A.O. Smith BTX-80 SERIES 100 Water Heater User Manual


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14
Figure 7. The water heater shall have clearances of at least 1 inch
(25mm)fromthesidesandbackand6inches(150mm)fromthe
front of the appliance. The opening shall directly communicate with
the outdoors or shall communicate through a vertical or horizontal duct
to the outdoors or spaces that freely communicate with the outdoors
and shall have a minimum free area of the following:
1. 1squareinchper3000Btu/hr(700mm
2
perkW)ofthetotalinput
rating of all appliances located in the enclosure, and
2. Not less than the sum of the areas of all vent connectors in space.
OUTDOOR AIR THROUGH TWO HORIZONTAL DUCTS
FIGURE 8.
Confined space shall be provided with two permanent horizontal
ducts,onecommencingwithin12inches(300mm)oftopandone
commencingwithin12inches(300mm)ofbottomofenclosure.Horizontal
ducts shall communicate directly with outdoors. See Figure 8.
Each duct opening shall have a minimum free area of 1 square inch
per2,000Btu/hr(1100mm
2
perkW)oftheaggregateinputratingofall
appliances installed in the enclosure.
When ducts are used, they shall be of the same cross sectional area
as the free area of the openings to which they connect. The minimum
dimension of rectangular air ducts shall be not less than 3 inches.
OUTDOOR AIR THROUGH TWO VERTICAL DUCTS
The illustrations shown in this section of the manual are a reference for
theopeningsthatprovidefreshairintoconnedspacesonly.
Do not refer to these illustrations for the purpose of vent installation.
See Installation of Vent System on pages 19-26 for complete venting
installation instructions.
FIGURE 9.
Theconnedspaceshallbeprovidedwithtwopermanentvertical
ducts,onecommencingwithin12inches(300mm)ofthetopand
onecommencingwithin12inches(300mm)ofthebottomofthe
enclosure. The vertical ducts shall communicate directly with the
outdoors. See Figure 9.
Each duct opening shall have a minimum free area of 1 square inch
per4,000Btu/hr(550mm
2
perkW)oftheaggregateinputratingof
all appliances installed in the enclosure.
When ducts are used, they shall be of the same cross sectional
area as the free area of the openings to which they connect. The
minimum dimension of rectangular air ducts shall be not less than
3 inches.
AIR FROM OTHER INDOOR SPACES
FIGURE 9A.
Theconnedspaceshallbeprovidedwithtwopermanentopenings,
onecommencingwithin12inches(300mm)ofthetopandone
commencingwithin12inches(300 mm) ofthebottomofthe
enclosure. See Figure 9A.
Eachopeningshallcommunicatedirectlywithanadditionalroom(s)
ofsufcientvolumesothatthecombinedvolumeofallspacesmeets
thecriteriaforanUnconnedSpace.
Each opening shall have a minimum free area of 1 square inch per
1,000Btu/hr(1100mm
2
perkW)oftheaggregateinputratingofall
appliances installed in the enclosure. Each opening shall not be less
than100squareinches(645cm
2
).
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