665)
The use of cellular core PVC (ASTM F891), cellular core CPVC, or Radel® (polyphenylsul-
fone) in non-metallic vent pipe and systems is prohibited. Covering non-metallic vent
pipe and fittings with thermal insulation is prohibited.
Page 15
NOTICE
Installations in Canada must conform to the requirements of CSA B149 code. Plastic
vent systems must be assembled with pipe, fittings, cements, and primers listed to
ULC S636. Components of this listed system shall not be interchanged with other vent
systems or unlisted pipe/fittings. In Canada, the primer and cement must be of the
same manufacturer as the vent system; do not mix primers and cements from one
manufacturer with a vent system from a different manufacturer. The supplied plastic
pipe/fittings are certified as part of the water heater.

Page 16
NOTE: The equivalent straight pipe length of a 90°, 1/4 standard bend elbow and
a 45°, 1/8 standard bend elbow is 5 feet and 2.5 feet, respectively. DO NOT use
short bend elbows.
NOTE: An elbow used as an exhaust vent termination fitting must be included
when determining the total number of elbows.
Figure 6: Establishing the Intake and Exhaust Vents
SECTION IV: INSTALLATION
Minimum and Maximum System Lengths
The water heater should be located such that plastic vent pipe lengths and the number
of connection fittings are minimized. Minimum and maximum equivalent pipe lengths
for the vent and combustion air intake systems are given in Table 4. 6” diameter piping
must be used. The water heater is provided with a 6” female PVC connection for the air
intake and a 6” female PVC connection for the exhaust vent. For ease of installation and
potential future inspection, a 4” flexible coupling is used as the first connection on the
blower.
DO NOT use less than 6” diameter plastic pipe and DO NOT use unequal sizes except as
shown to increase from 4” to 6” diameter at the point of connection to the water heater.
Figure 6 shows the proper connections to increase from 4” to 6” plastic pipe on the
intake, and how to establish the exhaust venting with the factory supplied assembly.
Prior to connecting the exhaust assembly, apply a bead of silicone around the inside of
the straight coupling. For maximum durability and sealing, use a high heat silicone caulk
for direct vent appliances (rated for at least 150°F). Apply a bead around the end of the
exhaust pipe as well. Push the end of the coupling over the exhaust pipe as far as the pipe
allows.
P
DETAIL P
SCALE 1 : 16
EXHAUST ASSEMBLY
(FACTORY SUPPLIED)
APPLY BEAD HIGH TEMP
SILICON CAULK ALL THE
WAY AROUND PRIOR TO
PUSHING ON THE
EXHAUST ASSEMBLY.
G
DETAIL G
SCALE 1 : 16
4" X 6" INCREASER
(FACTORY SUPPLIED)
4" FLEXIBLE COUPLING
(FACTORY SUPPLIED"
AIR INTAKE
H
M
DETAIL H
SCALE 1 : 16
6" 22.5° ELBOW
(FACTORY SUPPLIED)
6" PVC STRAIGHT COUPLING
(FACTORY SUPPLIED)
6" STRAIGHT PIPE
(FACTORY SUPPLIED)
K
DETAIL K
SCALE 1 : 16
SEAL WITH
SILICONE CAULK
ALL THE WAY
AROUND
CONNECTION.
SEAL
CONNECTION
WITH PVC PRIMER
AND CEMENT.
DETAIL M
SCALE 1 : 16
EXHAUST PIPE ELBOW
UNION 'B'
3/4" FEMALE NPT
EXHAUST VENT
EXHAUST VENT
)

Page 17
SECTION IV: INSTALLATION
Table 4: Minimum and Maximum Vent and Air Intake Pipe Lengths (6” Pipe)
1For direct vent, equivalent length is measured between the 6” pipe connection on the water
heater and the required 90° elbow termination fitting.
2Equivalent length is measured between the factory supplied exhaust assembly and the
required 6” PVC Tee termination fitting. For vertical exhaust, equivalent length is measured after
the factory supplied exhaust assembly to the end of the vertical pipe.
†Shown as a balanced system. Vent length may exceed air intake length if total combined length
does not exceed 200 ft.
Intake length cannot exceed exhaust length.
Model(s) Fuel
Type
Vent
Arrangement
Minimum Equivalent Pipe
Length (per pipe run)
Maximum Equivalent Pipe
Length (per pipe run)
Air Intake1(ft) Vent2(ft) Air Intake1(ft) Vent2(ft)
OT600, OT700,
OT800, OT900
NAT or
LP
Direct Vent 20 20 100†100†
Power Vent 0 20 0 200

Page 18
SECTION IV: INSTALLATION
The vent and combustion air intake systems must be sufficiently supported along
vertical and horizontal sections. At minimum, it is recommended that a support is placed
along the vent or air intake piping every 4 feet. For horizontal systems, the first support shall
be located immediately adjacent to the first 90-deg. elbow following the vertical section
connected to the water heater. The support method should act to isolate the vent and
combustion air intake piping from floor joists or other structural members to reduce transmis-
sion of noise and vibration.
NOTE: Do not support, pin, or secure the vent and combustion air intake pipe in a
way that restricts the normal thermal expansion and contraction of the venting
material.
For replacement installations, thoroughly inspect the existing vent and combustion air intake
systems prior to installing the new water heater. The following steps shall be taken to properly
inspect the existing vent system:
• Verify that the materials as specified in this manual have been used.
• Verify the maximum and minimum vent and combustion air intake equivalent lengths and
terminal clearances meet the specifications in this manual.
• Inspect the vent and combustion air intake systems for cracking. Pay close attention to joints
between elbows and straight pipe.
• Inspect the system for misalignment of components. This may lead to sagging and unwanted
stresses in the joints.
If any corrections are required they must be computed before installing the replacement water
heater.
Condensate Elbow Assembly
After connecting the exhaust vent pipe, the condensate trap assembly (supplied) must be
connected to the condensate drain nipple on the water heater.
Find the 90° Orienter from the accessory box and attach the union labeled ‘A’ to the
condensate drain nipple on the heater. Apply a bead of silicone around the outside of the
condensate drain nipple. For maximum durability and sealing, use a high heat silicone
caulk appropriate for direct vent appliances (rated for at least 150°F). Push the end of the
union onto the drain as far as the union allows.
D
DETAIL D
SCALE 1 : 12
RUNNING TRAP PORTION
ORIENTER
CONDENSATE DRAIN NIPPLE
Figure 7: Installation of the Condensate Trap

Page 19
SECTION IV: INSTALLATION
Determine which direction minimizes the length of the condensate drain line, and point
the orienter in that direction. Install the trap portion by connecting the union parts
labeled ‘B’ so that it is pointing in the proper direction. See Figure 7 for a view of how
the condensate trap is assembled, and Figure 8 for a view of both orientation options.
Figure 8: Orientation of the Condensate Trap

Page 20
SECTION IV: INSTALLATION
The orientation of the trap portion of the drain is critical for proper venting of gas and
drainage of condensate. This portion must be level after both unions are fully tightened. See
Figure 9 for proper final orientation of the assembly.
After the exhaust assembly and the condensate trap are properly connected, apply more
silicone caulk around the outside of each connection. Caulk all the way around the pipes.
If a proper seal is not made, combustion gas will leak into the room and condensate will
collect on the floor. See Figure 10 for location of seal.
E
DETAIL E
SCALE 1 : 8
TRAP MUST BE LEVEL
Figure 9: Levelness of Trap
G
DETAIL G
SCALE 1 : 16
4" X 6" INCREASER
(FACTORY SUPPLIED)
4" FLEXIBLE COUPLING
(FACTORY SUPPLIED"
AIR INTAKE
H
M
DETAIL H
SCALE 1 : 16
6" 22.5° ELBOW
(FACTORY SUPPLIED)
6" PVC STRAIGHT COUPLING
(FACTORY SUPPLIED)
6" STRAIGHT PIPE
(FACTORY SUPPLIED)
K
DETAIL K
SCALE 1 : 16
SEAL WITH
SILICONE CAULK
ALL THE WAY
AROUND
CONNECTION.
DETAIL M
SCALE 1 : 16
EXHAUST PIPE ELBOW
UNION 'B'
3/4" FEMALE NPT
EXHAUST VENT
Figure 10: Sealing the Connections
A detailed view of the condensate trap is shown in Figure 11. The discharge portion of the trap
is designed with a vent and threaded ¾” female NPT connection. The trap may be cleaned by
disconnecting union B and the threaded connection, then running water through the trap.
Use rigid PVC pipe for the condensate drain line. The line must slope down, 1/8” per foot,
away from the point of connection towards the drain. If there is insufficient clearance be-
tween the connection point and the floor to maintain slope, the heater should be installed on
a concrete slab or use a low-profile condensate pump.
Figure 11: Detailed View
G
DETAIL G
SCALE 1 : 16
4" X 6" INCREASER
(FACTORY SUPPLIED)
4" FLEXIBLE COUPLING
(FACTORY SUPPLIED"
AIR INTAKE
H
M
DETAIL H
SCALE 1 : 16
6" 22.5° ELBOW
(FACTORY SUPPLIED)
6" PVC STRAIGHT COUPLING
(FACTORY SUPPLIED)
6" STRAIGHT PIPE
(FACTORY SUPPLIED)
K
DETAIL K
SCALE 1 : 16
SEAL WITH
SILICONE CAULK
ALL THE WAY
AROUND
CONNECTION.
SEAL
CONNECTION
WITH PVC PRIMER
AND CEMENT.
DETAIL M
SCALE 1 : 16
EXHAUST PIPE ELBOW
UNION 'B'
3/4" FEMALE NPT
EXHAUST VENT