Heatilator NA36 Installation & Operating Instructions Manual page 16

4. Assembling Chimney Sections
Attach either a straight chimney section or an offset to
the top of the fireplace (depending on your installation
requirement). Chimney sections are locked together
by pushing downward until the top section meets the
stop bead on the lower section.
The inner flue is placed to the inside of the flue section
below it. The outer casing is placed outside the outer
casing of the chimney section below it. See Figure 10.
5. Installing Firestop Spacers
Mark and cut out an opening in the ceiling for the
firestop spacer being utilized (14½” x 14½” for an
FS338/NAFS338, 14½” x 18
14½” x 23” for an FS340). Frame the opening with the
same dimension lumber used in the ceiling joists.
Install the firestop spacer.
These firestop spacers are designed to provide the
minimum 2” air space required around the chimney.
In all situations, the firestop spacers are to be nailed
to the ceiling joists from the bottom or fireplace side,
ing or attic space. In this situation, the firestop spacer
be nailed from the top side to prevent loose in-
sulation from falling into the required 2” air space
around the chimney. See Figure 11.
16
WARNING!
/ ” for an FS339 and
3
8
when the space above is an insulated ceil-
CAUTION:
NA SERIES INSTALLATION INSTRUCTIONS
17789 Rev H 07/03