Hearth and Home Technologies BIR42-B - Manual (Page 26)

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Table 8.2
B. Using 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.
• Measure the shift needed to avoid the overhead obstruction. Refer to dimension A in Figure 8.3.
• Find the appropriate A dimension listed in Table 8.2.
• The B dimension coinciding with the A dimension measurement in Table 8.2 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.
A
B
1-1/4 in. (32 mm)
OVERLAP
Figure 8.3 Chimney Offset/Return
Heatilator • Birmingham BIR42-B • 4059-681C • 9/12
A B
SL1106 SL1112 SL1118 SL1136 SL1148 in. mm in. mm
4 7/8 124 17 7/8 454 - - - - -
7 1/4 184 22 559 1 - - - -
9 3/4 248 26 1/8 664 2 - - - -
10 1/4 260 27 1/4 692 - 1 - - -
12 3/4 324 31 3/8 797 1 1 - - -
13 1/4 337 32 3/8 822 - - 1 - -
15 3/4 400 36 5/8 930 - 2 - - -
18 1/8 460 40 3/4 1035 1 2 - - -
18 3/4 476 41 3/4 1060 - 1 1 - -
21 3/4 552 47 1194 - - 2 - -
22 1/4 565 4 8 1219 - - - 1 -
24 3/4 629 52 1/8 1324 1 - - 1 -
27 3/4 705 57 3/8 1457 - 1 - 1 -
28 1/4 718 58 3/8 1483 - - - - 1
30 3/4 781 62 1/2 1588 1 - - - 1
33 3/4 857 67 3/4 1721 - 1 - - 1
36 3/4 933 73 1854 - - 1 - 1
39 3/4 1010 78 1/8 1984 - - - 2 -
41 1/8 1045 82 3/8 2092 1 - - 2 -
45 3/4 1162 88 1/2 2248 - - - 1 1
48 1/8 1222 92 3/4 2356 1 - - 1 1
51 3/4 1314 98 7/8 2511 - - - - 2
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.
Example:
Your “A” dimension from Figure 8.3 is 14 1/2 in. (368
mm). Using Table 8.2 the dimension closest to, but not
less than 14 1/2 in. (368 mm) is 15 3/4 in. (400 mm) using
a 30° offset/return.
You determined from the table that you would need
36 5/8 in. (930 mm) (Dimension “B”) between the offset
and return.
The chimney component that best fits your application is
two SL1112s.