Offsets/Returns - Heatilator BIR42-B Installation Manual

B. Offsets/Returns
• Use an offset/return to bypass overhead obstructions.
• An offset and return can be used as a single entity or separated by chimney section(s).
WARNING! Risk of Fire! DO NOT use offset/returns greater than 30°. Chimney draft will be restricted and could cause
overheating and fire. Secure offsets with screws ( not to exceed 1/2" / 13 mm in length) Secure returns with strapping.
Straight chimney sections may be secured with screws. Keep chimney sections from separating or twisting.
• Measure the shift needed to avoid the overhead obstruction. Refer to dimension A in Figure 4.2.
• Find the appropriate A dimension listed in Table 4.3. The B dimension coinciding with the A dimension measurement in
Table 4.3 represents the required vertical clearance needed to complete the offset/return.
• Read across the chart to find the number of chimney sections/model numbers needed between the offset and return.
Figure 4.2 Chimney Offset/Return
Table 4.3 Offset Dimensions
A B
in. mm in.
4 7/8 124 17 7/8
7 1/4 184 22
9 3/4 248 26 1/8
10 1/4 260 27 1/4
12 3/4 324 31 3/8
13 1/4 337 32 3/8
15 3/4 400 36 5/8
18 1/8 460 40 3/4
18 3/4 476 41 3/4
21 3/4 552 47
22 1/4 565 48
24 3/4 629 52 1/8
27 3/4 705 57 3/8
28 1/4 718 58 3/8
30 3/4 781 62 1/2
33 3/4 857 67 3/4
36 3/4 933 73
39 3/4 1010 78 1/8
41 1/8 1045 82 3/8
45 3/4 1162 88 1/2
48 1/8 1222 92 3/4
51 3/4 1314 98 7/8
Proper assembly of air cooled chimney parts results in an overlap of chimney joints
of 1-1/4 in. (32 mm). Effective length is built into this table.
A
B
1-1/4 in. (32 mm)
OVERLAP
SL1106 SL1112 SL1118 SL1136 SL1148
mm
454 - -
559 1 -
664 2 -
692 - 1
797 1 1
822 - -
930 - 2
1035 1 2
1060 - 1
1194 - -
1219 - -
1324 1 -
1457 - 1
1483 - -
1588 1 -
1721 - 1
1854 - -
1984 - -
2092 1 -
2248 - -
2356 1 -
2511 - -
Heatilator • Birmingham 36-B Installation Manual • 4059-709 • Rev AB • 06/23
Example:
Your "A" dimension from Figure 4.2 is 14-1/2 in. (368
mm). Using Table 4.3 the dimension closest to, but not
less than 14-1/2 in. (368 mm) is 15-3/4 in. (400 mm) us-
ing a 30° offset/return.
You determine from the table that you need 36-5/8 in.
(930 mm) (Dimension "B") between the offset and return.
The chimney components that best fits your application
are two SL1112's.
- - -
- - -
- - -
- - -
- - -
1 - -
- - -
- - -
1 - -
2 - -
- 1 -
- 1 -
- 1 -
- - 1
- - 1
- - 1
1 - 1
- 2 -
- 2 -
- 1 1
- 1 1
- - 2
17