A.O. Smith ***81-140 Installation and user guide

1
COMMERCIAL GAS
Lined Tank Type Water Heater
•Installation •Service •Maintenance
PLACE THESE INSTRUCTIONS ADJACENT TO HEATER AND
NOTIFY OWNER TO KEEP FOR FUTURE REFERENCE.
PRINTED IN U.S.A. 1102 PART NO. 195091-000
CAUTION
TEXT PRINTED OR OUTLINED IN RED CONTAINS
INFORMATION RELATIVE TO YOUR SAFETY. PLEASE READ
THOROUGHLY BEFORE INSTALLING AND USING THIS
APPLIANCE.

2
The illustration shows a typical gas-fired commercial gas power burner, tank-type
water heater. The principal components of the heater are shown and identified
here. By referring to the plate on the heater jacket the unit may be identified in the
specifications presented in Table 1 and 2.
FEATURES AND SPECIFICATIONS
Model Designator: Sample ***81-140NEA N = Natural Gas
*** = Letter designator E = 3 Year Warranty
81 = Gallon Capacity A = ASME Construction
140 = 140,000 BTU/HR imput
TABLE 2 - MODEL ENERGY CONSUMPTION AND PERFORMANCE DATA
STORAGE MAXIMUM
MODELS CAPACITY IMPUT RATING RECOVERY RATE RECOVERY RATE AMPERES
U.S. GALLONS BTU/HR. GPH@100°F RISE GPH@140°F RISE 120V, 60Hz, 1Ø
***81-140 81 140,000 136 97 5
***81-199 81 199,000 193 138 5
***81-270 81 270,000 262 187 5
***81-370 81 370,000 359 256 5
TABLE 1 - NOMINAL MODEL DIMENSIONS AND WEIGHTS
MODELS A B C D E G H J GAS APPROX. SHIP. IN OUT
WT. (LBS.)
ASME STD.
***81-140 74 3/4 65 26 3/4 6 21 3/8 27 3/4 38 85 1/4 1/2 658 556 1 1/2 1 1/2
***81-199 74 3/4 65 26 3/4 6 21 3/8 27 3/4 38 85 1/4 1/2 635 545 1 1/2 1 1/2
***81-270 74 3/4 65 26 3/4 8 21 3/8 27 3/4 38 85 1/4 3/4 632 547 1 1/2 1 1/2
***81-370 74 3/4 65 26 3/4 8 21 3/8 27 3/4 38 85 1/4 3/4 731 634 1 1/2 1 1/2

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FOREWORD
These designs comply with the latest version of the American
National Standard for Gas Water Heaters, Volume III,
ANSI Z21.10.3 - CSA 4.3.
Detailed installation diagrams are found in this manual. These
diagrams will serve to provide the installer with a reference for
the materials and methods of piping necessary. It is highly
essential that all water, gas piping and wiring be installed as shown
on the diagrams.
Particular attention should be given to the installation of
thermometers at the locations indicated on the diagrams as these
are necessary for checking the proper functioning of the heater.
The ***81-140 through ***81-370 models are designed to
operate on either natural or propane gases. HOWEVER, MAKE
SURE the gas on which the heater will operate is the same as
that specified on the heater model and rating plate.
THESE HEATERS MUST NOT BE INSTALLED DIRECTLY ON
COMBUSTIBLE FLOORS.
In addition to these instructions, the equipment shall be installed
in accordance with those installation regulations in force in the
local area where the installation is to be made. These shall be
carefully followed in all cases. Authorities having jurisdiction
should be consulted before installations are made.
The installation must conform to these instructions and the local
code authority having jurisdiction. In the absence of local codes
the installation must comply with the latest editions of the National
Fuel Gas Code, ANSI Z223.1/NFPA 54 and the National Electric
Code, NFPA 70. The former is available from the Canadian
Standards Association, 8501 Pleasant Valley Road, Cleveland,
OH 44131 and both documents are available from the National
Fire Protection Association, 1 Batterymarch Park, Quincy,
MA 02269.
TABLE OF CONTENTS
PAGE
FEATURES AND SPECIFICATIONS ........................................... 2
FOREWORD ............................................................................... 3
GENERAL SAFETY INFORMATION
Precautions ............................................................................. 3
Chemical Vapor Corrosion ...................................................... 3-4
Improper Combustion ............................................................. 4
Liquid Petroleum Models ......................................................... 4
Extended Non-Use Periods ..................................................... 4
Insulation Blankets .................................................................. 4
High Altitude Installation ......................................................... 4-5
FEATURES
High Limit Switch (E.C.O.) ...................................................... 5
Circulating Pump ..................................................................... 5
Dishwashing Machine Requirements ...................................... 5
INSTALLATION INSTRUCTIONS
Required Ability ....................................................................... 5
Uncrating ................................................................................. 5
Locating the Heater ................................................................. 5-6
Clearances .............................................................................. 6
Levelling .................................................................................. 6
Hard Water .............................................................................. 6
Air Requirements .................................................................... 6-7
Mechanical Exhausting of Room Air ....................................... 7
Venting .................................................................................... 7
Barometric Draft Control Assembly ........................................ 7
Vent Connection ...................................................................... 7-8
Drain Valve and Access Panels .............................................. 8
Burner Installation ................................................................... 8
Gas Meter Size-City Gases Only ............................................ 8
Gas Pressure Regulation ........................................................ 8-9
Gas Piping ............................................................................... 9
Heater Wiring Instructions ...................................................... 9-10
Water Line Connection .......................................................... 10
Water (Potable) Heating and Spacing.................................. 10
Relief Valve ............................................................................ 10
Thermometers (Not Supplied) ............................................... 10
Wiring for ***81-140 thru ***81-370 ....................................... 11
INSTALLATION DIAGRAMS ...................................................... 12-15
Manifold Kits .......................................................................... 16
PRIOR TO START UP
Required Equipment And Ability .......................................... 17
Purging ................................................................................... 17
Water Temperature Control ................................................... 17
Operation & Adjustment Procedure ...................................... 18
Adjustment Procedure ........................................................... 19-20
MAINTENANCE
Maintenance Schedule ......................................................... 20
Flushing .................................................................................. 20
Draining .................................................................................. 20
Sediment Removal ................................................................ 20
Lime Scale Removal ............................................................. 20-21
Relief Valve ........................................................................... 21
Circulating Pump ................................................................... 21
Power Burner .......................................................................... 21
Vent System ............................................................................ 21
Barometric Draft Control ........................................................ 21-22
Electrical Servicing ................................................................ 22
CHECKLIST AND SERVICE INFORMATION ............................ 22-23
TROUBLESHOOTING ................................................................ 23
Replacement Parts ................................................................. 23
PARTS LIST ................................................................................ 24-27
PAGE
GENERAL SAFETY INFORMATION
PRECAUTIONS
DO NOT USE THIS APPLIANCE IF ANY PART HAS BEEN
UNDERWATER. 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.
IF THE UNIT IS EXPOSED TO THE FOLLOWING, DO NOT
OPERATE HEATER UNTIL ALL CORRECTIVE STEPS HAVE
BEEN MADE BY A QUALIFIED SERVICEMAN.
1. EXTERNAL FIRE.
2. DAMAGE.
3. FIRING WITHOUT WATER.
4 SOOTING.
Heater must be protected from freezing downdrafts during
shutdown periods.
CHEMICAL VAPOR CORROSION
WARNING
CORROSION OF THE FLUEWAYS AND VENT SYSTEM MAY
OCCUR IF AIR FOR COMBUSTION CONTAINS CERTAIN
CHEMICAL VAPORS WHICH BREAK DOWN INTO ACIDS AT
HIGH TEMPERATURE. SUCH CORROSION MAY RESULT IN
FAILURE AND RISK OF ASPHYXIATION.

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Spray can propellants, cleaning solvents, refrigerator and air
conditioning refrigerants, swimming pool chemicals, calcium
and sodium chloride (water softener salt), waxes, and process
chemicals contain typical compounds which are potentially
corrosive. Do not store products of this sort near the heater.
Also, air which is brought in contact with the heater should not
contain any of these chemicals. If necessary, uncontaminated
air should be obtained from remote or outside sources. The
limited warranty is voided when failure of water heater is due to
a corrosive atmosphere. (Refer to the limited warranty for
complete terms and conditions).
IMPROPER COMBUSTION
WARNING
ATTIC AND/OR EXHAUST FANS OPERATING ON THE PREMISES
WITH A WATER HEATER CAN RESULT IN CARBON MONOXIDE
POISONING AND DEATH.
OPERATING THESE FANS CAN PRODUCE A NEGATIVE DRAFT
IN THE AREA OF THE WATER HEATER PREVENTING THE
PRODUCTS OF COMBUSTION FROM EXHAUSTING THROUGH
THE CHIMNEY OR VENT PIPE.
The venting of the water heater should be inspected by a qualified
service technician at the time of installation and periodically
thereafter to ensure a down-draft condition does not exist.
DO NOT OBSTRUCT THE FLOW OF COMBUSTION AND
VENTILATING AIR. ADEQUATE AIR FOR COMBUSTION AND
VENTILATION MUST BE PROVIDED FOR SAFE OPERATION.
LIQUID PETROLEUM MODELS
Water heaters for propane or liquefied petroleum gas (LPG) are
different from natural gas models. A natural gas heater will not
function safely on LP gas and no attempt should be made to
convert a heater from natural gas to LP gas.
LP gas must be used with great caution. It is highly explosive
and heavier than air. It collects first in the low areas making its
odor difficult to detect at nose level. If LP gas is present or even
suspected, do not attempt to find the cause yourself. Go to a
neighbor’s house, leaving your doors open to ventilate the house,
then call your gas supplier or service agent. Keep area clear
until a service call has been made.
At times you may not be able to smell an LP gas leak. One
cause is odor fade, which is a loss of the chemical odorant that
gives LP gas its distinctive smell. Another cause can be your
physical condition, such as having a cold or diminishing sense
of smell with age. For these reasons, the use of a propane gas
detector is recommended.
Only trained LP professionals should conduct the required safety
checks in accordance with industry standards.
EXTENDED NON-USE PERIODS
WARNING
HYDROGEN GAS CAN BE PRODUCED IN A HOT WATER
SYSTEM SERVED BY THIS HEATER THAT HAS NOT BEEN USED
FOR A LONG PERIOD OF TIME (GENERALLY TWO WEEKS OR
MORE). HYDROGEN GAS IS EXTREMELY FLAMMABLE. To
reduce the risk of injury under these conditions, it is
recommended that the hot water faucet be opened for several
minutes at the kitchen sink before using any electrical appliance
connected to the hot water system. If 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.
INSULATION BLANKETS
Insulation blankets available to the general public for external
use on gas water heaters are not approved for use on your water
heater. The purpose of an insulation blanket is to reduce the
standby heat loss encountered with storage tank water heaters.
Your water heater meets or exceeds the ASHRAE/IES
90.1b-1992 standards with respect to insulation and standby
loss requirements making an insulation blanket unnecessary.
WARNING
Should you choose to apply an insulation blanket to this heater,
you should follow these instructions. Failure to follow these
instructions can result in fire, asphyxiation, serious personal injury
or death.
•Do not apply insulation to the top of the water heater, as this
will interfere with safe operation of drafthood.
•Do not cover the temperature & pressure relief valve.
•Do not cover the instruction manual. Keep it on the side of the
water heater or nearby for future reference.
•Do obtain new labels from manufacturer for placement on
the blanket directly over the existing labels.
HIGH ALTITUDE INSTALLATIONS
WARNING
INSTALLATIONS ABOVE 2000 FEET REQUIRE REPLACEMENT
OF THE BURNER ORIFICE IN ACCORDANCE WITH SECTION
8.1.2 OF THE NATIONAL FUEL GAS CODE (ANSI Z223.1).
FAILURE TO REPLACE THE ORIFICE WILL RESULT IN
IMPROPER AND INEFFICIENT OPERATION OF THE APPLIANCE
RESULTING IN THE PRODUCTION OF INCREASED LEVELS
OF CARBON MONOXIDE GAS IN EXCESS OF SAFE LIMITS
WHICH COULD RESULT IN SERIOUS PERSONAL INJURY OR
DEATH.
As elevation above sea level is increased, there is less oxygen
per cubic foot of air. Therefore, the heater input rate should be
reduced at high altitudes for satisfactory operation with the
reduced oxygen supply. Failure to make this reduction would
result in an overfiring of the heater, causing sooting, poor
combustion and/or unsatisfactory heater performance.
Ratings specified by manufacturers for most appliances apply
for elevations up to 2000 feet. For elevations above 2000 feet,
ratings must be reduced at the rate of 4% for each 1000 feet
above sea level. For example, if a heater is rated at 120,000 Btu/
hr. at sea level, to rate the heater at 4000 feet, you subtract 4
(once for each thousand feet) x .04 (4% input reduction) x 120,000
(the original rating) from the original rating. Therefore, to calculate
the input rating at 4000 feet: 4 x .04 x 120,000 = 19,200 btu/hr.,
120,000 - 19,200 = 100,800 btu/hr. At 6000 feet elevation, the
heater rating would be 91,200 btu/hr.

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The input reduction is primarily achieved by reducing the size of
the main burner orifices. To do this, the main burner orifices
require replacement with orifices sized for the particular installation
elevation. Correct orifice sizing and parts may be obtained from
the manufacturer. See the REPLACEMENT PARTS section of
this manual. When ordering, be sure to state the model number
and the altitude of the location where the heater is being
installed.
Upon completion of derating of the heater, adjustment to the gas
pressure regulator may be required. See ADJUSTMENT
PROCEDURE in this manual for inlet and manifold pressure
requirements.
Also, due to the input rating reduction required at high altitudes,
the output rating of the appliance is also reduced and should be
compensated for in the sizing of the equipment for applications.
FEATURES
HIGH LIMIT SWITCH (E.C.O.)
The dual bulb controller ((fig. 1) contains the high limit (energy
cutoff) sensor. The high limit switch interrupts main burner gas
flow should the water temperature reach 205°F (96°C).
In the event of high limit switch operation, the appliance cannot
be restarted unless the water temperature is reduced by at least
20°F (11°C) and the high limit reset button on front of limit control
(fig.1) is depressed.
DUAL-BULB THERMOSTAT (COVER REMOVED)
FIGURE 1
Continued manual resetting of high limit control, preceded by
higher than usual water temperature is evidence of high limit switch
operation. The following is a possible reason for high limit switch
operation.
• A malfunction in the thermostatic controls would allow the gas
valve to remain open causing water temperature to exceed
the thermostat setting. The water temperature would continue
to rise until high limit switch operation.
Contact your dealer or servicer if continued high limit switch
operation occurs, to determine the reason for operation.
CIRCULATING PUMP
A circulating pump is used when a system requires a circulating
loop or there is a storage tank used in conjunction with the heater.
Refer to the piping diagrams at rear of manual for electrical
hookup information and install in accordance with the latest
version of the National Electric Code ANSI/NFPA No. 70.
Only all bronze circulators are used with commercial water heaters.
Although circulators are oiled and operated by the manufacturer
some circulators must be oiled again before operating. Please
refer to manufacturer’s instructions.
DISHWASHING MACHINE REQUIREMENT
All dishwashing machines meeting the National Sanitation
Foundation requirements are designed to operate with water flow
pressures between 15 and 25 pounds per square inch. Flow
pressures above 25 pounds per square inch, or below 15 pounds
per square inch, will result in improperly sanitized dishes. Where
pressures are high, a water pressure reducing or flow regulating
control valve should be used in 1800line to the dishwashing
machine, and should be adjusted to deliver water between these
limits.
The National Sanitation Foundation also recommends circulation
of 1800F water. Where this is done, the circulation should be
very gentle so that it does not cause any unnecessary turbulence
inside the water heater. The circulation should be just enough to
provide 1800F water at the point of take-off to the dishwashing
machine. Adjust flow by means of the plug cock in the circulating
line.
INSTALLATION INSTRUCTIONS
REQUIRED ABILITY
INSTALLATION OR SERVICE OF THIS WATER HEATER
REQUIRES ABILITY EQUIVALENT TO THAT OF A LICENSED
TRADESMAN IN THE FIELD INVOLVED. PLUMBING, AIR
SUPPLY, VENTING, GAS SUPPLY AND ELECTRICAL WORK
ARE REQUIRED.
UNCRATING
Uncrate the heater by removing the outside mat and top locator.
The shipping pallet must be removed from the unit. It may be
possible to simply unbolt the base from the pallet and, with the
help of 2 or more persons, work the unit off the pallet. Some
units will be too heavy and will require the use of jacks or lifting
equipment to safely remove the pallet and move the unit into
position. Be careful when moving this heater. It will tip over
easily.
The heater is shipped with a burner and draft control. The burner
and draft control are shipped in separate cartons. They should
be installed as received without any alterations.
Discard the shipping crate and packaging cartons in an appropriate
manner.
LOCATING THE HEATER
WARNING
THERE IS A RISK IN USING FUEL BURNING APPLIANCES
SUCH AS GAS WATER HEATERS IN ROOMS, GARAGES OR
OTHER AREAS WHERE GASOLINE, OTHER FLAMMABLE
LIQUIDS OR ENGINE DRIVEN EQUIPMENT OR VEHICLES ARE
STORED, OPERATED OR REPAIRED. FLAMMABLE VAPORS

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ARE HEAVY AND TRAVEL ALONG THE FLOOR AND MAY BE
IGNITED BY THE HEATER’S IGNITION SYSTEM OR MAIN
BURNER FLAMES CAUSING FIRE OR EXPLOSION. SOME
LOCAL CODES PERMIT OPERATION OF GAS APPLIANCES
IN SUCH AREAS IF THEY ARE INSTALLED 18 INCHES OR
MORE ABOVE THE FLOOR. THIS MAY REDUCE THE RISK IF
LOCATION IN SUCH AN AREA CANNOT BE AVOIDED.
WARNING
FLAMMABLE ITEMS, PRESSURIZED CONTAINERS OR ANY
OTHER POTENTIAL FIRE HAZARDOUS ARTICLES MUST
NEVER BE PLACED ON OR ADJACENT TO THE HEATER.
OPEN CONTAINERS OF FLAMMABLE MATERIAL SHOULD
NOT BE STORED OR USED IN THE SAME ROOM WITH THE
HEATER.
THE HEATER SHALL BE LOCATED OR PROTECTED SO IT IS
NOT SUBJECT TO PHYSICAL DAMAGE BY A MOVING
VEHICLE.
THE HEATER MUST NOT BE LOCATED IN AN AREA WHERE
IT WILL BE SUBJECT TO FREEZING.
When installing the heater, consideration must be given to proper
location. Location selected should be as close to a gas vent or
chimney as practicable, with adequate air supply and as
centralized with the piping system as possible.
LOCATE HEATER NEAR A FLOOR DRAIN. THE HEATER
SHOULD BE LOCATED IN AN AREA WHERE LEAKAGE FROM
THE TANK OR CONNECTIONS WILL NOT RESULT IN DAMAGE
TO THE ADJACENT AREA OR TO LOWER FLOORS OF THE
STRUCTURE.
WHEN SUCH LOCATIONS CANNOT BE AVOIDED, A SUITABLE
METAL DRAIN PAN, ADEQUATELY DRAINED, SHOULD BE
INSTALLED UNDER THE HEATER. Such pans should be
fabricated with sides at least 2" deep, with length and width at
least 2" greater than the diameter of the heater and must be piped
to an adequate drain. THE PAN MUST NOT RESTRICT
COMBUSTION AIR FLOW.
Units which are to be installed on combustible flooring must be
supported by a full layer of hollow concrete blocks, from 8" to 12"
thick and extending 12" (minimum) beyond the heater in all
directions. The concrete blocks must provide an unbroken
concrete surface under the heater with the hollows running
continuously and horizontally. A 3/16 inch steel plate must cover
the concrete blocks, see fig. 2.
NOTE: If electrical conduits run under the floor of the proposed
heater location, insulate the floor asrecommended
above.
PROPER INSTALLATION ON COMBUSTIBLE FLOORING
FIGURE 2
For appliance installation locations with elevations above 2000
feet, refer to HIGH ALTITUDE INSTALLATIONS section of this
manual for input reduction procedure.
CLEARANCES
These heaters are design certified by the Underwriter’s
Laboratories for installation on non-combustible flooring in an
alcove with clearances to combustible construction of 6" from
the sides and rear, and 6" minimum between vent pipe and ceiling.
Minimum clearance from barometric draft control to combustible
material is 6". A minimum of 21" from top of heater to the ceiling
is required, except for the ***81-370 which requires a minimum
of 24".
A clearance of 24" shall be maintained from serviceable parts,
such as the relief valve, power burner, thermostat and drain valve.
PROPER INSTALLATION CLEARANCES
FIGURE 3
LEVELLING
The heater shall be installed plumb to the ground. If it is necessary
to adjust the heater, use metal shims under the channel type skid
base.
HARD WATER
Where hard water conditions exist, water softening or the threshold
type of water treatment is recommended. This will protect the
dishwashers, coffee urns, water heaters, water piping and other
equipment.
See MAINTENANCE section for details of tank cleanout
procedures.
AIR REQUIREMENTS
KEEP APPLIANCE AREA FREE FROM COMBUSTIBLE
MATERIALS, GASOLINE AND OTHER FLAMMABLE VAPORS
AND LIQUIDS.
DO NOT OBSTRUCT THE FLOW OF COMBUSTION OR
VENTILATING AIR.
WARNING
FOR SAFE OPERATION PROVIDE ADEQUATE AIR FOR
COMBUSTION AND VENTILATION. AN INSUFFICIENT SUPPLY
OF AIR WILL CAUSE RECIRCULATION OF COMBUSTION
PRODUCTS RESULTING IN AIR CONTAMINATION THAT MAY
BE HAZARDOUS TO LIFE. SUCH A CONDITION OFTEN WILL
RESULT IN A YELLOW, LUMINOUS BURNER FLAME, CAUSING

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CARBONING OR SOOTING OF THE COMBUSTION CHAMBER,
BURNERS AND FLUE TUBES AND CREATES A RISK OF
ASPHYXIATION.
MECHANICAL EXHAUSTING OF ROOM AIR
Where an exhaust fan is installed in the same room with a heater,
sufficient openings for air must be provided in the walls.
UNDERSIZED OPENINGS WILL CAUSE AIR TO BE DRAWN
INTO THE ROOM THROUGH THE CHIMNEY, CAUSING POOR
COMBUSTION. SOOTING MAY RESULT IN SERIOUS DAMAGE
TO THE HEATER AND RISK OF FIRE OR EXPLOSION.
UNCONFINED SPACE
In buildings of conventional frame, brick or stone construction,
unconfined spaces may provide adequate air for combustion,
ventilation, and draft hood dilution.
If the unconfined space is within a building of tight construction
(buildings using the following construction: weather stripping,
heavy insulation, caulking, vapor barrier, etc.), air for combustion,
ventilation and draft hood dilution must be obtained from outdoors.
The installation instructions for confined spaces in tightly
constructed buildings must be followed to ensure adequate air
supply.
CONFINED SPACE
When drawing combustion and dilution air from inside a
conventionally constructed building to a confined space, such a
space shall be provided with two permanent openings, ONE IN
OR WITHIN 12 INCHES OF THE ENCLOSURE TOP AND ONE
IN OR WITHIN 12 INCHES OF THE ENCLOSURE BOTTOM.
Each opening shall have a free area of at least one square inch
per 1000 Btuh of the total input of all appliances in the enclosure,
but not less than 100 square inches.
If the confined space is within a building of tight construction, air
for combustion, ventilation and draft hood dilution must be
obtained from outdoors. When directly communicating with the
outdoors through vertical ducts, two permanent openings, located
in the above manner, shall be provided. Each opening shall have
a free area of not less than one square inch per 4000 Btuh of the
total input of all appliances in the enclosure. If horizontal ducts
are used, each opening shall have a free area of not less than
one square inch per 2000 Btuh of the total input of all appliances
in the enclosure.
VENTING
WARNING
THE INSTRUCTIONS IN THIS SECTION ON VENTING MUST
BE FOLLOWED TO AVOID CHOKED COMBUSTION OR
RECIRCULATION OF FLUE GASES. SUCH CONDITIONS
CAUSE SOOTING OR RISKS OF FIRE AND ASPHYXIATION.
Type B venting may be used with these heaters. All local and
utility regulations on venting should be followed.
BAROMETRIC DRAFT CONTROL ASSEMBLY
A double-acting barometric draft control assembly is provided with
each unit. The draft control assembly must be installed without
alteration. This assembly is factory adjusted for horizontal
application only and must be attached to the heater as shown in
figure 4. The outlet of the draft control assembly may be rotated
to face in direction needed. The assembly must be fitted to the
jacket cover such that it is plumb and level to the ground. Fasten
the draft control assembly to the top cover using sheet metal
screws at three locations, or more, as required.
Dampers or other obstructions must not be installed between the
heater and the barometric draft control assembly.
Do not adjust settings on gate. Counterweight washers are factory
adjusted and should result in breeching pressure measurements
at the combustion test hole (fig. 4) within the range shown in
table 6.
NOTE: A negative draft must be maintained in the vent piping.
When installed, the damper gate must pivot freely in the ring
guides. This gate will automatically adjust to regulate the chimney
draft imposed on the heater.
PROPER DRAFT CONTROLLER AND
VENT PIPE INSTALLATION
FIGURE 4
VENT CONNECTION
Vent connections must be made to an adequate stack or chimney.
Refer to the National Fuel Gas Code (latest version) or to the
vent pipe manufacturer’s gas vent and chimney sizing table to
properly design and size the venting system. Refer to Table 3 for
the vent pipe size required for installation to the barometric draft
control assembly outlet.
TABLE 3 - BAROMETRIC DRAFT CONTROL
ASSEMBLY OUTLET SIZE
DRAFT CONTROL
MODEL OUTLET DIAMETER
***81-140 6”
***81-199 6”
***81-270 8”
***81-370 8”
Where an existing chimney or vent is to be used, be sure that the
chimney or vent has adequate capacity for the number and sizes
of gas appliances being vented through it. Inspect the chimney
or vent and remove all soot or other obstructions which will retard
free draft.
Vent connectors making horizontal runs must have a minimum
upward slope toward the chimney or vent of 1/4 inch per foot.
Vent connector length should be kept as short as possible. Be
sure that the vent pipe does not extend beyond the inside wall of
a chimney.

8
In venting systems where a continuous or intermittent back
(positive) draft is found to exist, the cause must be determined
and corrected. In some cases, a special vent cap may be
required.
Do not install this unit on the positive draft side of a venting system
being served by a power exhauster.
DRAIN VALVE AND ACCESS PANELS
The heaters are equipped with a 3/4" drain valve mounted above
and to the left of the burner. See page 2.
The combustion chamber observation access panel is located
above and to the left of the burner. A plug located under the
panel, see fig. 5, is inserted into the combustion chamber wall.
This plug should not be removed except, in rare cases, when the
combustion chamber requires cleaning or replacement.
WARNING
DO NOT REMOVE THIS PLUG WHILE THE HEATER IS IN
OPERATION. THE COMBUSTION CHAMBER IS UNDER
PRESSURE AND MAIN BURNER FLAMES WILL ESCAPE
THROUGH THE OPENING. THIS IS AN EXTREMELY
HAZARDOUS CONDITION WHICH MAY RESULT IN SERIOUS
INJURY.
COMBUSTION CHAMBER ACCESS PORT
FIGURE 5
IMPORTANT
Before removing the access panel and observation plug, BE SURE
THAT THE ELECTRICAL POWER TO THE HEATER IS “OFF”.
This will prevent the heater from operating while servicing the
unit. Remember to install the plug and access cover BEFORE
restoring electrical power to the heater.
Another access panel is located above and to the right of the
burner, fig. 6. This panel covers the cleanout opening in the tank
which is sealed by a gasket and cover.
TANK CLEANOUT PORT
FIGURE 6
Occasionally, some water seepage will occur at a cleanout port.
To correct this situation, slightly tighten the cleanout cover bolts
until the seepage is eliminated. Do not overly tighten the bolts or
the cleanout gasket will be damaged. Tighten each bolt gradually
and alternate between opposed bolts on the cleanout cover.
BURNER INSTALLATION
Remove the factory-installed insulation covering the combustion
chamber opening. (A utility knife is useful for cutting out the
insulation). Cut the insulation back even with the jacket opening.
Install the flange gasket (which is usually taped to the heater
jacket) over the three bolts protruding from the tank at the
combustion chamber opening.
Remove the hardware (3 hex nuts, 3 flat washers, and 3 lock
washers) from the shipping bag attached to the heater’s electrical
conduit.
POWER BURNER INSTALLATION
FIGURE 7
Begin assembling the power burner to the tank by placing the
power burner nozzle in the combustion chamber opening. Slide
the nozzle into the tank and rotate the mounting flange to engage
the mounting bolts, refer to Figure 7. Then, place the flat washers
followed by the lock washers, and finally the hex nuts on the
mounting bolts. Hand tighten the nuts. Then gradually tighten
each nut alternating between the 3 mounting bolts. Do not over
tighten as damage to the flange gasket or to the tank may result.
Refer to figure 7.
GAS METER SIZE — CITY GASES ONLY
Be sure that the gas meter has sufficient capacity to supply the
full-rated gas input of the water heater as well as the
requirements of all other gas fired equipment supplied by the
meter. If gas meter is too small, request the gas company to
install a larger meter having adequate capacity.
GAS PRESSURE REGULATION
Main manual pressure to the water heater should be between
4.5" minimum and 10.5" maximum w.c. for natural gas and 11.0"
minimum and 13.0" maximum w.c. for propane gas. The inlet
gas pressure must not exceed the maximum value. A service
regulator is necessary if higher gas pressures are encountered.
See Table 6.

9
WARNING
THE HEATER IS NOT INTENDED FOR OPERATION AT HIGHER
THAN 10.5" W.C. - NATURAL GAS, 13.0" W.C. - PROPANE GAS
(1/2 POUND PER SQUARE INCH GAUGE) SUPPLY GAS
PRESSURE. HIGHER GAS PRESSURES REQUIRE
SUPPLEMENTAL REDUCING SERVICE REGULATION.
EXPOSURE TO HIGHER GAS SUPPLY PRESSURE MAY CAUSE
DAMAGE TO THE GAS CONTROLS WHICH COULD RESULT IN
FIRE OR EXPLOSION. IF OVERPRESSURE HAS OCCURRED,
SUCH AS THROUGH IMPROPER TESTING OF GAS LINES OR
EMERGENCY MALFUNCTION OF THE SUPPLY SYSTEM, THE
GAS VALVE MUST BE CHECKED FOR SAFE OPERATION. MAKE
SURE THAT THE OUTSIDE VENTS ON THE SUPPLY
REGULATORS AND THE SAFETY VENT VALVES ARE
PROTECTED AGAINST BLOCKAGE. THESE ARE PARTS OF
THE GAS SUPPLY SYSTEM, NOT THE HEATER. VENT
BLOCKAGE MAY OCCUR DURING ICE STORMS.
DISCONNECT THE APPLIANCE AND ITS MAIN MANUAL GAS
SHUTOFF VALVE FROM THE GAS SUPPLY PIPING SYSTEM
DURING ANY SUPPLY PRESSURE TESTING EXCEEDING 1/2
PSIG. GAS SUPPLY LINE MUST BE CAPPED WHEN
DISCONNECTED FROM THE HEATER. FOR TEST
PRESSURES OF 1/2 PSIG OR LESS, THE APPLIANCE NEED
NOT BE DISCONNECTED, BUT MUST BE ISOLATED FROM
THE SUPPLY PRESSURE TESTING BY CLOSING THE MAIN
MANUAL GAS SHUT OFF VALVE.
GAS PIPING
Contact your local gas service company to ensure that adequate
gas service is available and to review applicable installation
codes for your area.
Size the main gas line in accordance with Table 4. The figures
shown are for iron pipe or equivalent at 0.5 in. w.c. pressure
drop, which is considered normal for low pressure systems.
Note that an excess number of fittings such as elbows and tees
will add to the pipe pressure drop. No additional allowance is
necessary for an ordinary number of fittings.
IF COPPER SUPPLY LINES ARE USED THEY MUST BE
INTERNALLY TINNED AND CERTIFIED FOR GAS SERVICE.
IT IS IMPORTANT TO GUARD AGAINST GAS VALVE FOULING
FROM CONTAMINANTS IN THE GAS WAYS. SUCH FOULING
MAY CAUSE IMPROPER OPERATION, FIRE OR EXPLOSION.
BEFORE ATTACHING THE GAS LINE, BE SURE THAT ALL GAS
PIPE IS CLEAN ON THE INSIDE.
TO TRAP ANY DIRT OR FOREIGN MATERIAL IN THE GAS
SUPPLY LINE, A DRIP LEG (SOMETIMES CALLED DIRT LEG)
MUST BE INCORPORATED IN THE PIPING. SEE FIG. 8. THE
DRIP LEG MUST BE READILY ACCESSIBLE, REFER TO FIG. 8,
AND NOT SUBJECT TO FREEZING CONDITIONS. INSTALL IN
ACCORDANCE WITH RECOMMENDATIONS OF SERVICING
GAS SUPPLIERS. REFER TO THE NATIONAL FUEL GAS CODE
(LATEST VERSION).
To prevent damage, care must be taken not to apply too much
torque when attaching gas supply pipe to gas valve inlet.
TABLE 4
MAXIMUM CAPACITY OF PIPE IN CUBIC FEET
OF GAS PER HOUR
(Based upon a Pressure Drop of 0.5 inch Water Column and
0.6 Specific Gravity Gas and max. gas pressure of .5 psig)
LENGTH NOMINAL IRON PIPE SIZE (INCHES)
IN FEET 1/2 3/4 1 1 1/4 1 1/2 2 2 1/2 3 4
10 175 360 680 1,400 2,100 3,950 6,300 11,000 23,000
20 120 250 465 950 1,460 2,750 4,350 7,700 15,800
30 97 200 375 770 1,180 2,200 3,520 6,250 12,800
40 82 170 320 660 990 1,900 3,000 5,300 10,900
50 73 151 285 580 900 1,680 2,650 4,750 9,700
60 66 138 260 530 810 1,520 2,400 4,300 8,800
70 61 125 240 490 750 1,400 2,250 3,900 8,100
80 57 118 220 460 690 1,300 2,050 3,700 7,500
90 53 110 205 430 650 1,220 1,950 3,450 7,200
100 50 103 195 400 620 1,150 1,850 3,250 6,700
125 44 93 175 360 550 1,020 1,650 2,950 6,000
150 40 84 160 325 500 950 1,500 2,650 5,500
175 37 77 145 300 460 850 1,370 2,450 5,000
200 35 72 135 280 430 800 1,280 2,280 4,600
Apply joint compounds (pipe dope) sparingly and only to the male
threads of pipe joints. Do not apply compound to the first two
threads. Use joint compounds resistant to the action of liquefied
petroleum gases.
BEFORE PLACING THE HEATER IN OPERATION, CHECK FOR
GAS LEAKAGE. USE SOAP AND WATER SOLUTION, OR
OTHER MATERIAL ACCEPTABLE FOR THE PURPOSE IN
LOCATING GAS LEAKS. DO NOT USE MATCHES, CANDLES,
FLAME OR OTHER SOURCES OF IGNITION FOR THIS
PURPOSE.
POWER BURNER ASSEMBLY, GAS MANIFOLD AND SUGGESTED
INLET PIPING - FIGURE 8
HEATER WIRING INSTRUCTIONS
The power burner should be wired to the heater as shown in
Figure 9. The model’s rating plate (or see Table 2) provides the
electrical information needed to size the complete heater branch
supply circuit.
All electrical work must be installed in accordance with the latest
version of the National Electrical Code and local requirements.
When installed, the appliance must be electrically grounded in
accordance with local codes or, in the absence of local codes,
with the latest version of the National Electrical Code,
ANSI/NFPA 70.

10
With the power burner installed in the heater, the electrical wiring
can be completed. On ***81-140 and ***81-199 models, remove
the power burner backplate and fasten the conduit assembly to
the power burner assembly. Next, connect the black wire to the
terminal marked “1” and the white wire to the terminal
marked “2”.
On ***81-270 and ***81-370 models, remove the two screws
above and below the control board on the junction box cover of
the power burner. Swing the junction box cover open and fasten
the conduit assembly in one of the knock-out holes in the side of
the junction box. Connect the black wire to the terminal marked
“1” and the white wire to the terminal marked “2”.
Finally, bring electrical power to the junction box mounted on the
heater jacket. Fasten conduit to any convenient knock-out hole
in the junction box. Use the two wire nuts from the shipping bag
to connect the hot and neutral conductors to the black and white
wires, respectively. Connect the ground conductor to the ground
screw in the back of the junction box.
Check all electrical connections to be sure that they are proper
and secure.
DO NOT ENERGIZE THE BRANCH CIRCUIT BEFORE THE
HEATER TANK IS FILLED WITH WATER.
WATER LINE CONNECTION
This manual provides detailed installation diagrams (see pages
12-16) of this manual for typical methods of application for the
water heaters.
The water heater may be installed itself, or with a separate storage
tank, on both single and two-temperature systems. When used
with a separate storage tank, the circulation may be either by
gravity or by means of a circulating pump. When a circulating
pump is used it is important to note that the flow rate should be
slow so that there will be a minimum of turbulence inside the
heater.
If a water heater is installed in a closed water system, contact the
water supplier or local plumbing inspector on how to control this
situation.
WATER (POTABLE) HEATING AND SPACE
HEATING (See pages 12-16)
1. All piping components connected to this unit for space heating
applications shall be suitable for use with potable water.
2. Toxic chemicals, such as those used for boiler treatment, shall
NEVER be introduced into this system.
3. This unit may NEVER be connected to any existing heating
system or component(s) previously used with a non-potable
water heating appliance.
4. When the system requires water for space heating at
temperatures higher than required for domestic water
purposes, a tempering valve must be installed. Please refer
to installation diagrams on pages 12-16 of this manual for
suggested piping arrangements.
CAUTION
A closed system will exist if a check valve (without bypass),
pressure reducing valve (without bypass), or a water meter
(without bypass) is installed in the cold water line between the
water heater and street main (well).
Excessive pressure may develope in such closed systems,
causing premature tank failure or intermittent relief valve operation.
This is not a warranty failure. An expansion tank or similar device
may be required in the inlet supply line between the appliance
and the meter or valve to compensate for the thermal expansion
of the water.
SYSTEM CONNECTIONS
The system installation must conform to these instructions and
to the local code authority having jurisdiction. Good practice
requires that all heavy piping be supported.
RELIEF VALVE
This heater is equipped with an approved temperature and
pressure relief valve. ASME ratings cover pressure relief. A.G.A.
ratings cover release rate with temperature actuation.
Your local code authority may have other specific relief valve
requirements.
WARNING
THE PURPOSE OF RELIEF VALVE IS TO AVOID EXCESSIVE
PRESSURE OF TEMPERATURE INTO THE STEAM RANGE,
WHICH MAY CAUSE SCALDING AT FIXTURES, TANK
EXPLOSION, SYSTEM OR HEATER DAMAGE. NO VALVE IS
TO BE PLACED BETWEEN THE RELIEF VALVE AND THE
TANK.
A DRAIN LINE MUST BE CONNECTED TO THE RELIEF VALVE
TO DIRECT DISCHARGE TO A SAFE LOCATION TO AVOID
SCALDING OR WATER DAMAGE. THIS LINE MUST NOT BE
REDUCED FROM THE SIZE OF THE VALVE OUTLET AND
MUST NOT CONTAIN VALVES, RESTRICTIONS NOR SHOULD
IT BE LOCATED IN FREEZING AREAS. DO NOT THREAD OR
CAP THE END OF THIS LINE. RESTRICTED OR BLOCKED
DISCHARGE WILL DEFEAT THE PURPOSE OF THE VALVE
AND IS UNSAFE. INSTALL DISCHARGE LINE TO ALLOW
COMPLETE DRAINAGE OF BOTH THE VALVE AND LINE.
THERMOMETERS (Not Supplied)
Thermometers should be obtained and field installed as shown
in the installation diagrams.
Thermometers are installed in the system as a means of detecting
the temperature of the outlet water supply.

11
WIRING FOR ***81-140 THRU ***81-370
FIGURE 9
SCHEMATIC DIAGRAM
WIRING DIAGRAM

12
INSTALLATION DIAGRAMS
ONE TEMPERATURE - ONE HEATER VERTICAL STORAGE TANK FORCED CIRCULATION
WITH OR WITHOUT BUILDING RECIRCULATION
ONE TEMPERATURE - ONE HEATER HORIZONTAL STORAGE TANK
FORCED CIRCULATION WITH OR WITHOUT BUILDING RECIRCULATION
SCALD PREVENTION
HOT WATER CAN SCALD IF USED
CARELESSLY OR IN UNANTICIPATED
MANNER.
DANGER
TEMPERATURE SETTING SHOULD NOT EXCEED SAFE USE
TEMPERATURE AT FIXTURES. SEE WATER TEMPERATURE CONTROL
SECTION ON PAGE 17 & 19. IF HIGHER PREHEAT TEMPERATURES
ARE NECESSARY TO OBTAIN ADEQUATE BOOSTER OUTPUT, ADD
AN ANTI-SCALD VALVE FOR HOT WATER SUPPLIED TO FIXTURES.
CAUTION: IF BUILDING COLD WATER SUPPLY HAS A BACK-FLOW
PREVENTER, CHECK VALVE OR WATER METER WITH CHECK VALVE,
PROVISIONS FOR THERMAL EXPANSION OF WATER IN THE HOT WATER
SYSTEM MUST BE PROVIDED.
NOTE:CONNECT RETURN LINE FROM HOT
WATER CIRCULATING LOOP (IF USED) TO
COLD WATER INLET LINE.
NOTE:CONNECT RETURN LINE FROM HOT
WATER CIRCULATING LOOP (IF USED) TO
COLD WATER INLET LINE.
WIRING DIAGRAM FOR HEATER TO TANK
LOOP AND/OR HOT WATER LOOP
(IF USED)
*PIPE TO OPEN DRAIN INSTALL IN ACCORDANCE WITH LOCAL CODES

13
DANGER
TEMPERATURE SETTING SHOULD NOT EXCEED
SAFE USE TEMPERATURE AT FIXTURES. SEE
WATER TEMPERATURE CONTROL SECTION ON
PAGE 17 & 19. IF HIGHER PREHEAT
TEMPERATURES ARE NECESSARY TO OBTAIN
ADEQUATE BOOSTER OUTPUT, ADD AN ANTI-
SCALD VALVE FOR HOT WATER SUPPLIED TO
FIXTURES.
ONE OR TWO TEMPERATURE - ONE HEATER MEDIUM TEMPERATURE STORAGE
WITH OR WITHOUT RECIRCULATION
(FOR STORAGE OR INSTANTANEOUS HEATERS ONLY)
TWO TEMPERATURE - TWO PRE-HEATERS HIGH TEMPERATURE STORAGE
WITH OR WITHOUT RECIRCULATION
(FOR STORAGE OR INSTANTANEOUS HEATERS ONLY)
CAUTION: IF BUILDING COLD WATER SUPPLY HAS A BACK-FLOW
PREVENTER, CHECK VALVE OR WATER METER WITH CHECK
VALVE, PROVISIONS FOR THERMAL EXPANSION OF WATER IN
THE HOT WATER SYSTEM MUST BE PROVIDED.
*PIPE RELIEF VALVE TO OPEN DRAIN
NOTE:IF TEMPERED WATER IS
RECIRCULATED, RETURN LINE
SHOULD BE CONNECTED AT POINT “A”.
INSTALL IN ACCORDANCE WITH LOCAL
CODES.

14
TWO TEMPERATURE - THREE HEATERS (TWO PRE-HEATERS/ONE BOOSTER)
WITH OR WITHOUT CIRCULATION
(FOR STORAGE OR INSTANTANEOUS HEATERS ONLY)
TWO TEMPERATURE - TWO HEATERS (ONE PRE-HEATER/ONE BOOSTER HEATER)
WITH OR WITHOUT RECIRCULATION
(FOR STORAGE OR INSTANTANEOUS HEATERS ONLY)
CAUTION: IF BUILDING COLD WATER SUPPLY HAS A
BACK-FLOW PREVENTER, CHECK VALVE OR WATER
METER WITH CHECK VALVE, PROVISIONS FOR
THERMAL EXPANSION OF WATER IN THE HOT WATER
SYSTEM MUST BE PROVIDED.
FOR MULTIPLE HEATER INSTALLATION SEE
MANIFOLD KIT SPECIFICATIONS.
WIRING DIAGRAM FOR FIXTURE OR
BOOSTER LOOP (IF USED) - OTHER
THAN DISHWASHER
* PIPE RELIEF VALVE TO OPEN DRAIN.
** TEMPERATURE SETTING OF PRE-HEATER
SHOULD BE 120°F MIN. OR 150°F MAX.
CONNECT CIRCULATING LINE FROM FIXTURES,
IF USED, TO COLD WATER SUPPLY LINE OF
PRE-HEATER.
CONNECT CIRCULATING LINE OF 180°F OR
BOOSTED WATER, IF USED, TO INLET WATER
LINE TO BOOSTER.
INSTALL IN ACCORDANCE WITH LOCAL CODES.
DANGER
TEMPERATURE SETTING SHOULD NOT EXCEED SAFE USE TEMPERATURE
AT FIXTURES. SEE WATER TEMPERATURE CONTROL SECTION ON PAGE 17
& 19. IF HIGHER PREHEAT TEMPERATURES ARE NECESSARY TO OBTAIN
ADEQUATE BOOSTER OUTPUT, ADD AN ANTI-SCALD VALVE FOR HOT WATER
SUPPLIED TO FIXTURES.

15
DANGER
TEMPERATURE SETTING SHOULD NOT EXCEED SAFE USE TEMPERATURE AT
FIXTURES. SEE WATER TEMPERATURE CONTROL SECTION ON PAGE 17 & 19.
IF HIGHER PREHEAT TEMPERATURES ARE NECESSARY TO OBTAIN ADEQUATE
BOOSTER OUTPUT, ADD AN ANTI-SCALD VALVE FOR HOT WATER SUPPLIED
TO FIXTURES.
ONE OR TWO TEMPERATURE - ONE HEATER MEDIUM TEMPERATURE STORAGE
WITH RECIRCULATED LOOP
(FOR STORAGE OR INSTANTANEOUS HEATERS ONLY)
CAUTION: IF BUILDING COLD WATER SUPPLY HAS A BACK-FLOW
PREVENTER, CHECK VALVE OR WATER METER WITH CHECK VALVE,
PROVISIONS FOR THERMAL EXPANSION OF WATER IN THE HOT WATER
SYSTEM MUST BE PROVIDED.
NOTE:IF TEMPERED WATER IS RECIRCULATED, RETURN LINE SHOULD BE
CONNECTED AT POINT “A”.
NOTE:STORED TEMPERATURE WATER LOOP, IF USED, CONNECT TO COLD
WATER INLET.
NOTES

16
MANIFOLD KITS
Precision cut type “L” all copper manifold kits from your
manufacturer assure water flow balance of all units. Without
this balance, the full water heating and storage potential of the
system cannot be achieved. Plus, the units with the higher water
flow may have a shortened life. Unions shown in piping diagrams
are not included in the manifold kits.
Dimensions shown are for minimum space occupied by the water
heaters assemblies.
Space for the barometric draft control assemblies, combustion
clearances and servicing must be added.

17
PRIOR TO START UP
IMPORTANT
IT IS REQUIRED THAT A QUALIFIED PERSON PERFORM THE
INITIAL FIRING OF THE HEATER. AT THIS TIME THE USER
SHOULD NOT HESITATE TO ASK THE INDIVIDUAL ANY
QUESTIONS WHICH HE MAY HAVE IN REGARD TO THE
OPERATION AND MAINTENANCE OF THE UNIT.
A CHECKLIST AND SERVICE INFORMATION section is included
at the rear of this manual. By using this checklist the user may
be able to make minor operational adjustments and save himself
unnecessary service calls. However, the user should not attempt
repairs which are not listed in this section.
REQUIRED EQUIPMENT AND ABILITY
INSTALLATION OR SERVICE OF THIS WATER HEATER
REQUIRES ABILITY EQUIVALENT TO THAT OF A LICENSED
TRADESMAN IN THE FIELD INVOLVED. PLUMBING, AIR
SUPPLY, VENTING, GAS SUPPLY AND ELECTRICAL WORK
ARE REQUIRED.
Before attempting start-up, thoroughly study and familiarize
yourself with the exact sequence of operation and all other details
on the specific heater being used.
The power burner is equipped with a direct spark ignition system
and automatically sequences prepurge and ignition, senses and
ignites main burner flame and sequences burner operation.
Heater is equipped with an ignition module which locks out after
an unsuccessful ignition attempt. Turn off electric power for ten
seconds before restarting.
Be certain that water heater is full of water, that air is purged from
all lines, no leaks (gas and water) and all inlet water lines are
open.
The following test equipment should be on hand: (all test
equipment must be acclimated to ambient temperature before
calibration and use.)
–CO
2indicator (Fyrite or similar) or O2analyzer
– CO indicator (Monoxor or similar)
– Stack thermometer
– Draft Gauge or inclined manometer
– Two U-tube manometers or calibrated 0-10" and 0-35"
w.c. pressure gauges.
– Combination volt/ammeter.
• Attach a gas pressure gauge or manometer to upstream side
of main gas cock and a gas pressure gauge or manometer to
the manifold pressure tapping.
• Check voltage at disconnect switch to make certain that it
matches that shown on the burner label.
• Apply a few drops of No. 20 SAE non-detergent oil to motor
bearings.
• Drill max. 5/16" hole in breeching as close as possible to flue
connection on heater to install stack thermometer and
combustion analyzing equipment. (See fig. 4).
• You are now ready to begin the burner start up procedure.
Follow the OPERATIONAL PROCEDURE in the OPERATIONAL
AND ADJUSTMENT PROCEDURE section of this manual.
PURGING
Gas line purging is required with new piping or systems in which
air has entered.
CAUTION
PURGING SHOULD BE PERFORMED BY PERSONS
EXPERIENCED IN THIS TYPE GAS SERVICE. TO AVOID RISK
OF FIRE OR EXPLOSION, PURGE DISCHARGE MUST NOT
ENTER CONFINED AREAS OR SPACES WHERE IGNITION
CAN OCCUR. THE AREA MUST BE WELL VENTILATED AND
ALL SOURCES OF IGNITION MUST BE INACTIVATED OR
REMOVED.
WATER TEMPERATURE CONTROL
DANGER
THIS WATER HEATER IS EQUIPPED WITH AN ADJUSTABLE
THERMOSTAT TO CONTROL WATER TEMPERATURE. HOT
WATER TEMPERATURES REQUIRED FOR AUTOMATIC
DISHWASHER AND LAUNDRY USE CAN CAUSE SCALD
BURNS RESULTING IN SERIOUS PERSONAL INJURY AND/
OR DEATH. THE TEMPERATURE AT WHICH INJURY OCCURS
VARIES WITH THE PERSON’S AGE AND TIME OF EXPOSURE.
THE SLOWER RESPONSE TIME OF CHILDREN, AGED OR
DISABLED PERSONS INCREASES THE HAZARDS TO THEM.
NEVER ALLOW SMALL CHILDREN TO USE A HOT WATER TAP,
OR TO DRAW THEIR OWN BATH WATER. NEVER LEAVE A
CHILD OR DISABLED PERSON UNATTENDED IN A BATHTUB
OR SHOWER.
THE WATER HEATER SHOULD BE LOCATED IN AN AREA
WHERE THE GENERAL PUBLIC DOES NOT HAVE ACCESS
TO SET TEMPERATURES.
SETTING THE WATER HEATER TEMPERATURE AT 120°F
WILL REDUCE THE RISK OF SCALDS. Some states or provinces
require settings at specific lower temperatures.
Below you will find listed Table 5 the approximate time-to-burn
relationship for normal adult skin. Short repeated heating cycles
caused by small hot water uses can cause temperatures at the
point of use to exceed the thermostat setting by up to 20°F (11°C).
If you experience this type of use, you should consider using
lower temperature settings to reduce scald hazards.

18
OPERATIONAL AND ADJUSTMENT PROCEDURE (INITIAL START UP)
FOR YOUR SAFETY READ BEFORE LIGHTING
WARNING: IF YOU DO NOT FOLLOW THESE INSTRUCTIONS
EXACTLY, A FIRE OR EXPLOSION MAY RESULT CAUSING PROPERTY
DAMAGE, PERSONAL INJURY OR LOSS OF LIFE.
A. THIS APPLIANCE DOES NOT HAVE A PILOT. IT IS
EQUIPPED WITH AN IGNITION DEVICE WHICH
AUTOMATICALLY LIGHTS THE BURNER. DO NOT TRY
TO LIGHT BURNER BY HAND.
B. BEFORE OPERATING SMELL ALL AROUND THE
APPLIANCE 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.
• DO NOT 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 DEPARTMENT.
C. USE ONLY YOUR HAND TO PUSH IN OR TURN THE
GAS CONTROL KNOB. NEVER USE TOOLS. IF THE
KNOB WILL NOT PUSH IN OR 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.
D. 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.
E. DO NOT OPERATE APPLIANCE UNLESS UNIT IS
FILLED WITH WATER AND INLET LINES ARE FULLY
OPEN.
OPERATING INSTRUCTIONS
1. STOP! READ THE SAFETY INFORMATION
ABOVE ON THIS LABEL.
2. REMOVE APPLIANCE THERMOSTAT COVER. ROTATE
THE THERMOSTAT DIAL COUNTERCLOCKWISE
TO LOWEST SETTING.
3. TURN OFF ALL ELECTRIC POWER TO THE
APPLIANCE.
4. THIS APPLIANCE IS EQUIPPED WITH AN IGNITION
DEVICE WHICH AUTOMATICALLY LIGHTS THE
BURNER. DO NOT TRY TO LIGHT THE BURNER BY
HAND.
5. TURN GAS VALVE CONTROL KNOB CLOCKWISE
T O “OFF” (FIG.A). NOTE: HALFWAY THRU THE TURN,
THE KNOB WILL POP UP. CONTINUE TO TURN UNTIL
KNOB LOCKS INTO THE “OFF” POSITION.
6. WAIT FIVE (5) MINUTES TO CLEAR OUT ANY GAS. IF
YOU THEN SMELL GAS:
STOP! FOLLOW “B” IN THE SAFETY
INFORMATION ABOVE IN THIS LABEL. IF
YOU DON’T SMELL GAS, GO TO NEXT
STEP.
7. TURN GAS VALVE CONTROL KNOB
COUNTERCLOCK WISE TO “ON” (FIG. B). NOTE
HALFWAY THRU THE TURN DEPRESS THE KNOB
AND CONTINUE TURNING UNTIL IT LOCKS INTO THE
“ON” POSITION.
8. TURN ON ALL ELECTRIC POWER TO THE
APPLIANCE.
9. SET THERMOSTAT TO DESIRED SETTING. HEATER
WILL AUTOMATICALLY BEGIN OPERATION. MOTOR
WILL RUN APPROXIMATELY 45 SECONDS
(PREPURGE), THEN MAIN BURNER IGNITION WILL
OCCUR.
10.REPLACE THERMOSTAT CONTROL COVER.
11. HEATER IS EQUIPPED WITH AN IGNITION MODULE
WHICH LOCKS OUT AFTER AN UNSUCCESSFUL
IGNITION ATTEMPT. IF MAIN BURNER DOES NOT
LIGHT DURING THIS PERIOD, REPEAT STEPS 2
THRU 9. IF THE APPLIANCE WILL NOT OPERATE,
FOLLOW THE INSTRUCTIONS, “TO TURN OFF GAS
TO APPLIANCE”, AND CALL YOUR SERVICE
TECHNICIAN OR GAS SUPPLIER.
1. REMOVE THERMOSTAT CONTROL COVER.
2. SET THE THERMOSTAT TO LOWEST SETTING.
3. TURN OFF ALL ELECTRIC POWER TO THE APPLIANCE IF SERVICE IS TO BE PERFORMED.
4. TURN GAS VALVE CONTROL KNOB CLOCKWISE TO “OFF”. REFER TO STEP 5 OF “OPERATING
INSTRUCTIONS” ABOVE.
5. REPLACE THERMOSTAT CONTROL COVER.
TO TURN OFF GAS TO APPLIANCE

19
TABLE 5
Temperature Time to Produce 2nd & 3rd
Setting Degree Burns on Adult Skin
o180°F (82°C) Nearly instantaneous
170°F (77°C) Nearly instantaneous
160°F (71°C) About 1/2 second
150°F (65°C) About 1-1/2 seconds
140°F (60°C) Less than 5 seconds
130°F (54°C) About 30 seconds
120°F (49°C) More than 5 minutes
Valves for reducing point-of-use temperature by mixing cold and
hot water are available. Also available are inexpensive devices
that attach to faucets to limit hot water temperatures. Contact a
licensed plumber or the local plumbing authority.
The water temperature is controlled by a thermostat, fig. 1, which
has two sensing elements. One sensor is located near the top of
the tank and the other is near the center. The thermostat is set in
the lowest position before the heater leaves the factory.
The thermostat temperature dial, fig. 1, is accessible by removing
the control cover. The dial is adjustable and may be set for 1200
(49°C) to 1800F (82°C) water temperature, but 1200F (49°C) is
the recommended starting point. It is suggested the dial be placed
on the lowest setting which produces an acceptable hot water
supply. This will always give the most energy efficient operation.
The temperature control has a 40F fixed differential.
ADJUSTMENT PROCEDURE
1. Check gas line pressure and manifold pressure (table 6) and
adjust as required.
2. Check barometric damper for proper operation. Parts must
move freely.
3. Allow the unit to operate for 15 minutes. Draw hot water from
the heater or storage tank to continue main burner operation.
4. Determine heat input rate:
• The input rate for natural gas models can be estimated
by timing the meter, if no other appliances are operating.
*With a stopwatch, or a wristwatch, which can display
the time in seconds, read the gas meter and measure
the amount of time required for the heater to consume 5
cubic feet of gas. The actual rate may then be estimated
by using the formula below:
Input Rate (Btuh) =
Actual Heating Value of Gas (Btu/ft3) x 18000
number of seconds to use 5 ft3of gas
The approximate heating value of natural gas is 1050 Btu/ft3.
Obtain the actual heating value of the gas at the site from the
gas utility. Propane (L.P.) gas has an approximate heating
value of 2500 Btu/ft3.
For example: Assume a ***81-270, firing on natural gas,
consumes 5 ft3of gas in 71.0 seconds.
The estimated input rate is:
(1050) x (18000) = 266000 Btuh
71.0
This is an acceptable input rate for a ***81-270, installed at
an altitude up to 2000 feet, as it is within 2% of the rated input.
For installations at higher altitudes, the input will be less for
the reasons explained in the FOREWORD.
• The input may be adjusted by adjusting the pressure regulator.
Remove the top cap to expose the adjustment screw. Turning
the screw in increases the gas pressure and backing the screw
out decreases the pressure. Do not turn the adjusting screw
in past the point where no further increase in pressure is noted.
The manifold pressure is measured at the manifold pressure tap,
see Figure 7, and should be used as a reference point for making
pressure regulator adjustments. Table 6 gives the design manifold
pressures for each model. Increase or reduce the pressure as
required to obtain the rated input.
If an acceptable rate cannot be achieved by adjusting the pressure
regulator (manifold pressure), first check to be certain that the
gas supply pressure to the unit is adequate. If the supply pressure
is inadequate, a different burner orifice may be required. Obtain
from the utility the heating value and specific gravity of the gas at
the site. Provide this information and the altitude of the site to
the manufacturer to obtain a larger orifice size.
WARNING
UNDER NO CIRCUMSTANCES SHOULD THE INPUT RATE
EXCEED THE INPUT RATE SHOWN IN THE HEATER RATING
PLATE. OVERFIRING COULD RESULT IN DAMAGE OR
SOOTING OF THE HEATER.
5. Make combustion measurements and corresponding air shutter
adjustments per table 6. Combustion results from table 6 are
for natural gas models.
• Proceed with CO2test of the flue gases with an Orsat or
other similar combustion test equipment. If the CO2
content is within range (see table 6) no adjustment of
the air shutter is required. Flue gas temperature and
CO2measurements should be repeated 3 times to
ensure accurate readings.
• Check the flue gas temperature ahead of the barometric
damper. See table 6 (net temp. = gross temp. = ambient
temp.)
• Check breeching pressure and the barometric damper
control to make sure it operates freely and there is no
discharge of flue products into the room. See “Venting”
section.
TABLE 6
NOMINAL START-UP SPECIFICATIONS
*** *** *** ***
MODEL 81-140 81-199 81-270 81-370
Max. Gas Line Press.(W.C.) Nat. Gas - 10.5”W.C./Prop. Gas - 13.0”
Manifold Press. (W.C.)
Natural Gas 3.5 3.5 3.5 3.5
Propane Gas 3.5 3.5 3.5 3.5
Orifice
Natural Gas 0.24 0.308 0.386 0.532
Propane Gas 0.209 0.257 0.302 0.368
Air Shutter Setting No.
Natural Gas 2.5 5.75 4 6.5
Propane Gas 4.5 10 4 8.5
CO2% 9.2% 9.8% 7.5% 8.0%
CO Parts Per Million <200 <200 <200 <200
Gross Stack Temp. (°F) 305 338 468 540
Breeching Press.(inches W.C.) Ranges from - 0.30 to - 0.05 Inches Water Column

20
6.Check main burner operation by cycling on and off the
thermostat dial several times. Wait 1 minute between cycles for
regulators and sequencing to reset.
7. When all adjustments are satisfactory:
• Fill in part no. 170037 “Start-up” form.
• Adjust thermostat temperature dial to deliver desired
water temperature at point of use.
• For subsequent normal starting and shutoff procedure,
see OPERATIONAL PROCEDURE.
MAINTENANCE
MAINTENANCE SCHEDULE
Water heater maintenance includes periodic tank flushing and
cleaning, and removal of lime scale. The power burner should
be inspected and adjusted to maintain proper combustion. Refer
to table 7. A periodic inspection of the venting system and
barometric damper should be made. Where used, the water
heating system circulating pump should be oiled.
Following are the instructions for performing some of the
recommended maintenance. Power burner inspection and
adjustment should be performed by a competent technician.
TABLE 7
RECOMMENDED MAINTENANCE SCHEDULE
FOR THE ***81-140 THRU ***81-370 HEATER
COMPONENTS OPERATION INTERNAL REQUIRED
Flushing Monthly
Sediments
Tank Removal Semi-Annually
Lime Scale Un•Lime
Removal As Required Delimer
Relief Valve Inspect Semi-Annually
Circulating Pump SAE No. 20
and Power Oiling Quarterly Non-Detergent
Burner Motor(1) Motor Oil
Power Burner Combustion Test
and Ignition Inspection Kit and Test
Device (2) and Adjustment Semi-Annually Specifications
Main Burner Inspect Semi-Annually
Vent System and
Barometric Draft
Damper Inspect Semi-Annually Gauge
Anode(s) Inspect Annually
FLUSHING
1. Turn off the heater electrical disconnect switch.
• For convenience, the switch on the outside of the control
compartment can be used.
2. Open the drain valve and allow water to flow until it runs clean.
3. Close the drain valve when finished flushing.
4. Turn on the heater electrical disconnect switch.
DRAINING
The heater must be drained if it is to be shut down and exposed
to freezing temperatures. Maintenance and service procedures
may also require draining the heater.
1. Turn off the heater electrical disconnect switch.
2. Close the cold water inlet valve to heater.
3. Open a nearby hot water faucet to vent the system.
4. Open the heater drain valve.
5. If the heater is being drained for an extended shutdown, it is
suggested the drain valve be left open during this period.
Reverse these instructions when restoring hot water service.
SEDIMENT REMOVAL
Waterborne impurities consist of fine particles of soil and sand
which settle out and form a layer of sediment on the bottom of
the tank.
For convenience, sediment removal and lime scale removal should
be performed at the same time.
LIME SCALE REMOVAL
The amount of calcium carbonate (lime) released from water is
in direct proportion to water temperature and usage. The higher
the water temperature or water usage, the more lime deposits
are dropped out of the water. This is the lime scale which forms
in pipes, heaters and on cooking utensils.
Lime accumulation not only reduces the life of the equipment
but also reduces efficiency of the heater and increases fuel
consumption.
The usage of water softening equipment greatly reduces the
hardness of the water. However, this equipment does not always
remove all of the hardness (lime). For this reason it is
recommended that a regular schedule for deliming be
maintained.
The depth of lime build-up should be measured periodically.
Heaters will have about 3" of lime build-up when the level of lime
has reached the bottom of the cleanout opening or about 1" of
lime build-up if it has reached the drain valve opening. A schedule
for deliming should be set up, based on the amount of time it
would take for a 1" build-up of lime.
Example 1:Initial inspection, six months after installation, shows
1/2" of lime accumulation. Therefore, the heater can be
delimed once a year.
Example 2:Initial inspection, six months after installation, shows
2" of lime accumulation. Therefore, the heater should
be delimed every 3 months.
Sediment and lime scale removal may be accomplished through
the cleanout opening furnished on the heater, see DRAIN VALVE
AND ACCESS PANELS. The heater must be drained, see
DRAINING, before removing cleanout cover on tank.
To dissolve and remove the more stubborn mineral deposits,
UN•LIME®Professional Delimer should be used.
UN•LIME Delimer is an easy-to-handle patented food grade acid
formulated specifically for lime scale removal from all types of
water using equipment. Available in 1 gallon (part no. 4763) and
5 gallon (part no. 4813) sizes. Hydrochloric base acids are not
recommended for use on glass-lined tanks.
Form No. 4800, entitled “Why, When and How”, describes tank
cleaning methods and materials. UN•LIME and the booklet may
be obtained through your dealer or distributor.