Lennox Hearth MERIT PLUS MP-36OD - Manual (Page 16)

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE. 16
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 stabilizer
must be used at the midpoint (Figure 45). 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
chimney used between elbows cannot exceed
20' (Figure 46). Example: If C
1
= 10' then C
2
cannot exceed 10'.
If an offset exceeds 6' in length, each chimney
joint beyond the fi rst 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 47).
A 1/8" diameter hole must be drilled in the
chimney joint using a 1/8 " diameter drill. The
hole should be drilled in center of joint overlap
(Figure 48). Be sure to drill only through the
outer chimney casting. Do not puncture the
inner fl ue.
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 fl ue
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 the Offset Chart (Table 4) to deter-
mine amount of horizontal offset (A) and height
(B) for various 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 fi restop spacers and stabilizers
as required. Firestop spacers must be used as
shown in Figures 31 & 32 and stabilizers as
shown in Figure 37.
FTF8 Vertical Elevation Chart
11" to 380 1/2"
Inches Feet/Inches 12" 18" 36" 48"
11 0 11 1 0 0 0
17 1 5 0 1 0 0
21 ¹⁄₄ 1 9 ¹⁄₄ 2 0 0 0
27 ¹⁄₄ 2 3 ¹⁄₄ 1 1 0 0
35 2 11 0 0 1 0
47 3 11 0 0 0 1
51 ¹⁄₄ 4 3 ¹⁄₄ 0 1 1 0
57 ¹⁄₄ 4 9 ¹⁄₄ 1 0 0 1
63 ¹⁄₄ 5 3 ¹⁄₄ 0 1 0 1
67 ¹⁄₄ 5 7 ¹⁄₄ 2 0 0 1
73 ¹⁄₄ 6 1 ¹⁄₄ 1 1 0 1
81 ¹⁄₄ 6 9 ¹⁄₄ 0 0 1 1
93 ¹⁄₄ 7 9 ¹⁄₄ 0 0 0 2
97 ¹⁄₄ 8 1 ¹⁄₄ 0 1 1 1
102 ¹⁄₂ 8 6 ¹⁄₂ 1 0 0 2
109 ¹⁄₄ 9 1 ¹⁄₄ 0 1 0 2
113 ¹⁄₂ 9 5 ¹⁄₂ 2 0 0 2
119 ¹⁄₂ 9 11 ¹⁄₂ 1 1 0 2
127 ¹⁄₄ 10 7 ¹⁄₄ 0 0 1 2
137 ¹⁄₂ 11 5 ¹⁄₂ 1 0 1 2
139 ¹⁄₄ 11 7 ¹⁄₄ 0 0 0 3
143 ¹⁄₂ 11 11 ¹⁄₂ 0 1 1 2
149 ¹⁄₂ 12 5 ¹⁄₂ 1 0 0 3
155 ¹⁄₂ 12 11 ¹⁄₂ 0 1 0 3
159 ³⁄₄ 13 3 ³⁄₄ 2 0 0 3
165 ³⁄₄ 13 9 ³⁄₄ 1 1 0 3
173 ¹⁄₂ 14 5 ¹⁄₂ 0 0 1 3
183 ³⁄₄ 15 3 ³⁄₄ 1 0 1 3
185 ¹⁄₂ 15 5 ¹⁄₂ 0 0 0 4
189 ³⁄₄ 15 9 ³⁄₄ 0 1 1 3
195 ³⁄₄ 16 3 ³⁄₄ 1 0 0 4
201 ³⁄₄ 16 9 ³⁄₄ 0 1 0 4
206 17 2 2 0 0 4
212 17 8 1 1 0 4
219 ³⁄₄ 18 3 ³⁄₄ 0 0 1 4
230 19 2 1 0 1 4
231 ³⁄₄ 19 3 ³⁄₄ 0 0 0 5
236 19 8 0 1 1 4
242 20 2 1 0 0 5
248 20 8 0 1 0 5
252 21 0 2 0 0 5
258 21 6 1 1 0 5
266 22 2 0 0 1 5
276 23 0 1 0 1 5
278 23 2 0 0 0 6
282 23 6 0 1 1 5
288 24 0 1 0 0 6
294 ³⁄₄ 24 6 ³⁄₄ 0 1 0 6
298 ¹⁄₄ 24 10 ¹⁄₄ 2 0 0 6
304 ¹⁄₄ 25 4 ¹⁄₄ 1 1 0 6
312 26 0 0 0 1 6
322 ¹⁄₄ 26 10 ¹⁄₄ 1 0 1 6
324 27 0 0 0 0 7
328 ¹⁄₄ 27 4 ¹⁄₄ 0 1 1 6
334 ¹⁄₄ 27 10 ¹⁄₄ 1 0 0 7
340 ¹⁄₄ 28 4 ¹⁄₄ 0 1 0 7
344 ¹⁄₂ 28 8 ¹⁄₂ 2 0 0 7
350 ¹⁄₂ 29 2 ¹⁄₂ 1 1 0 7
358 ¹⁄₄ 29 10 ¹⁄₄ 0 0 1 7
368 ¹⁄₂ 30 8 ¹⁄₂ 1 0 1 7
370 ¹⁄₄ 30 10 ¹⁄₄ 0 0 0 8
374 ¹⁄₂ 31 2 ¹⁄₂ 0 1 1 7
380 ¹⁄₂ 31 8 ¹⁄₂ 1 0 0 8
Table 3a
Inches Feet/Inches 12" 18" 36" 48"
386 ¹⁄₂ 32 2 ¹⁄₂ 0 1 0 8
390 ³⁄₄ 32 6 ³⁄₄ 2 0 0 8
396 ³⁄₄ 33 0 ³⁄₄ 1 1 0 8
404 ¹⁄₂ 33 8 ¹⁄₂ 0 0 1 8
414 ³⁄₄ 34 6 ³⁄₄ 1 0 1 8
416 ¹⁄₂ 34 8 ¹⁄₂ 0 0 0 9
420 ³⁄₄ 35 0 ³⁄₄ 0 1 1 8
426 ³⁄₄ 35 6 ³⁄₄ 1 0 0 9
432 ³⁄₄ 36 0 ³⁄₄ 0 1 0 9
437 36 5 2 0 0 9
443 36 11 1 1 0 9
450 ³⁄₄ 37 6 ³⁄₄ 0 0 1 9
461 38 5 1 0 1 9
462 ³⁄₄ 38 6 ³⁄₄ 0 0 0 10
466 ³⁄₄ 38 10 ³⁄₄ 0 1 1 9
472 ³⁄₄ 39 4³⁄₄ 1 0 0 10
478 ³⁄₄ 39 10 ³⁄₄ 0 1 0 10
483 40 3 2 0 0 10
489 40 9 1 1 0 10
496 ³⁄₄ 41 4 ³⁄₄ 0 0 1 10
507 42 3 1 0 1 10
508 ³⁄₄ 42 4 ³⁄₄ 0 0 0 11
513 42 9 0 1 1 10
519 43 3 1 0 0 11
525 43 9 0 1 0 11
529 ¹⁄₄ 44 1 ¹⁄₄ 2 0 0 11
535 ¹⁄₄ 44 7 ¹⁄₄ 1 1 0 11
543 45 3 0 0 1 11
553 ¹⁄₄ 46 1 ¹⁄₄ 1 0 1 11
555 46 3 0 0 0 12
559 ¹⁄₄ 46 7 ¹⁄₄ 0 1 1 11
565 ¹⁄₄ 47 1 ¹⁄₄ 1 0 0 12
571 ¹⁄₄ 47 5 ¹⁄₄ 0 1 0 12
575 ¹⁄₂ 47 11 ¹⁄₂ 2 0 0 12
581 ¹⁄₂ 48 5 ¹⁄₂ 1 1 0 12
589 ¹⁄₄ 49 1 ¹⁄₄ 0 0 1 12
599 ¹⁄₂ 49 11 ¹⁄₂ 1 0 1 12
601 ¹⁄₄ 50 1 ¹⁄₄ 0 0 0 13
605 ¹⁄₂ 50 5 ¹⁄₂ 0 1 1 12
611 ¹⁄₂ 51 11 ¹⁄₂ 1 0 0 13
617 ¹⁄₂ 51 5 ¹⁄₂ 0 1 0 13
621 ¹⁄₂ 51 9 ¹⁄₂ 2 0 0 13
627 ¹⁄₂ 52 3 ¹⁄₂ 1 1 0 13
635 ¹⁄₂ 52 11 ¹⁄₂ 0 0 1 13
645 ¹⁄₂ 53 9 ¹⁄₂ 1 0 1 13
647 ¹⁄₂ 53 11 ¹⁄₂ 0 0 0 14
651 ¹⁄₂ 54 3 ¹⁄₂ 0 1 1 13
657 ¹⁄₂ 54 9 ¹⁄₂ 1 0 0 14
663 ¹⁄₂ 55 3 ¹⁄₂ 0 1 0 14
667 ³⁄₄ 55 7 ³⁄₄ 2 0 0 14
673 ³⁄₄ 56 1 ³⁄₄ 1 1 0 14
681 ¹⁄₂ 56 9 ¹⁄₂ 0 0 1 14
691 ³⁄₄ 57 7 ³⁄₄ 1 0 1 14
693 ¹⁄₂ 57 9 ¹⁄₂ 0 0 0 15
697 ³⁄₄ 58 1 ³⁄₄ 0 1 1 14
703 ³⁄₄ 58 7 ³⁄₄ 1 0 0 15
709 ³⁄₄ 59 1 ³⁄₄ 0 1 0 15
714 59 6 2 0 0 15
720 60 0 1 1 0 15
727 ³⁄₄ 60 7 ³⁄₄ 0 0 1 15
738 61 6 1 0 1 15
739 ³⁄₄ 61 7 ³⁄₄ 0 0 0 16
744 62 0 0 1 1 15
FTF8 Vertical Elevation Chart
386 1/2" to 744"
Table 3b