AO Smith Water Heater BTF 75 User Manual

®
MODEL BTF-75  
with Hot Surface Ignition & SmartValve  
COMMERCIAL GAS, GLASS-LINED, TANK-TYPE WATER HEATER  
SAFETY INSTALLATION OPERATION MAINTENANCE LIMITED WARRANTY  
Thank you for buying this energy efficient water heater from A.O. Smith  
Water Products Company. We appreciate your confidence in our  
products.  
CAUTION  
TEXT PRINTED OR OUTLINED IN RED CONTAINS  
INFORMATIONRELATIVETOYOURSAFETY.PLEASEREAD  
THOROUGHLY BEFORE INSTALLING AND USING THIS  
APPLIANCE.  
A DIVISION OF A.O.SMITH CORPORATION  
McBee, South Carolina U.S.A.  
Stratford, Ontario Canada  
® SmartValve is a Registered Trademark of Honeywell Inc.  
KEEP THIS MANUAL IN THE POCKET ON THE HEATER FOR FUTURE REFERENCE  
WHENEVER MAINTENANCE ADJUSTMENT OR SERVICE IS REQUIRED.  
PRINTED IN U.S.A. 0901  
PART NO. 194643-000  
ROUGH-IN-DIMENSIONS  
TOP VIEW  
*INSTALLINACCORDANCEWITHLOCALCODES  
FIGURE 1  
ALL DIMENSIONS IN INCHES  
Model Units  
BTF-75 Inches 66 5/16 58 1/2 29 5/8 25 3/8 15 3/16  
cm 168.4 148.6 75.2 64.5  
A
B
C
D
E
F
G
H
J
K
L
M
4
14  
16 1 1/4  
1
1/2 11 15/16  
30.3  
38.6 10.2 35.6 40.6 3.2  
NPT NPT  
RECOVERY CAPACITIES  
Input  
Rating  
Approx. Approx. Temp. °C  
17  
22  
28  
33  
39  
70  
44  
80  
50  
90  
56  
61  
67  
72  
78  
Model  
Rating  
Btu/Hr  
80,000  
Gal.  
Cap.  
74  
Liter  
Cap.  
284  
KW/Hr  
Rise ° F  
LPH  
30  
40  
50  
60  
100 110 120  
130  
226  
60  
140  
210  
55  
BTF-75  
23.4  
979 734 587 489 419 367 326 294 267 245  
259 194 155 129 111 97 86 78 71 65  
GPH  
Recovery capacity based on 80% thermal efficiency.  
FOREWORD  
The design of model BTF-75 complies with the latest version of where the installation is to be made. These shall be carefully followed  
ANSI Z21.10.3/CSA 4.3 M98 as automatic storage or automatic circulating in all cases. Authorities having jurisdiction should be consulted before  
tank type water heaters.  
installations are made.  
Installation diagrams are found in this manual. These diagrams will serve The installation must conform to these instructions and the local code  
to provide the installer with a reference for the materials and method of authority having jurisdiction. In the absence of local codes, the installation  
piping necessary. It is highly essential that all water and gas piping be must comply with the latest editions of the National Fuel Gas Code,  
installed as shown on the diagrams.  
ANSI Z223.1/NFPA 54. The NFPA. This is available from the Canadian  
Standards Association, 8501 East Pleasant Valley Road, Cleveland, OH  
In addition to these instructions, the equipment shall be installed in 44131, or the National Fire Protection Association, 1 Batterymarch Park,  
accordance with those installation regulations in force in the local area Quincy, MA 02269.  
2
TABLE OF CONTENTS  
PAGE  
PAGE  
ROUGH-INDIMENSIONS .............................................................. 2  
FOREWORD ...............................................................................2  
GENERALSAFETYINFORMATION  
Installation Of Sidewall Vent System ....................................... 7  
Vent Terminal Installation, Sidewall .......................................... 7  
Preparation Of Blower Assembly ......................................... 8-9  
Installation Of Vent System, Sidewall ..................................... 10  
Installation Of Vertical Vent System ....................................... 10  
Vent Pipe Preparation ......................................................... 10-12  
Gas Connections ................................................................... 12  
Connection of Gas Pipe ......................................................... 12  
OPERATION  
To Operate Heater ................................................................. 12  
Lighting & Operating Label ..................................................... 13  
Purging .................................................................................. 14  
Temperature Regulation ......................................................... 14  
MAINTENANCE  
Main Burner ........................................................................... 14  
High Temperature Cut-Off Switch .......................................... 15  
Venting System .....................................................................15  
Power Venter Maintenance ................................................... 15  
T & P Valve............................................................................ 15  
Draining ................................................................................. 15  
Main Burner And Igniter ...................................................... 15-16  
Condensation ........................................................................ 16  
Cathodic Protection - Anode ..................................................16  
Service & Repair ................................................................... 16  
TROUBLESHOOTING ............................................................. 16-19  
LIMITEDWARRANTY ................................................................. 20  
Precautions ............................................................................ 3  
Chemical Vapor Corrosion ......................................................3  
Improper Combustion .............................................................. 3  
Liquid Petroleum Models ........................................................ 3-4  
Extended Non-Use periods ..................................................... 4  
Insulation Blankets .................................................................. 4  
Circulating Pump .....................................................................4  
Dishwashing Machine Requirements ...................................... 4  
INSTALLATION  
Required Ability ...................................................................... 4  
General .................................................................................. 4  
Grounding ..............................................................................4  
High Altitude Installation .......................................................... 4  
Location Of Heater ............................................................... 4-5  
Air Requirements ....................................................................5  
Unconfined Space .................................................................. 5  
Confined Space ...................................................................... 5  
Water Connections ................................................................. 5  
Water (Potable) Heating & Space Heating ............................. 5-6  
Closed Water System ............................................................. 6  
Relief Valve ............................................................................ 6  
Venting ...................................................................................6  
Vent Pipe Termination ............................................................ 6-7  
Planning The Vent System .................................................... 7-8  
IMPROPER COMBUSTION  
GENERAL SAFETY INFORMATION  
WARNING  
PRECAUTIONS  
ATTICAND/OREXHAUSTFANSOPERATINGONTHEPREMISESWITHA  
WATERHEATERCANRESULTINCARBONMONOXIDEPOISONINGAND  
DEATH.  
DONOTUSETHISAPPLIANCEIFANYPARTHASBEENUNDERWATER.  
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.  
OPERATION OF THESE FANS CAN PRODUCE A NEGATIVE DRAFT IN  
THEAREAOFTHEWATERHEATERPREVENTINGTHEPRODUCTSOF  
COMBUSTIONFROMEXHAUSTINGTHROUGHTHEVENTPIPE.  
IFTHEUNITISEXPOSEDTOTHEFOLLOWING,DONOTOPERATEHEATER  
UNTIL ALL CORRECTIVE STEPS HAVE BEEN MADE BY A QUALIFIED  
SERVICEMAN.  
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.  
1. EXTERNALFIRE.  
2. DAMAGE.  
DONOTOBSTRUCTTHEFLOWOFCOMBUSTIONANDVENTILATING  
AIR. ADEQUATEAIRFORCOMBUSTIONANDVENTILATIONMUSTBE  
PROVIDEDFORSAFEOPERATION.  
3. FIRINGWITHOUTWATER.  
4. SOOTING.  
LIQUID PETROLEUM MODELS  
CHEMICAL VAPOR CORROSION  
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.  
WARNING  
CORROSIONOFTHEFLUEWAYSANDVENTSYSTEMMAYOCCUR IF  
AIRFORCOMBUSTIONCONTAINSCERTAINCHEMICALVAPORS. SUCH  
CORROSIONMAYRESULTINFAILUREANDRISKOFASPHYXIATION.  
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.  
Spray can propellants, cleaning solvents, refrigerator and air conditioning  
refrigerants, swimming pool chemicals, calcium 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 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).  
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 a diminishing sense of smell with age. For these  
reasons, the use of a propane gas detector is recommended.  
3
IF YOU EXPERIENCE AN OUT-OF-GAS SITUATION, DO NOT TRY TO  
RELIGHTAPPLIANCESYOURSELF. AskyourLPdeliverypersontorelight  
pilots for you. Only trained LP professionals should conduct the required  
safety checks in accordance with industry standards.  
All dishwashing machines meeting the National Sanitation Foundation  
requirements are designed to operate with water flow pressures  
between 15 and 25 psi (103Kpa and 173 Kpa). Flow pressures above  
25 psi (173Kpa), or below 15 psi (103 Kpa), will result in improperly  
sanitized dishes. Where pressures are high, a water pressure reducing  
or flow regulating control valve should be used in 1800F line to the  
dishwashing machine, and should be adjusted to deliver water between  
these limits.  
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  
PERIODOFTIME(GENERALLYTWOWEEKSORMORE). 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  
OROPENFLAMENEARTHEFAUCETATTHETIMEITISOPEN.  
The National Sanitation Foundation also recommends circulation of 1800F  
(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 1800F (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  
REQUIRED ABILITY  
INSULATION BLANKETS  
INSTALLATIONORSERVICEOFTHISWATERHEATERREQUIRESABILITY  
EQUIVALENT TO THAT OF A LICENSED TRADESMAN IN THE FIELD  
INVOLVED. PLUMBING, ELECTRICALAIRSUPPLY, VENTINGANDGAS  
SUPPLYAREREQUIRED.  
Insulation blankets available to the general public for external use on  
gas water heaters are not necessary with A.O. Smith products. The  
purpose of an insulation blanket is to reduce the standby heat loss  
encountered with storage tank heaters. Your A.O. Smith water heater  
meets and exceeds the National Appliance Energy Conservation Act  
standards with respect to insulation and standby loss requirements,  
making an insulation blanket unnecessary.  
GENERAL  
The heater is designed to operate on 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. The  
installation must conform to these instructions and the local code authority  
having jurisdiction. In the absence of local codes, conform to the latest  
edition of 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 East Pleasant Valley Road, Cleveland, OH  
44131, and both documents are available from the National Fire Protection  
Association, 1 Batterymarch Park, Quincy, MA 02269.  
WARNING  
Should you choose to apply an insulation blanket to this heater, you  
should follow these instructions. Failure to follow these instructions  
can restrict the air flow required for proper combustion, potentially  
resulting in fire, asphyxiation, serious personal injury or death.  
Do not cover the gas valve or temperature & pressure relief valve.  
Do not allow insulation to come within 2" of the air inlet box, to prevent  
blockage of the dilution air.  
Do not allow insulation to come within 2" of the floor to prevent  
blockage of combustion air flow to the burner.  
GROUNDING  
The water heater, when installed, must be grounded in accordance with  
local codes, or in the absence of local codes: The National Electric  
Code, ANSI/NFPA 70;  
Do not cover the instruction manual. Keep it on the side of the water  
heater or nearby for future reference.  
Do obtain new warning and instruction labels from A.O. Smith for  
placement on the blanket directly over the existing labels.  
HIGH ALTITUDE INSTALLATION  
Do inspect the insulation blanket frequently to make certain it does  
not sag, thereby obstructing combustion air flow.  
CAUTION  
INSTALLATIONS ABOVE 2000 FT. REQUIRE REPLACEMENT OF THE  
BURNER ORIFICE IN ACCORDANCE WITH THE NATIONAL FUEL GAS  
CODE (ANSI Z223.1/NFPA 54). FAILURE TO REPLACE THE ORIFICE  
COULDRESULTINIMPROPERANDINEFFICIENTOPERATIONOFTHE  
APPLIANCE,PRODUCINGCARBON MONOXIDEGASINEXCESSOFSAFE  
LIMITS, WHICH COULD RESULT IN SERIOUS PERSONAL INJURY OR  
DEATH. CONTACTYOURGASSUPPLIERFORANYSPECIFICCHANGES  
WHICHMAYBEREQUIREDINYOURAREA.  
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.  
A.O.SMITHBUILDSSOMEMODELSSPECIFICALLYFORHIGHALTITUDE  
SERVICE.  
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.  
PLEASECHECKTHERATINGPLATEBEFOREMAKINGCHANGES.  
LOCATION OF HEATER  
DISHWASHING MACHINE REQUIREMENT  
When installing the heater, consideration must be given to proper location.  
Location selected should be as close to the wall as practicable with  
adequate air supply and as centralized with the water piping system as  
possible.  
These appliances meet the National Sanitation Foundation Standard for  
sanitary installations when used with the following leg kits, Part No’s.  
6570-0 and 6570-7.  
4
If the confined space is within a building of tight construction, air for  
combustion, ventilation and power venter dilution must be obtained from  
outdoors. When directly communicating with the outdoors or  
communicating 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.  
The heater is design certified by the Canadian Standards for installation  
on combustible flooring in a closet having minimum clearances from  
combustible material of: 2" clearance from sides and rear, 6" from the  
front and 24" from the top. (Standard clearance.) If clearances stated  
on the heater differ from standard clearances, install water heater  
according to clearances stated on heater.  
A minimum clearance of 4" must be allowed for access to replaceable  
parts such as the thermostats, drain valve and relief valve. A top  
clearance of 24" should be allowed for blower assembly service.  
Adequate clearance for servicing this appliance should be considered  
before installation, such as changing the anodes, etc. Minimum  
clearances for proper operation are given above.  
WARNING  
In cold climates provide protection against freeze-up.  
THEHEATERSHOULDBELOCATEDINANAREAWHERELEAKAGEOF  
THETANKORCONNECTIONSWILLNOTRESULTINDAMAGETOTHE  
AREA ADJACENT TO THE HEATER OR TO LOWER FLOORS OF THE  
STRUCTURE. When such locations cannot be avoided, a suitable drain  
pan should be installed under the heater, see fig. 1. The pan must not  
restrict combustion air flow. Such pans should have a minimum length  
and width of at least 2 inches greater than the diameter of the heater  
and should be piped to an adequate drain. Drain pans suitable for these  
heaters are available from your dealer or A. O. Smith Water Products  
Company, 5621 W. 115th Street, Alsip, Illinois 60803.  
WARNING  
DO NOT INSTALL THIS WATER HEATER DIRECTLY ON A CARPETED  
FLOOR. A FIRE HAZARD MAY RESULT. Instead the water heater must  
be placed on a metal or wood panel extending beyond the full width and  
depth by at least 3 inches (76.2mm) in any direction. If the heater is  
installed in a carpeted alcove or closet, the entire floor shall be covered  
by the panel.  
AIR REQUIREMENTS  
In calculating the free area of a vent opening, the blocking effect of  
screens, louvers and grills should be considered. Screens shall not be  
of a mesh smaller than 1/4 inch square. If the free area is not known,  
the latest edition of National Fuel Gas Code ANSI Z223.1 recommends  
using figures of 20-25 percent free area for wood louvers or 60-75  
percent for metal grills or louvers.  
WATER CONNECTIONS  
UNCONFINED SPACE  
Refer to figure 12 for typical installation. A suitable pipe thread sealant  
must be used to prevent leakage.  
In buildings of conventional frame, brick or stone construction, unconfined  
spaces may provide adequate air for combustion, ventilation, and dilution  
air for power venter.  
WATER (POTABLE) HEATING AND SPACE  
HEATING  
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, ventilation, and venter  
dilution must be obtained from outdoors. The installation instructions for  
confined spaces must be followed.  
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.  
CONFINED SPACE  
3. This unit may NEVER be connected to any existing heating system or  
component(s) previously used with a non-potable water heating  
appliance.  
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 WITHIN 12 INCHES OF THE  
ENCLOSURETOPANDONEWITHIN12INCHESOFTHEENCLOSURE  
BOTTOM. Each opening shall have a free area of one square inch per  
1000 Btuh of the total input of all appliances in the enclosure, but not  
less than 100 square inches.  
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 Fig. 2 for suggested piping  
arrangement.  
5
MIXING VALVE APPLICATION FOR TWO TEMPERATURE WATER  
SINGLE TEMPERATURE  
ARNING  
RATURE SETTING SHOULD NOT EXCEED SAFE USE  
RATURE AT FIXTURES. SEE TEMPERATURE REGULATION  
ON PAGE 9. IF HIGHER PREHEAT TEMPERATURES ARE  
NECESSARY TO OBTAIN ADEQUATE BOOSTER OUTPUT, ADD AN  
ANTI-SCALD VALVE FOR HOT WATER SUPPLIED TO FIXTURES.  
CIRCULATING RETURN LINE CONNECTIONS  
TEMPERED WATER LOOP, IF USED, CONNECT TO POINT "A". STORED  
TEMPERATURE WATER LOOP, IF USED, CONNECT TO COLD WATER INLET  
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.  
FIGURE2  
CLOSED WATER SYSTEM  
VENTING  
A closed system will exist if a back-flow preventer (check valve),  
pressure reducing valve, or other similar device is installed in the cold  
water line between the water heater and the street main (or well).  
Excessive pressure may develop due to the thermal expansion of heated  
water causing premature tank failure or intermittent relief valve operation.  
This type of failure is not covered by the limited warranty. An expansion  
tank may be necessary in the cold water supply to alleviate this situation.  
Contact the local plumbing authority.  
WARNING  
THEINSTRUCTIONSINTHISSECTIONONVENTINGMUSTBEFOLLOWED  
TOAVOIDCHOKEDCOMBUSTIONORRECIRCULATIONOFFLUEGASES.  
SUCH CONDITIONS CAUSE SOOTING OR RISKS OF FIRE AND  
ASPHYXIATION.NEVEROPERATETHEHEATERUNLESSITISVENTED  
TOTHEOUTDOORSANDHASADEQUATEAIRSUPPLYTOAVOIDRISKS  
OFIMPROPEROPERATION,FIRE,EXPLOSIONORASPHYXIATION.  
VENT PIPE TERMINATION  
If the temperature and pressure relief valve on the appliance discharges  
periodically, this may be due to thermal expansion in a closed water  
supply system. Contact the water supplier or local plumbing inspector  
on how to correct situation. DO NOT PLUG THE TEMPERATURE AND  
PRESSURERELIEFVALVE.  
The first step is to determine where the vent pipe will terminate. The  
vent may terminate through the roof (see Figure 9) or through a sidewall  
(see Figure 8).  
IMPORTANT  
RELIEF VALVE  
The vent system must terminate so that proper clearances are maintained  
as cited in local codes or the latest edition of the National Fuel Gas Code,  
ANSI Z223.1, 7.3.4e and 7.8a, b.  
ANEWTEMPERATUREANDPRESSURERELIEFVALVECOMPLYINGWITH  
THESTANDARDFORRELIEFVALVESANDAUTOMATICGASSHUTOFF  
DEVICES FOR HOT WATER SUPPLY SYSTEMS, ANSI Z21.22 (LATEST  
EDITION)MUSTBEINSTALLEDINTHEHEATERINTHEMARKEDOPENING  
PROVIDED. THE VALVE MUST BE OF A SIZE (INPUT RATING) THAT  
WILLBEADEQUATEFORYOURSIZEHEATER.  
For your convenience instructions on proper installation through a  
sidewall are provide in Figure 3 and the numbered points below:  
1. The exit terminals of a mechanical vent system shall be not less than  
7 feet above grade when located adjacent to public walkways.  
Check the metal tag on the relief valve and compare it to the heater’s  
rating plate. The pressure rating of relief valve must not exceed the  
working pressure shown on the rating plate of the heater. In addition  
the hourly Btu rated temperature steam discharge capacity of the relief  
valve shall not be less than the input rating of the heater. NO VALVE IS  
TOBEPLACEDBETWEENTHERELIEFVALVEANDTANK. DONOTPLUG  
THERELIEFVALVE.  
2. A venting system shall terminate at least 3 feet above any forced air  
inlet located within 10 feet.  
3. The venting system shall terminate at least 4 feet below, 4 feet  
horizontally from or, 1 foot above any door, window or gravity air  
inlet into any building.  
The drain line connected to this valve must not contain a reducing coupling  
or other restriction and must terminate near a suitable drain to prevent  
water damage during valve operation. The discharge line shall be installed  
in a manner to allow complete drainage of both the valve and line. DO  
NOTTHREAD,PLUGORCAPTHEENDOFTHEDRAINLINE.  
4. The manufacturer also recommends that the vent system termination  
not be installed closer than 3 feet from an inside corner of an L shaped  
structure and not be less than 1 foot above grade. The vent shall  
terminate a minimum of 12'' above expected snowfall level to prevent  
blockage of vent termination.  
6