A.O. Smith BTPV-540A, 650A, 740A User Manual
MODELS BTP(V)-540A, 650A AND 740A
COMMERCIAL GAS, GLASS-LINED, TANK-TYPE LOW NOx
WATER HEATER
• INSTALLATION • OPERATION • MAINTENANCE • LIMITED WARRANTY
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PRINTED IN U.S.A. 1004
TEXT PRINTED OR OUTLINED IN RED CONTAINS INFORMATION RELATIVE TO YOUR SAFETY.
READ THOROUGHLY BEFORE INSTALLING AND USING
THIS APPLIANCE.
A DIVISION OF A.O.SMITH CORPORATION
MCBEE, SOUTH CAROLINA
www.aosmithwaterheaters.com
PLACE THESE INSTRUCTIONS ADJACENT TO HEATER AND
NOTIFY OWNER TO KEEP FOR FUTURE REFERENCE.
1
CAUTION
PLEASE
PART NO. 195033-000
ROUGH-IN DIMENSIONS
STANDARD BAROMETRIC DRAFT CONTROL
BTP MODELS
HORIZONTAL & DIRECT VENTING
BTPV MODELS
MAXIMUM TOTAL 75 EQUIVALENT
FEET INTAKE AND EXHAUST
ALLOWED.
ALL DIMENSIONS IN INCHES (MILLIMETERS)
Models A B C D E F G H I Conn. Ship. Wt.
BTP(V)-540A
BTP(V)-650A
BTP(V)-740A
*Minimum gas supply pipe is 1 1/4”, reference Table 7 for gas supply pipe size.
Models U.S. Gals. (Litres) Nat. 100°F Rise 140°F Rise 60Hz 1 Phase
BTP(V)-540A 85 (261) 540,000 523.6 374
BTP(V)-650A 85 (261) 650,000 630 450
BTP(V)-740A 85 (261) 740,000 718 512
Based on 80% thermal efficiency obtained in A. O. Smith engineering laboratories.
NOTE: To compensate for the effects of high altitude areas above 2000 feet, recovery ratings should be reduced approximately
4% for every 1000 feet above sea level.
80 3/4 73 32 1/4 9 6 26 1/2 93 29 1/2 48 1/2 1* 950
2,051 1,854 819 229 152 673 2,362 749 1,232 25.4 431 kg
80 3/4 73 32 1/4 9 8 26 1/2 93 29 1/2 48 1/2 1* 950
2,051 1,854 819 229 203 673 2,362 749 1,232 25.4 431 kg
80 3/4 73 32 1/4 9 8 26 1/2 93 29 1/2 48 1/2 1* 950
2,051 1,854 819 229 203 673 2,362 749 1,232 25.4 431 kg
Storage Input Rating Recovery Rating Recovery Rating Current Draw
Capacity BTU/HR. GPH GPH 120V
Gas Approx.
FOREWORD
The design of the BTP 540A through 740A models complies
with ANSI Z21.10.3/CSA 4.3 as an automatic circulating tank
and an automatic instantaneous type heater. The BTPV 540A
through 740A models are designed for sidewall venting and
direct venting applications and are certified under UL 795.
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.
6.0 Amps
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.
THE HEATER IS DESIGNED TO OPERATE ONLY ON NATURAL
GAS.
THESE HEATERS MUST NOT BE INSTALLED ON
COMBUSTIBLE FLOORS.
2
In addition to these instructions, the equipment shall be installed
in accordance with those installation regulations 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.
TABLE OF CONTENTS
ROUGH-IN-DIMENSIONS ........................................................................ 2
FOREWORD ....................................................................................... 2,3
TABLE OF CONTENTS ........................................................................... 3
GENERAL SAFETY INFORMATION ....................................................... 3
Precautions ...................................................................................3
Liquid Petroleum Models ................................................................3
Chemical Vapor Corrosion ........................................................ 3,4
Improper Combustion .................................................................... 4
EXTENDED NON-USE PERIODS ............................................................. 4
Cathodic Protection ....................................................................... 4
Insulation Blankets ......................................................................... 4
High Altitude Installations .............................................................. 4
FEATURES ............................................................................................. 4
Low Emmission Control .................................................................4
High Limit Switch (E.C.O.) ......................................................... 4,5
Dishwashing Machine Requirement ............................................. 5
INSTALLATION INSTRUCTIONS ............................................................. 5
Required Ability ............................................................................. 5
Uncrating ....................................................................................... 5
Locating the Heater ................................................................... 5,6
Hard Water ....................................................................................6
Clearances .................................................................................... 6
Air Requirements ........................................................................... 6
Venting....................................................................................... 6,7
Vertical Venting - For BTP Models ................................................7
Horizontal (Side-wall) Venting - For BTPV Models .................. 7,8
Direct Venting - For BTPV Models .......................................... 9-11
Gas Piping ............................................................................. 11-12
Gas Meter Size ............................................................................12
Gas Pressure Regulation ............................................................12
Gas Valves ............................................................................ 12,13
Water Line Connections ..............................................................13
Thermometers ............................................................................. 13
Relief Valve .................................................................................13
INSTALLATION DIAGRAMS ........................................................... 14-17
Manifold Kits ................................................................................ 18
In the absence of local codes, the installation must conform with
the instructions as outlined in the latest publication of National
Fuel Gas Code (NFPA-54/ANSI Z223.1) and National Electric
Code (NFPA-70). These manuals can be purchased from the
Canadian Standards Association Laboratories, 8501 East
Pleasant Valley Road, Cleveland, OH 44131, National Fire
Protection Association, 1 Batterymarch Park, Quincy MA 02269.
PAGEPAGE
Heater Wiring ...............................................................................19
START UP ............................................................................................ 19
Important ...................................................................................... 19
Filling ............................................................................................ 19
Purging .........................................................................................19
Wiring Diagram ...................................................................... 20,21
Lighting and Operating Label ...................................................... 22
Sequence of Operation ............................................................... 23
Water Temperature Control .........................................................23
Adjustment Procedure (Initial Start-Up) ................................ 23,24
Adjustment Procedure for Fire-Rate, Low Nox and
High Elevation (Fine-Tune) .................................................... 24-26
GENERAL INFORMATION ....................................................................27
Power Burner .............................................................................. 27
Thermostat ..................................................................................27
High Limit ...................................................................................... 27
MAINTENANCE .................................................................................... 27
General ........................................................................................27
Maintenance Schedule ................................................................27
Electrical Servicing ...................................................................... 27
Flushing ....................................................................................... 27
Draining ........................................................................................ 28
Sediment Removal ....................................................................... 28
Lime Scale ................................................................................... 28
Relief Valve ........................................................................... 28,29
Circulating Pump .......................................................................... 29
Low Emission Power Burner ...................................................... 29
Cleaning Flues ............................................................................. 29
Barometric Draft Control ............................................................. 29
Vent System ................................................................................ 29
CHECKLIST AND SERVICE INFORMATION .................................... 29-30
TROUBLESHOOTING ..................................................................... 30-32
Replacement Parts ...................................................................... 32
WARRANTY ........................................................................................ 33
NOTES ........................................................................................... 34,35
GENERAL SAFETY INFORMATION
PRECAUTIONS
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.
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.
LIQUID PETROLEUM MODELS
WARNING
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.
BTP(V)-540A, 650A & 740A models are not available for use
with Liquefied Petroleum or LP gas. If you have obtained a
BTP(V)-540A, 650A or 740A model with the intent to use it
with Liquefied Petroleum, LP gas - STOP! Immediately contact
your dealer to obtain a correct model.
CHEMICAL VAPOR CORROSION
WARNING
CORROSION OF THE FLUEWAYS AND VENT SYSTEM MAY
OCCUR IF AIR FOR COMBUSTION CONTAINS CERTAIN
CHEMICAL VAPORS. SUCH CORROSION MAY RESULT IN
FAILURE AND RISK OF ASPHYXIATION.
Spray can propellants, cleaning solvents, refrigerator and air
conditioning refrigerants, swimming pool chemicals, calcium
3
and sodium chloride (water softener salt), waxes, and process
chemicals are 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 no 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).
2. INSULATION BLANKETS CAN RESTRICT THE AIR FLOW
NEEDED FOR PROPER OPERATION OF THE COMBUSTION
SYSTEM AND COULD RESULT IN FIRE, ASPHYXIATION,
SERIOUS PERSONAL INJURY OR DEATH.
WARNING
FAILURE TO FOLLOW THESE INSTRUCTIONS CAN RESULT IN
SERIOUS PERSONAL INJURY OR DEATH.
IMPROPER COMBUSTION
WARNING
ATTIC AND OR EXHAUST FANS OPERATING ON THE PREMISES
WITH A WATER HEATER CAN RESULT IN CARBON MONOXIDE
POISONING AND DEATH.
OPERATION OF 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
VENTILATION AIR, ADEQUATE AIR FOR COMBUSTION AND
VENTILATION MUST BE PROVIDED FOR SAFE OPERATION.
EXTENDED NON-USE PERIODS
CATHODIC PROTECTION
CAUTION
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 a
hot water faucet be opened for several minutes 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 not smoking or open flame near the
faucet at the time it is open.
INSULATION BLANKETS
WARNING
INSULATION BLANKET AVAILABLE TO THE GENERAL PUBLIC
FOR EXTERNAL USE ON GAS WATER HEATERS ARE NOT
APPROVED FOR USE ON YOUR A.O. SMITH WATER HEATER.
THE PURPOSE OF AN INSULATION BLANKET IS TO REDUCE
THE STANDBY HEAT LOSS ENCOUNTERED WITH STORAGE
TANK WATER HEATER. YOUR A.O. SMITH WATER HEATER MEETS
OR EXCEEDS THE ASHRAE/IES 90.1B 2001 STANDARDS WITH
RESPECT TO INSULATION AND STANDBY LOSS
REQUIREMENTS, MAKING AN INSULATION BLANKET
UNNECESSARY. THE USE OF INSULATION BLANKETS IN
CONJUNCTION WITH AN A.O. SMITH WATER HEATER WILL
ALSO VOID THE SMITH WARRANTY FOR THE FOLLOWING
REASONS:
HIGH ALTITUDE INSTALLATIONS
Your A.O. Smith water heater has been designed to operate at
altitudes below 2000 Ft. (609.6 m), for appliance installation
locations with elevations above 2000 Ft. (609.6 m), special
considerations need to be taken. Adjustments for high altitude
can only be made by an A.O. Smith authorized BTP Start-up
Agent. To ensure your water heater operates properly at high
elevation, an A.O. Smith authorized BTP Start-up Agent will
readjust the air-intake damper setting and the gas manifold
pressure (if required).
NOTE: Some gas utility companies derate the heating value of
the supplied gas at high elevation. Your authorized start-up agent
must adjust for actual heating value of the gas at the time of start
up.
FEATURES
LOW EMISSION CONTROL
Your A.O. Smith water heater has been designed to comply with
standards established by California South Coast Air Quality
Management District (SCAQMD), the most stringent emissions
control agency in the nation. To ensure compliance with SCAQMD
Rule 1146.2, your heater is equipped with an internal recirculation
premix power burner, and must be started/adjusted by an
A.O. Smith Authorized BTP Start-Up Agent.
HIGH LIMIT SWITCH (E.C.O.)
The dual bulb controller also 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 20°F
(11°C) approx. and the high limit reset button on front of limit
control is depressed, see Figure 1.
1. INSULATION BLANKETS COVER IMPORTANT OPERATING
INSTRUCTIONS AND SAFETY LABELS.
FIGURE 1.
4
Continued manual resetting of high limit control, preceded by
higher than usual water temperature is evidence of high limit
switch operation. The following are possible reasons 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.
• An improper thermostat setting for a short repetitive usage
pattern may lead to a stacking effect. This causes a
temperature gradient increasing from the bottom to the top of
the tank. It is possible that the water at the high limit switch
sensor could reach its maximum temperature before the water
temperature at the thermostat reaches the dial setting,
causing the high limit switch to activate.
• A warming of ambient conditions associated with seasonal
change could magnify the stacking process described above
to the point where high limit switch operation would occur.
Contact your dealer or servicer if continued high limit switch
operation occurs.
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 180°F (82°C)
line to the dishwashing machine, and should be adjusted to
deliver water between these limits.
The National Sanitation Foundation also recommends
circulation of 180°F (82°C) 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 180°F (82°C) 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. NOTE: AUTHORIZED START-UP IS REQUIRED.
LOCATING THE HEATER
When installing the heater, consideration must be given to proper
location. Location selected should be as close to the stack
chimney as practicable, with adequate air supply and as
centralized with the piping system as possible.
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 ARE HEAVY
AND TRAVEL ALONG THE FLOOR AND MAY BE IGNITED BY THE
HEATER’S IGNITER OR MAIN BURNER FLAMES CAUSING FIRE
OR EXPLOSION. SOME LOCAL CODES PERMIT OPERATION OF
GAS APPLIANCES IF INSTALLED 18 INCHES OR MORE ABOVE
THE FLOOR. THIS MAY REDUCE THE RISK IF LOCATION IN SUCH
AN AREA CANNOT BE AVOIDED.
THE HEATER SHALL BE LOCATED OR PROTECTED SO IT IS
NOT SUBJECT TO PHYSICAL DAMAGE BY A MOVING VEHICLE.
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 MUST NOT BE LOCATED IN AN AREA WHERE IT
WILL BE SUBJECT TO FREEZING.
LOCATE IT NEAR A FLOOR DRAIN. THE HEATER SHOULD BE
LOCATED IN AN AREA WHERE LEAKAGE FROM THE HEATER
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
DRAIN PAN SHOULD BE INSTALLED UNDER THE HEATER. Such
pans should be fabricated with sides at least 2” (50.8 mm) deep,
with length and width at least 2” (50,8 mm) greater than the
diameter of the heater and must be piped to an adequate drain.
THE PAN MUST NOT RESTRICT COMBUSTION AIRFLOW.
Water heater life depends upon water quality, water pressure
and the environment in which the water heater is installed. Water
heaters are sometimes installed in locations where leakage
may result in property damage, even with the use of a drain pan
piped to a drain. However, unanticipated damage can be reduced
or prevented by a leak detector or water shut-off device used in
conjunction with a piped drain pan. These devices are available
from some plumbing supply wholesalers and retailers, and
detect and react to leakage in various ways:
UNCRATING
The heater is shipped in standard form for vertical venting with a
barometric draft control assembly in a separate carton.
Optional horizontal vent models are shipped with one (1) exhaust
vent hood and one (1) flue reducer in a separate carton. Optional
direct vent models are shipped with two (2) vent hoods in separate
cartons. The exhaust vent hood carton contains one (1) exhaust
vent hood and one (1) flue reducer. The intake vent hood carton
contains one (1) intake vent hood and one (1) inlet adapter. All
parts should be installed as received without alteration.
• Sensors mounted in the drain pan that trigger an alarm or turn
off the incoming water to the water heater when leakage is
detected.
• Sensors mounted in the drain pan that turn off the water supply
to the entire home when water is detected in the drain pan.
• Water supply shut-off devices that activate based on the water
pressure differential between the cold water and hot water
pipes connected to the water heater.
• Devices that will turn off the gas supply to a gas water heater
while at the same time shutting off its water supply.
5
Units, which are to be installed on combustible flooring, must
be supported by a full layer of hollow concrete blocks, from
8” (203.2 mm) to 12” (304.8 mm) thick and extending
12” (304.8 mm) 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 Figure 2.
NOTE: If electrical conduits run under the floor of the proposed
heater location, insulate the floor as recommended above.
For appliances installation locations with elevations above 2000
feet (609.6 m), refer to HIGH ALTITUDE INSTALLATIONS section.
PROPER INSTALLATION ON COMBUSTIBLE FLOORING
FIGURE 2.
HARD WATER
Where hard water conditions exist, water softening or the
threshold type of water treatment is recommended. This will
protect the dishwasher, Coffee urns, water heaters, water piping
and other equipment.
See MAINTENANCE section for details of tank cleanout
procedure.
CLEARANCES
These heaters are designed for installation on non-combustible
flooring in an alcove with clearances to combustible construction
of 6” (152.4 mm) from the sides and rear, 24” (610 mm) from the
top with a 6” (152.4 mm) minimum between vent pipe and ceiling.
Minimum clearance from flue pipe to combustible material is 6”
(152.4 mm), see Figure 3.
A clearance of 30” (762 mm) shall be maintained from
serviceable parts, such as power burners, relief valves flue
baffles, thermostats or drain valves.
AIR REQUIREMENTS
KEEP APPLIANCE AREA CLEAR AND FREE OF 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
CARBONING OR SOOTING OF THE COMBUSTION CHAMBER,
BURNERS AND FLUE TUBES AND CREATES A RISK OF
ASPHYXIATION.
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
and ventilation.
If the unconfined space is within a building of tight construction,
(building using the following construction: weather stripping,
heavy insulation, caulking, vapor barrier, etc.), air for combustion
and ventilation must be obtained from outdoors or spaces freely
communicating with the 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 (304.8 mm) OF THE ENCLOSURE TOP
AND ONE IN OR WITHIN 12 INCHES (304.8 mm) 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.
PROPER INSTALLATION CLEARANCES
FIGURE 3.
If the confined space is within a building of tight construction, air
for combustion and ventilation must be obtained from outdoors.
When directly communication 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.
VENTING
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.
6
Heater must be protected from freezing downdrafts during
shutdown periods.
The BTP 540A, 650A and 750A water heater are classified as a
category I appliance (non-positive vent pressure, noncondensing) when installed with the supplied barometric draft
control assembly in a vertical vent installation.
The BTPV 540A through 740A heater is classified as a category
III appliance (positive vent pressure, non-condensing) when
installed with supplied sidewall vent kits or direct vent kit.
All regulations pertaining to the venting of these heaters must
be followed.
The following vent installation instructions cover vertical,
horizontal, and direct vent applications.
VERTICAL VENTING - FOR BTP MODELS
BAROMETRIC DRAFT CONTROL ASSEMBLY
A double-acting barometric draft control assembly is provided
with any unit intended for chimney venting. The purpose of this
draft control is twofold. During downdrafts it acts as a pressure
relief control to prevent the downdraft from blowing into the heater.
It also allows for makeup air to enter the chimney without being
drawn through the heater. In both cases the control prevents the
heater performance from being adversely affected by conditions
within the chimney.
NOTE: A NEGATIVE DRAFT MUST BE MAINTAINED IN VENTING.
A negative draft of 0.02” to 0.04” w.c. Must be maintained in
venting system. Measure draft at the location illustrated in
Figure 4. Adjust the control counter-weights if necessary as
shown in the MAINTENANCE portion of this manual.
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 ¼ 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, see Figure 4.
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
direction in which the outlet to the draft controls assembly faces
is arbitrary. 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.
Damper or other obstructions must not be installed between the
heater and the barometric draft control assembly.
Do not adjust settings on gate.
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.
VENT CONNECTIONS
Vent connections must be made to an adequate stack or chimney.
Refer to the National Fuel Gas Code or to the vent pipe
manufacturer’s gas vent and chimney sizing table to properly
design and size the venting system. Refer to Table 1 for the vent
pipe size required for installation to the barometric draft control
assembly outlet.
TABLE 1.
Model Flue Outlet
BTP-540A 9” (228.6 mm)
BTP-650A 9” (228.6 mm)
BTP-740A 9” (228.6 mm)
Single-wall or type B venting may be used with these heaters in
vertical vent installations. All local and utility regulations on
venting must be followed.
FIGURE 4.
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.
WARNING
Failure to correct back drafts may cause air contamination
and unsafe conditions.
Do not connect the heater to a common vent or chimney with
solid fuel burning equipment. This practice is prohibited by
many local building codes as is the practice of venting gas fired
equipment to the ductwork of ventilation systems.
Connectors shall not be connected to a chimney, vent or venting
system served by a power exhauster, unless the connection is
made on the negative pressure side of the exhauster.
Do not connect any heater vented by natural draft to any vent
serving mechanical draft equipment operating under positive
vent pressure such as category III or category IV appliances.
HORIZONTAL (SIDE-WALL) VENTING -
FOR BTPV MODELS
An exhaust vent hood, vent hood and a flue reducer are supplied
with any unit intended for through-the-wall horizontal venting.
These parts must be installed without alteration. The vent hood
adapter is designed for use with Selkirk Metalbestos Model PS
or Model G venting, see Figure 7 on page 10.
7
Refer to Table 2 for limitations of venting system design for
horizontal venting.
TABLE 2
BTPV-540A-740A
Flue Outlet Dia. (Inches/mm) 9” (228.6)
Flue Reducer 9” x 8”
Dimensions -Supplied (Inches/mm) 228.6 x 203.2
Minimum Outlet Vent Dia. (Inches/mm) 8” (203.2)
Maximum Number 90° 4
Of Elbows 45° 8
Maximum Total Vent System 75
Length, Equiv. Feet/Meters (23 m)
5. Shall not be closer than 3 feet (0.9 m) from the inside corner
of an L- shaped structure.
6. Shall be located above the snow line in geographical areas
where snow accumulates.
VENT SYSTEM INSTALLATION
This heater is a category III appliance when horizontally vented
through a wall using the supplied sidewall vent terminal. All
national and local codes pertaining to the installation of such
venting systems must be followed.
Horizontal portions of the vent system must be installed with a
minimum upward slope of 1/4” per foot of length.
When calculating the equivalent length of a venting system each
90° elbow is equivalent to 10 feet (3 m) of straight pipe. In no
case 45° elbow is equivalent to 5 feet (1.5 m) of straight pipe. In
no case may the sum of the straight pipe lengths and the
equivalent length of the elbows exceeds 80 feet (24.3 m).
Note the minimum vent diameter in Table 2.
Refer to Table 3 for the correct vent terminal size for each heater.
The dimensions noted in Table 3 refer to Figure 5.
TABLE 3
Heater Terminal Rough-In
Model Model A B C D Dimensions
BTPV
540A- VH-1-8” 19-7/8” 13” 10-9/16” 8-5/8” 11-1/16”
740A
All joints and seams in the venting system must be sealed gas
tight. If a silicone sealer is used, it must have a continuous
temperature rating of at least 500°F (260°C); Dow Corning
736 or equivalent must be used.
CAUTION
Use only the vent hood supplied with this kit. Only supplied
hood provides required clearances from combustibles, both
through the wall and the exterior siding. Termination of a
sidewall vent system with a device other than the supplied
vent hood could affect system performance and result in a
safety hazard.
IMPORTANT
Plan the layout of the vent system backward from the vent
termination to the water heater.
1. Use the layout of the vent system backward from the vent
termination to the water heater.
BEWARE OF CONCEALED WIRING AND PIPING INSIDE OF
WALL. REFER TO TABLE 5 FOR THE MAXIMUM WALL
THICKNESS “B” FOR EACH MODEL.
2. Slide hood through opening from outside. Fasten hood to
exterior wall with anchors and screws supplied.
FIGURE 5
Use only the sidewall vent terminal supplied with the heater.
These terminals are specifically listed for use on these
A.O. Smith heaters.
VENT TERMINAL LOCATIONS-EXHAUST
When considering location for sidewall vent terminals refer to
the latest edition of the National Fuel Gas Code which
recommends that vent terminals:
1. Shall be located not less than 12” (304.8 mm) above grade.
2. Shall be located not less than 7 feet (2.1 m) above grade
when adjacent to a public walkway.
3. Shall terminate at least 3 feet (0.9 m) above any forced air
inlet within 10 feet (3 m).
4. Shall terminate at least 4 feet (1.2 m) below, 4 feet (1.2 m)
horizontally from or 1 foot above any door, window or gravity
air inlet into any building.
3. Install covers plate and fasten to inside wall with 4 screws.
4. Attach a seal ring (Meltalbestos SR or equivalent) to the vent
hood collar, see Figure 7. Attach Selkirk Metalbestos model
PS or model G venting to the seal ring following the venting
manufacturer’s instructions. For total safety, it is
recommended that only venting listed for use with category III
appliances (positive vent pressure, non-condensing) should
be used between the heater and the vent hood, even through
national or local codes may allow the use of type B or singlewall vent.
5. Install the remaining vent sections back to the heater, following
the venting manufacturer’s instructions on assembling and
sealing joints. Follow good venting practice regarding
properly supporting vent system and keeping the number of
offsets to a minimum. See Table 2 for the maximum allowable
number of elbows in venting system.
6. Install the flue reducer included with the exhaust hood between
the vent system and the heater.
7. Seal all vent connections and venting with sealants supplied
by vent pipe manufacturer or with a high-temperature silicone
sealant suitable for continuous temperatures of 500°F
(260°C). Acceptable sealant include Dow Corning 736
or equivalent.
8
FIGURE 6.
DIRECT VENTING - FOR BTPV MODELS
All exhaust vent terminal, flue reducer, and intake vent terminal
are supplied with any unit intended for direct venting. These
parts must be installed without alteration.
This heater is category III appliance when used in a direct vent
application. All national and local codes pertaining to the
installation of such an appliance must be followed.
Horizontal portions of the exhaust vent system must be installed
with a minimum upward slope of 1/4” (6.35 mm) per foot of
length.
Selkirk metalbestos model PS or G vent is approved for use as
exhaust venting on these models. Model PS is a double-wall
vent with a 1” (25.4 mm) air space between pipes. Model G is a
single-wall variation of model PS for use where combustible
clearance is not a concern, see Table 4.
TABLE 4.
Selkirk Metalbestos Model PS
Clearance to Combustibles
Interior 6” (152.4 mm)
Exterior 6” (152.4 mm)
8” diameter PVC or galvanized pipe is approved for use as
intake venting on these models. Class 63, 100, 125, 200, and
schedule 40 pipe may be used for PVC pipe. Intake venting
must be adequately supported to avoid unnecessary stress on
vent hood, venting, or burner.
TABLE 5.
Dimension in BTPV
Inches (mm) 540A -740A
Flue Outlet Dia. 9 (229)
Flue Reducer Dimension 9 x 8
(Supplied) (229 x 203)
Min. Exhaust Vent Dia. Inch (mm) 8 (203)
Min. Intake Vent Dia. Inch (mm) 8 (203)
Maximum Number Of 90° 4
Elbows, Intake 45° 8
Maximum Number Of 90° 4
Elbows, Exhaust 45° 8
Total Intake Vent Max. 75 (23 m)
Length, Equiv. Ft. Min. 3 (1 m)
Total Exhaust Vent Max. 75 (23 m)
Length, Equiv. Ft. Min. 6 (1.8)
Note: Barometric draft control is not used in direct vent installations
as the venting system must be sealed.
When calculating the equivalent length of a venting system each
90 elbow is equivalent to 10 feet of straight pipe. Each 45 elbow
is equivalent to 5 feet (1.5 m) of straight pipe. Do not exceed the
maximum number of elbows as shown in Table 5. In no case may
the sum of the straight pipe lengths and the equivalent lengths of
the elbows exceed the valves in Table 5.
VENT TERMINAL LOCATIONS-EXHAUST
See “Horizontal Venting” in this manual for acceptable locations
for exhaust hoods.
VENT TERMINAL LOCATIONS-INTAKE
See Table 5 limitations on venting system design for direct vent
installations.
When considering locations for the intake terminal, bear in mind
that the terminal:
9
1. Shall be located not less than 12” (304.8 mm) above grade.
DIRECT VENT SYSTEM INSTALLATION
2. Shall be located not less than 3 (.9144 m) feet horizontally
from and not less than 3 feet (.9144 m) below an exhaust vent
terminal.
3. Shall not be located directly above an exhaust terminal.
4. Shall be located 12” (304.8 mm) above the snow line in
geographical areas where snow accumulates.
5. Shall be located not less than 7 feet 2.1 m) above grade
when adjacent to a public walkway.
6. Shall not be closer than 3 feet (.9144 m) from the inside
corner of an L - shaped structure.
7. Shall be located not less than 3 feet (.9144 m) horizontally or
3 feet (.9144 m) vertically from gas line, meter, or other gas
supply entering a structure, see Figure 6.
Plan the vent system backwards from the vent hood to the heater.
1. Use the inside wall cover plate as a template to mark two
holes in the appropriate places on the wall. Cut holes
1/2” (12.7 mm) larger to facilitate easy installation of vent
hoods, see Figures 6 and 7.
BEWARE OF CONCEALED WIRING AND PIPING INSIDE WALL.
REFER TO TABLE 3 FOR THE MAXIMUM WALL THICKNESS
“B” FOR EACH MODEL.
2. Slide hoods through openings from outside. Fasten hoods
to exterior wall with anchors and screws supplied.
3. Install cover plate and fasten to inside wall with 4 screws
4. Attach a seal ring (Selkirk Metalbestos Model SR or equivalent)
to the vent hood collar, see Figure 7.
FIGURE 7B.
FIGURE 7.
10
5. Attach a properly sized length of Selkirk Metalbestos model
PS or model G venting to the exhaust vent adapter using the
inner vee bands, see Figures 7 and 7B on page 10.
6. Fill the grooves in both inner vee bands with high-temp
silicone sealant, Dow Corning 736 or equivalent.
7. Position the inner vee bands around the inner pipe flanges
and tighten the screws securing the bands.
WARNING
PRIMERS AND CEMENTS ARE EXTREMELY FLAMMABLE, AND
MUST NOT BE STORED OR USED NEAR HEAT OR OPEN FLAME.
ALLOW ADEQUATE CURING TIME BEFORE OPERATING HEATER.
DRAIN VALVE AND ACCESS PANELS
The heaters are equipped with a 3/4” NPT drain valves mounted
above and to the left of the burner.
8. Align the outer channel band with the outer pipe grooves
and tighten the screws securing the bands.
9. Repeat steps 6-8 for each successive pipe length until the
venting reaches the heater.
10. Follow the manufacturer’s instructions for proper support
and guide spacing for horizontal runs of pipe, see Table 6.
TABLE 6.
Vent Diameter S F
8” - BTPV -540A, 650A & 740A 15’ 3” 7’ 6”
S = Maximum spacing between two guides or a support
and a guide in either a vertical or horizontal direction.
F = Maximum height above a guide or support for free
standing system above a roof or parapet wall.
11. Use an expansion joint between any two fixed points in the
exhaust venting system wherever the expansion may exceed
1/4”. Selkirk Metalbestos model PS and model G venting
will expand by one inch per 100°F in gas temperature per
100 feet of vent length. The expansion can be calculated by
the following formula:
Expansion, Vent length between
= x
5
Inches two fixed points, feet 100
If the expansion calculated is greater than 1/4”, an expansion
joint must be used between the two fixed points.
An access panel is located above and to the right of the burner,
see Figure 8. This panel covers the cleanout opening in the tank
which is sealed by a gasket and cover. Another cleanout access
panel is located towards the back of the heater.
FIGURE 8.
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 9 and 9A.
Minimum required gas supply pipe size is 1 1/4”. The figures
shown are for straight lengths of pipe at 0.5 in. w.c. pressure
drop, which is considered normal for low pressure systems.
Note that fittings such as elbows and tees will add to the pipe
pressure drop.
12. Attach the flue reducer included in the exhaust vent hood
package to the flue collar on the heater.
13. Attach the flue reducer to the vent system using a seal ring.
Attach this ring to the venting using the inner vee bands as
outlined in Steps 5-7.
14. Attach 8” air-intake connector to intake vent hood collar. It
may be necessary to use a slip-slip coupling to fit the pipe
to the intake vent hood.
15. Attach 8” air-intake connector back to the 6” burner air inlet
with 8” x 6” reducer. Prime and cement each joint to assure
gas-tight construction.
16. Seal all joints at the vent hoods with silicone sealant. Also
seal the joints at the flue collar and air inlet adapter. Joint on
the exhaust side must be sealed with high-temp silicone
sealant, Dow Corning 736 or equivalent.
TABLE 9
MAXIMUM CAPACITY OF PIPE IN CUBIC FEET OF GAS PER HOUR
(Based upon a Pressure Drop of 0.5 inch Water Column
and 0.5 Specific Gravity Gas and max. gas press. of .5 psig)
LENGTH
IN Nominal Iron Pipe Sizes, Inches
FEET 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 4"
10 175 360 680 1400 2100 3960 6300 11000 23000
20 120 250 485 950 1460 2750 4360 7700 15800
30 97 200 375 770 1180 2200 3520 6250 12800
40 82 170 320 660 990 1900 3000 5300 10900
50 73 151 285 580 900 1680 2650 4750 9700
60 66 138 260 530 810 1520 2400 4300 8800
70 61 125 240 490 750 1400 2250 3900 8100
80 57 118 220 460 690 1300 2050 3700 7500
90 53 110 205 430 650 1220 1950 3450 7200
100 50 103 195 400 620 1150 1850 3250 6700
125 44 93 175 360 550 1020 1650 2950 6000
150 40 84 160 325 500 950 1500 2650 5500
175 37 77 145 300 460 850 1370 2450 5000
200 35 72 135 280 430 800 1280 2280 4600
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