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The offset and return elbows may be attached
together, or a section or sections of chimney
may be used between, but do not exceed 20' in
total length between elbows. If sections of pipe
exceed 10' between elbows, a chimney stabi-
lizer must be used at the midpoint ( Figure 36 ).
The stabilizer support straps must be attached
under tension (in shear) to structural framing
members above. When two sets of elbows are
used, the maximum combined length of chim-
ney used between elbows cannot exceed 20'
( Figure 37 ). Example: If C
exceed 10'.
If an offset exceeds 6' in length, each chimney
joint beyond the first 6' of offset to the return
elbow, must be secured by a No. 8 x ¹⁄₂" sheet
metal screw located at the underside of the joint
( Figure 38 ).
A ¹⁄₈" diameter hole must be drilled in the
chimney joint using a ¹⁄₈" diameter drill. Hole
should be drilled in center of joint overlap
( Figure 39 ). Be sure to drill only through the
outer chimney casting. Do not puncture the
inner flue.
Maximum offset of chimney system is 30°. Two
offsets must not be assembled to form a 60°
offset. However, two sets of offset and return
elbows may be used on a single flue system,
provided the total height of the system exceeds
25'.
Return elbow support straps must be securely
attached under tension (in shear) to structural
framing members above. Do not substitute a
FTF8-30 offset elbow in place of a FTF8-E30
return elbow.
OFFSET CALCULATIONS
Step 1. Use Offset Chart to determine amount
of horizontal offset (A) and height (B) for vari-
ous chimney section assemblies.
Step 2. Use "Height of Chimney Only" column
in The Vertical Elevation Chart to determine
combinations of chimney used above return
elbow to achieve desired heights. Reference
Components Effective Height Chart in vertical
elevation chart section.
Step 3. Use Elevation Chart as job estimator
only. Add necessary firestop spacers and sta-
bilizers as required. Firestop spacers must be
used as shown in Figures 22 and 23 and
stabilizers as shown in Figure 28 .
12
= 10' then C
cannot
1
2
NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.
FTF8 VERTICAL ELEVATION CHART
Height Of
Number Of FTF8
Chimney Only
Chimney Lengths
Inches
Feet/Inches 12" 18" 36" 48"
11
0 11
1
0
17
1
5
0
1
21 ¹⁄₄
9 ¹⁄₄
1
2
0
27 ¹⁄₄
3 ¹⁄₄
2
1
1
35
2 11
0
0
47
3 11
0
0
51 ¹⁄₄
3 ¹⁄₄
4
0
1
57 ¹⁄₄
9 ¹⁄₄
4
1
0
63 ¹⁄₄
3 ¹⁄₄
5
0
1
67 ¹⁄₄
7 ¹⁄₄
5
2
0
73 ¹⁄₄
1 ¹⁄₄
6
1
1
81 ¹⁄₄
9 ¹⁄₄
6
0
0
93 ¹⁄₄
9 ¹⁄₄
7
0
0
97 ¹⁄₄
1 ¹⁄₄
8
0
1
102 ¹⁄₂
6 ¹⁄₂
8
1
0
109 ¹⁄₄
1 ¹⁄₄
9
0
1
113 ¹⁄₂
5 ¹⁄₂
9
2
0
119 ¹⁄₂
9 11 ¹⁄₂
1
1
127 ¹⁄₄
7 ¹⁄₄
10
0
0
137 ¹⁄₂
5 ¹⁄₂
11
1
0
139 ¹⁄₄
7 ¹⁄₄
11
0
0
143 ¹⁄₂
11 11 ¹⁄₂
0
1
149 ¹⁄₂
5 ¹⁄₂
12
1
0
155 ¹⁄₂
12 11 ¹⁄₂
0
1
159 ³⁄₄
3 ³⁄₄
13
2
0
165 ³⁄₄
9 ³⁄₄
13
1
1
173 ¹⁄₂
5 ¹⁄₂
14
0
0
183 ³⁄₄
3 ³⁄₄
15
1
0
185 ¹⁄₂
5 ¹⁄₂
15
0
0
189 ³⁄₄
9 ³⁄₄
15
0
1
195 ³⁄₄
3 ³⁄₄
16
1
0
201 ³⁄₄
9 ³⁄₄
16
0
1
206
17
2
2
0
212
17
8
1
1
219 ³⁄₄
3 ³⁄₄
18
0
0
230
19
2
1
0
231 ³⁄₄
3 ³⁄₄
19
0
0
236
19
8
0
1
242
20
2
1
0
248
20
8
0
1
252
21
0
2
0
258
21
6
1
1
266
22
2
0
0
276
23
0
1
0
278
23
2
0
0
282
23
6
0
1
288
24
0
1
0
294 ³⁄₄
6 ³⁄₄
24
0
1
298 ¹⁄₄
24 10 ¹⁄₄
2
0
304 ¹⁄₄
4 ¹⁄₄
25
1
1
312
26
0
0
0
322 ¹⁄₄
26 10 ¹⁄₄
1
0
324
27
0
0
0
328 ¹⁄₄
4 ¹⁄₄
27
0
1
334 ¹⁄₄
27 10 ¹⁄₄
1
0
340 ¹⁄₄
4 ¹⁄₄
28
0
1
344 ¹⁄₂
8 ¹⁄₂
28
2
0
350 ¹⁄₂
2 ¹⁄₂
29
1
1
358 ¹⁄₄
29 10 ¹⁄₄
0
0
368 ¹⁄₂
8 ¹⁄₂
30
1
0
370 ¹⁄₄
30 10 ¹⁄₄
0
0
374 ¹⁄₂
2 ¹⁄₂
31
0
1
380 ¹⁄₂
8 ¹⁄₂
31
1
0
Height Of
Chimney Only
Inches
Feet/Inches 12" 18" 36" 48"
386 ¹⁄₂
2 ¹⁄₂
32
0
0
390 ³⁄₄
6 ³⁄₄
0
0
32
396 ³⁄₄
0 ³⁄₄
0
0
33
404 ¹⁄₂
8 ¹⁄₂
33
0
0
414 ³⁄₄
6 ³⁄₄
1
0
34
416 ¹⁄₂
8 ¹⁄₂
0
1
34
420 ³⁄₄
0 ³⁄₄
1
0
35
426 ³⁄₄
6 ³⁄₄
0
1
35
432 ³⁄₄
0 ³⁄₄
36
0
1
0
1
437
36
5
0
1
443
36 11
450 ³⁄₄
6 ³⁄₄
37
1
1
0
2
461
38
5
462 ³⁄₄
6 ³⁄₄
38
1
1
466 ³⁄₄
38 10 ³⁄₄
0
2
³⁄₄ 39 4³⁄₄
0
2
472
478 ³⁄₄
39 10 ³⁄₄
0
2
0
2
483
40
3
1
2
489
40
9
496 ³⁄₄
4 ³⁄₄
41
1
2
0
3
507
42
3
508 ³⁄₄
4 ³⁄₄
42
1
2
0
3
513
42
9
0
3
519
43
3
525
43
9
0
3
529 ¹⁄₄
1 ¹⁄₄
0
3
44
535 ¹⁄₄
7 ¹⁄₄
1
3
44
543
45
3
1
3
553 ¹⁄₄
1 ¹⁄₄
0
4
46
555
46
3
1
3
559 ¹⁄₄
7 ¹⁄₄
0
4
46
565 ¹⁄₄
1 ¹⁄₄
0
4
47
571 ¹⁄₄
5 ¹⁄₄
47
0
4
575 ¹⁄₂
47 11 ¹⁄₂
0
4
581 ¹⁄₂
5 ¹⁄₂
1
4
48
589 ¹⁄₄
1 ¹⁄₄
49
1
4
599 ¹⁄₂
49 11 ¹⁄₂
0
5
601 ¹⁄₄
1 ¹⁄₄
50
1
4
605 ¹⁄₂
5 ¹⁄₂
0
5
50
611 ¹⁄₂
51 11 ¹⁄₂
0
5
617 ¹⁄₂
5 ¹⁄₂
51
0
5
621 ¹⁄₂
9 ¹⁄₂
0
5
51
627 ¹⁄₂
3 ¹⁄₂
1
5
52
635 ¹⁄₂
52 11 ¹⁄₂
1
5
645 ¹⁄₂
9 ¹⁄₂
0
6
53
647 ¹⁄₂
53 11 ¹⁄₂
1
5
651 ¹⁄₂
3 ¹⁄₂
0
6
54
657 ¹⁄₂
9 ¹⁄₂
0
6
54
663 ¹⁄₂
3 ¹⁄₂
55
0
6
667 ³⁄₄
7 ³⁄₄
0
6
55
673 ³⁄₄
1 ³⁄₄
1
6
56
681 ¹⁄₂
9 ¹⁄₂
56
1
6
691 ³⁄₄
7 ³⁄₄
0
7
57
693 ¹⁄₂
9 ¹⁄₂
57
1
6
697 ³⁄₄
1 ³⁄₄
0
7
58
703 ³⁄₄
7 ³⁄₄
0
7
58
709 ³⁄₄
1 ³⁄₄
59
0
7
0
7
714
59
6
1
7
720
60
0
727 ³⁄₄
7 ³⁄₄
60
1
7
0
8
738
61
6
739 ³⁄₄
7 ³⁄₄
61
1
7
0
8
744
62
0
Number Of FTF8
Chimney Lengths
0
1
0
8
2
0
0
8
1
1
0
8
0
0
1
8
1
0
1
8
0
0
0
9
0
1
1
8
1
0
0
9
0
1
0
9
2
0
0
9
1
1
0
9
0
0
1
9
1
0
1
9
0
0
0
10
0
1
1
9
1
0
0
10
0
1
0
10
2
0
0
10
1
1
0
10
0
0
1
10
1
0
1
10
0
0
0
11
0
1
1
10
1
0
0
11
0
1
0
11
2
0
0
11
1
1
0
11
0
0
1
11
1
0
1
11
0
0
0
12
0
1
1
11
1
0
0
12
0
1
0
12
2
0
0
12
1
1
0
12
0
0
1
12
1
0
1
12
0
0
0
13
0
1
1
12
1
0
0
13
0
1
0
13
2
0
0
13
1
1
0
13
0
0
1
13
1
0
1
13
0
0
0
14
0
1
1
13
1
0
0
14
0
1
0
14
2
0
0
14
1
1
0
14
0
0
1
14
1
0
1
14
0
0
0
15
0
1
1
14
1
0
0
15
0
1
0
15
2
0
0
15
1
1
0
15
0
0
1
15
1
0
1
15
0
0
0
16
0
1
1
15
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