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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 " (305mm) OF THE ENCLOSURE TOP AND ONE IN
OR WITHIN 12" (305mm) OF THE ENCLOSURE BOTTOM.  Each
opening shall have a free area of at least one square inch per 1000
Btu/Hr (2203mm

2

/kW) of the total input of all appliances in the

enclosure, but not less than 100 square inches (645cm

2

).

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 or
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 Btu/Hr (551mm

2

/kW) 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 Btu/Hr (1102mm

2

/kW) of the total input of all appliances

in the enclosure.

WATER (POTABLE) HEATING AND SPACE

HEATING

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, see Figure 4.

  

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 (or well).

Excessive pressure may develop in such closed systems,
causing premature tank failure or intermittent relief valve
operation.  This is not a warranty failure.  An expansion tank or
a similar device is 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.

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.

Heater must be protected from freezing downdrafts.

Remove all soot or other obstructions from the chimney that will
retard a free draft.

Type B venting is recommended with these heaters.

This water heater must be vented in compliance with all local codes,
the current edition of the National Fuel Gas Code ANSI-Z223.1 or
the Natural Gas and Propane Installation Code CAN/CSA-B149.1.

If any part of the vent system is exposed to ambient temperatures
below 35° F (2° C) it must be insulated to prevent condensation.

• Do not connect the heater to a common vent or chimney with any

oil-fired or solid fuel burning equipment. This practice is prohibited
by many local  building codes as is the practice of venting gas
fired equipment to the duct work of ventilation systems.

FIGURE 2.

DRAFT HOOD

The draft hood furnished with this heater must be installed without
alteration.  Provision must be made if it is installed in confined space
or a small room to accommodate draft hood spillage and avoid risks
described in previous steps.  The upper air opening called for in the
AIR REQUIREMENTS section of this manual is for this purpose.

Locate the 3 brackets and 6 screws in the installation instruction bag.
Secure each bracket to the draft hood leg with the screws furnished.
Place the draft hood on the water heater so that legs of the draft hood
fit into the slots on the jacket top, see Figure 3.  Once the draft hood
(with brackets attached) is in place, drill a small pilot hole through
bracket hole into the jacket top.  

WARNING, DO NOT PENETRATE

THE JACKET TOP BY MORE THAN 1/4".

  Secure the brackets to

the jacket top with the screws furnished, see Figure 3.

FIGURE 3.

Summary of Contents for BT- 80

Page 1: ...er INSTALLATION OPERATION SERVICE 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 produc...

Page 2: ...ional Fuel Gas Code ANSI Z223 1 NFPA 54 or the Natural Gas and Propane Installation Code CAN CSA B149 1 These documents are available from the Canadian Standards Association 8501 East Pleasant Valley...

Page 3: ...12 Check Venting 12 13 High Temperature Limit Switch 13 SERVICE INFORMATION 13 14 Pilot and Main Burner 13 Checking Gas Input 13 14 Vent System 14 Relief Valve 14 Hot Water Odor 14 Anode Rod Inspectio...

Page 4: ...ly 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 m...

Page 5: ...tu Hr 16 7 kW CANADIAN REQUIREMENTS Appliances with inputs up to and including 400 000 BTU 117 1 kwh must be factory equipped with orifices for operation at specific elevations Standard sea level orif...

Page 6: ...ain or well Excessive pressure may develop in such closed systems causing premature tank failure or intermittent relief valve operation This is not a warranty failure An expansion tank or a similar de...

Page 7: ...VE AND TANK Your local code authority may have other specific relief valve requirements A DRAIN LINE MUST BE CONNECTED TO THE RELIEF VALVE TO DIRECT DISCHARGE TO A SAFE LOCATION TO AVOID SCALDING OR W...

Page 8: ...0 556 878 1552 3192 15 21 44 83 170 264 492 776 1391 2840 18 19 40 76 155 237 445 703 1259 2577 21 18 37 70 143 220 410 659 1142 2372 24 17 35 64 135 202 381 600 1083 2196 27 16 32 60 126 190 357 571...

Page 9: ...VALVE IS INSTALLED IN THE RELIEF VALVE OPENING OF THE HEATER DO NOT ATTEMPT TO OPERATE HEATER WITH COLD WATER INLET VALVE CLOSED TO OPERATE THE WATER HEATER 1 Close the heater drain valve by turning...

Page 10: ...10...

Page 11: ...ghtly and turn clockwise to OFF Figure A NOTE Gas control knob CANNOT be turned from PILOT to OFF unless it is pushed down slightly Do not force 4 Remove the inner and outer burner doors located below...

Page 12: ...and windows and all doors between the space in which the water heater s connected to the venting system are located and other spaces of the building Turn on all appliances not connected to the venting...

Page 13: ...PETENT SERVICE PERSON USERS OF THIS APPLIANCE SHOULD BE AWARE THAT GAS COMPONENTS WEAR OUT OVER A PERIOD OF TIME THE GAS CARRYING COMPONENTS OF THIS APPLIANCE SHOULD BE INSPECTED FOR PROPER OPERATION...

Page 14: ...PPLIANCE HOT WATER ODOR On occasion hot water may develop a strong odor If this occurs drain the heater completely flush thoroughly and refill If the problem persists chlorination of the heater and re...

Page 15: ...e obtained from your dealer distributor or the A O Smith Product Service Division Order part no 4763 1 gal packed 4 gallons per case or part no 4813 5 gallon container Hydrochloric base acids are not...

Page 16: ...t UN LIME remain in the heater for 5 minutes and then lower the container to the Drain Position see Figure 9 9 Deliming activity is indicated by foaming on the surface of the UN LIME If there is delim...

Page 17: ...ssures or temperatures in the system or to a faulty relief valve Your dealer or a qualified service technician should be called to determine the cause of the problem and to correct it 4 If you cannot...

Page 18: ...xpansion is also installed at the heater s and operational at all times The relief valve installed on the heater is not an acceptable method 4 SERVICE AND REPAIR EXPENSES Under the limited warranty th...

Page 19: ...19...

Page 20: ...20 A O SMITH WATER PRODUCTS COMPANY 500 Tennessee Waltz Parkway Ashland City TN 37015 PHONE 1 800 527 1953 www aosmithwaterheaters com E MAIL parts hotwater com...

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