Air Requirements; Water (Potable) Heating And Space Heating; Venting - A.O. Smith BT- 80 Installation & Operating Instructions Manual

Commercial gas water heater glass-lined tank-type water heater
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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
2
Btu/Hr (2203mm
/kW) of the total input of all appliances in the
enclosure, but not less than 100 square inches (645cm
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
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.
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

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.
2
).
2
/kW) of the total input of
CAUTION
WARNING
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.
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.
6
FIGURE 2.
FIGURE 3.

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