Heatilator BIR42 Owner's Manual page 22

3 ft min. from
top of uppermost
chimney section
to air inlet.
NO
Outlet blocked by
snow, leaves, etc.
YES
Clear area
outside
house or in
ventilated
Use only duct materials specified by manufacturer (preferably
crawl space
with short run or mainly straight duct, except small dip for cold
air trap which will help prevent flow of cold air).
Outside air installed
side not shown)
NO
Garage or
NO
combustible
Attic space
liquids storage
Factory-built
fireplace
NO
Outlet placed
higher than 3 ft
below the
termination cap