Installation

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
11
Figure 18 - Offsets MHS (refer to table 7)
Figure 19 - Minimum offset
MHS
Offset *
Ø 3° 15° 30° 45°
5” n/a 1-3/8” 3-5/16” 5-5/8”
6” n/a 1-7/16” 3-7/16” 5-15/16”
8” n/a 1-1/2” 3-3/4-” 6-1/2”
10” n/a 1-9/16” 4” 7-1/16”
12” n/a 1-5/8” 4-1/4” 7-11/16”
14” n/a 1-11/16” 4-1/2” 8-1/4”
16” n/a 1-3/4” 4-13/16” 8-7/8”
18” n/a 1-7/8” 5-1/16” 9-7/16”
20” n/a 1-15/16” 5-5/16” 10”
22” n/a 2” 5-5/8” 10-5/8”
24” n/a 2-1/16” 5-7/8” 11-3/16”
26” n/a 2-1/8” 6-1/8” 11-3/4”
28” n/a 2-3/16” 6-3/8” 12-3/8”
30” n/a 2-1/4” 6-11/16” 12-15/16”
32” n/a 2-5/16” 6-15/16” 13-1/2”
34” n/a 2-3/8” 7-3/16” 14-1/8”
36” n/a 2-7/16” 7-1/2” 14-11/16”
Table 11 - Minimum offset
* See table 11
OFFSETS
1. Sloped or horizontal offsets in the vertical portion of a chimney above
the breeching should be avoided except where absolutely necessary.
2. Sloped offsets require more expansion joints and secure bracing
above and below elbows.
3. With solid fuel burning appliance, the slope must not be greater than
30° from the vertical. Appliances which are capable of burning solid
fuel or are convertible to solid fuel are limited to the same 30° slope.
4. The length of the offset is determined by strength considerations. The
maximum dimension between supports, given as the MHS dimension
in table 7, is applicable to all horizontal and sloped orientations (see
figure 18)
5. The minimum offset is accomplished with two elbows directly con-
nected to each other (see Figure 34 and table 9).
6. With frequent re-support, there is no structural or operating limit to
the length of horizontal or sloped portions of model DIS chimney,
providing the system meets the capacity, pressure drop of available
equipment.
7. The carrying capacity of supports and their structural attachments
must take into account the weight of the offset plus whatever vertical
chimney is carried by that support.
8. Height limits for supports ar tabulated in Section A of these instruc-
tions.
9. The ends of any sloped or horizontal offset must be anchored to
prevent overstressing elbows and to assure proper operation of
expansion joints.
10. The vertical sections of chimney above the offset must also be sup-
ported or anchored and guided where necessary.
11. Models DIS and DAS Roof Support (RS), Wall Support (WS), Wall
Guide (WG) may be used in a variety of ways for offset support to
achieve the structural stability of the chimney system. Preferred
methods of using model DIS and DAS supports are shown in Section
C.
12. Re-supports such as those shown in Figure 31 must be securely
anchored to walls, posts, or locally fabricated rigid framework. This
framework must be designed to assure stability of attached model DIS
supports, such as Anchor Plate (AP) supports and Wall Supports (WS).
13. Supports suspended by threaded rods or from small size angles or
straps are usually not satisfactory to resist bending moments due
to offsets.