07/03
17789 Rev H
13
NA SERIES INSTALLATION INSTRUCTIONS
WARNING!
Do not combine offsets to
create an offset greater
than 30° from vertical.
This may create a fire
hazard since the natural
draft may be restricted.
1. Using Offsets and Returns
a.
To bypass any overhead obstructions, the chimney may be offset using a 15°
or 30° offset/return. Perform the following steps to determine the correct
chimney component combination for your particular installation.
b.
An offset and return may be attached together or a chimney section(s) may be
used between an offset and return.
1)
Measure how far the chimney needs to be shifted to enable it to avoid the
overhead obstacle. See Figure 7, dimension A to determine chimney
sections required to achieve the needed shift.
2)
After determining the offset dimension, refer to Table 1 and find the A
dimension closest to
but not less than
the distance of shift needed for
your installation.
3)
The B dimension that coincides with the A dimension represents the
required vertical clearance that is needed to complete the offset and return.
4)
Read across the chart and find the number of chimney sections required
and the model number of those particular chimney parts.
5)
Whenever the chimney penetrates a floor/ceiling, a firestop spacer must
be installed.
6)
The effective height of the fireplace assembly is measured from the base
of fireplace to top of starter collar. See Figure 6.
°
5
1
°
0
3
6
0
3
L
S
/
2
1
3
L
S
2
1
3
L
S
A
N
8
1
3
L
S
4
2
3
L
S
/
6
3
3
L
S
6
3
3
L
S
A
N
/
8
4
3
L
S
8
4
3
L
S
A
N
A
B
A
B
1
5
/
8
"
3
1
3
/
8
"
3
7
/
8
"
4
1
1
/
2
"
-
-
-
-
-
-
2
7
/
8
"
7
1
3
/
4
"
6
1
/
4
"
8
1
5
/
8
"
1
-
-
-
-
-
-
-
8
5
/
8
"
"
¾
2
2
2
-
-
-
-
-
4
1
/
2
"
3
2
5
/
8
"
9
1
/
4
"
3
2
3
/
4
"
-
1
-
-
-
-
-
-
1
1
5
/
8
"
7
2
7
/
8
"
1
1
-
-
-
-
"
6
9
2
3
/
8
"
2
1
1
/
4
"
"
9
2
-
-
1
-
-
-
7
1
/
4
"
"
4
3
4
1
5
/
8
"
"
3
3
-
2
-
-
-
-
-
-
5
1
1
/
4
"
4
3
1
/
8
"
-
-
-
1
-
-
-
-
7
1
5
/
8
"
8
3
1
/
4
"
1
-
-
1
-
-
-
-
0
2
5
/
8
"
3
4
1
/
2
"
-
-
2
-
-
-
0
1
5
/
8
"
6
4
3
/
4
"
1
2
1
/
4
"
4
4
5
/
8
"
-
-
-
-
1
-
1
1
7
/
8
"
1
5
3
/
8
"
3
2
5
/
8
"
8
4
3
/
8
"
1
-
-
-
1
-
-
-
6
2
5
/
8
"
3
5
7
/
8
"
-
-
-
2
-
-
3
1
3
/
4
"
8
5
3
/
8
"
7
2
1
/
4
"
5
5
3
/
4
"
-
-
-
-
-
1
"
5
1
"
3
6
9
2
5
/
8
"
"
9
5
1
-
-
-
-
1
6
1
1
/
2
"
8
6
3
/
4
"
2
3
5
/
8
"
4
6
1
/
4
"
-
1
-
-
-
1
"
8
1
4
7
5
/
8
"
5
3
5
/
8
"
9
6
1
/
2
"
-
-
1
-
-
1
-
-
8
3
5
/
8
"
4
7
5
/
8
"
-
-
-
1
-
1
-
-
"
1
4
8
7
3
/
4
"
1
-
-
1
-
1
2
2
3
/
4
"
1
9
7
/
8
"
4
4
5
/
8
"
"
5
8
-
-
-
-
1
1
"
4
2
6
9
1
/
2
"
"
7
4
9
8
1
/
8
"
1
-
-
-
1
1
5
2
7
/
8
"
3
0
1
1
/
2
"
0
5
5
/
8
"
5
9
1
/
2
"
-
-
-
-
-
2
Example:
Your A
dimension
from
Figure 7 is 14½.
Using Table 1 the
dimension closest to,
but not less than 14½
is 14
5
/
8
using a 30°
offset/return. It is then
determined from the
table that you would
need 33 (Dimension
B) between the
offset and return. The
chimney components
that best fit your
application are two
SL312s.
Figure 7 - Chimney Offset/
Return
Table 1
Offset Chart*
* Proper assembly of air cooled chimney parts result in an overlap at chimney joints of
1¼. Effective length is built into this chart.
