Heatilator MH36A Operating Instructions Manual page 12

1. Using Offsets and Returns
a. To bypass any overhead obstructions, the chimney may be offset using a 15-deg (SL315) or 30-deg (SL330)
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)
2)
3)
4)
5)
6)
Do not combine offsets to create an offset greater than 30 deg from vertical. This may create a fire hazard since
the natural draft may be restricted.
Offset/Returns
A
1-5/8 in. 13-3/8 in. 3-7/8 in. 14-1/2 in.
2-7/8 in. 17-3/4 in. 6-1/4 in. 18-5/8 in.
4-1/8 in. 22-3/8 in. 8-5/8 in. 22-3/4 in.
4-1/2 in. 23-5/8 in. 9-1/4 in. 23-3/4 in.
5-3/4 in. 28-1/4 in. 11-5/8 in. 27-7/8 in.
6 in.
7-1/4 in.
7-3/4 in. 36-1/8 in. 15-1/4 in. 34-1/8 in.
8-3/4 in. 39-3/4 in. 17-5/8 in. 38-1/4 in.
Proper assembly of air cooled chimney parts results in an overlap at chimney joints of 1-1/4 in. Effective
length is built into this table.
12
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.
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.
The "B" dimension that coincides with the "A" dimension represents the required vertical clearance that is
needed to complete the offset and return.
Read across the chart and find the number of chimney sections required and the model number of those
particular chimney parts.
Whenever the chimney penetrates a floor/ceiling, a firestop spacer must be installed.
The effective height of the fireplace assembly is measured from the base of fireplace to top of starter collar.
See Figure 6.
Figure 7 - Chimney Offset/
Return
Table 1
15° 30°
B A B
29-3/8 in. 12-1/4 in. 29 in.
34 in. 14-5/8 in. 33 in.
MH SERIES INSTALLATION INSTRUCTIONS
WARNING!
Offset Chart
SL306 SL312 SL318 SL324 SL336 SL348
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1 - -
2 - -
- 1 -
1 1 -
- - 1
- 2 -
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1 - -
17804 Rev i
Example:
Your
dimension from Figure 7 is
14-1/2 in. Using Table 1 the
dimension closest to, but not
less than 14-1/2 in.
14-5/8 in. using a 30-deg
offset/return. It is then
determined from the table that
you would need 33 in.
(Dimension "B") between the
offset and return. The chimney
components that best fit your
application are two SL312s.
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- - -
- - -
- - -
- - -
- - -
- - -
1 - -
1 - -
"A"
is
08/04