Heatilator ST42A Installation Manual page 14

G. Outside Air Kit
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inlet hood.
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inlet hood.
Installation
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outside air inlet hood.
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enclosed spaces such as an attic or garage.
NO
NO
Outlet blocked by
snow, leaves, etc.
YES
Clear area
outside
house or in
ventilated
• Use UL181 Class 1 or Class 0 rigid or flexible ducting.
crawl space
• Install with short run and add a P-trap which will help
prevent flow of cold air.
• Secure flex duct with screws or wire ties.
Figure 3.8 Outside Air Installation

+RPH 7HFK-
Garage or
NO
combustible
liquids storage Attic space
NO
Factory-built
fireplace
Heatilator • ST42A Installation Manual • 4012-051 • Rev O • 02/22
• DO NOT place outside air inlet hood close to exhaust
vents or chimneys. Fumes or odor could be drawn into
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• Locate outside air inlet hood to prevent blockage from
leaves, snow/ice, or other debris. Blockages could cause
combustion air starvation.
CAUTION! Risk of Cuts/Abrasions.
gloves and safety glasses during installation. Sheet metal
edges are sharp.
3 ft min. from
top of uppermost
chimney section
to air inlet.
Figure 3.9
Outlet placed
higher than 3 ft
below the
termination cap
Figure 3.10 Outside Air Installation with Cold Air Trap
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Outside Air Inlet Locations
Wear protective
Typical Outside Air
Installation
Recommend
around 24 inches
for a minimum bend