1- Sloped offsets require more expansion joints and secure bracing above and below
elbows.
2- The length of the offset is determined by strength considerations. The maximum
dimension between supports is given in
Table 5 and Figure 36b
, and is applicable
to all horizontal and sloped orientations
3- The minimum offset is accomplished with two elbows directly connected to each
other (see
Figure 36
and
Table 8a, b, c, d, e.
).
4- With frequent re-support, there is no structural or operating limit to the length of
horizontal or sloped portions of Models DCL, DIS PRO and DAS PRO, providing the
system meets the capacity, pressure drop of available equipment.
5- The carrying capacity of supports and their structural attachments must take into
account the weight of the offset plus whatever vertical sections are carried by that
support.
6- Height limits for supports are tabulated in SUPPORT METHODS AND HEIGHT LIMITS
of these instructions.
7- The ends of any sloped or horizontal offset must be anchored to prevent overstressing
elbows and to assure proper operation of expansion joints.
8- The vertical sections above the offset must also be supported or anchored and
guided where necessary.
9- Models DCL, DIS PRO and DAS PRO Heavy Duty Floor Guide (
FGHD
), Heavy Duty
Wall Support (
WSHD
) and Heavy Duty Wall Guide (
WGHD
) may be used in a variety
of ways for offset support to achieve the structural stability of the system. Preferred
methods of using Models DCL, DIS PRO and DAS PRO supports are shown in SUPPORTS
section.
10- Re-supports such as those shown in
Figure 56 and 57
must be securely anchored to
walls, posts, or locally fabricated rigid framework. This framework must be designed
to assure stability of attached Models DCL, DIS PRO and DAS PRO supports, such
as Anchor Plate (
AP
) supports and Heavy Duty Wall Supports (
WSHD
).
11- Supports suspended by threaded rods or from small size angles or straps are usually
not satisfactory to resist bending moments due to offsets.
12- There is no limit on the angle or slope of an offset for gas or liquid fuel burning
appliances, but with a solid fuel burning appliance the slope must not be greater
than 30° from the vertical. Chimneys for combination fuel heating appliances which
are capable of burning solid fuel or are convertible to solid fuel are limited to the
same 30° slope even if the current choice of fuel is gas or oil.
Elbows are not designed to take bending loads or thermal expansion. Thus, Elbows
must be structurally supported or protected from thermal expansion. Structural parts
such as posts or beams may also be needed to hold chimney supports in position. See
ELBOW SUPPORT
section.
OFFSETS
Diameter
Ø (in.)
3°
15°
30°
45°
90°
5
3/8
2
4 1/8
6 1/4
13 1/4
6
3/8
2
4 1/4
6 5/8
14 1/4
7
3/8
2
4 3/8
6 7/8
15 1/4
8
3/8
2
4 1/2
7 1/8
16 1/4
9
3/8
2 1/8
4 5/8
7 1/2
17 1/4
10
3/8
2 1/8
4 3/4
7 3/4
18 1/4
11
3/8
2 1/8
4 7/8
8
19 1/4
12
3/8
2 1/8
5
8 3/8
20 1/4
13
3/8
2 1/4
5 1/8
8 5/8
21 1/4
14
3/8
2 1/4
5 1/4
8 7/8
22 1/4
16
3/8
2 3/8
5 1/2
9 1/2
24 1/4
18
3/8
2 3/8
5 3/4
10 1/8
26 1/4
20
3/8
2 1/2
6 1/8
10 5/8
28 1/4
22
3/8
2 1/2
6 3/8
11 1/4
30 1/4
24
3/8
2 5/8
6 5/8
11 7/8
32 1/4
26
3/8
2 5/8
6 7/8
12 1/2
34 1/4
28
3/8
2 3/4
7 1/8
13
36 1/4
30
3/8
2 3/4
7 3/8
13 5/8
38 1/4
32
3/8
2 7/8
7 5/8
14 1/8
40 1/4
34
3/8
3
8
14 3/4
42 1/4
36
3/8
3
8 1/4
15 3/8
44 1/4
TABLE 8a - Minimum (2) Elbow Offsets - DCL
Dimensions are in inches
18
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Figure 35a: 3
°
Elbow
Removable
Alignment
Sleeve
Figure 35b: 15
°
Elbow
Figure 35c: 30 Elbow
Removable
Alignment
Sleeve
Figure 35e: 90° Elbow
ELBOWS
ELBOWS (E3, E15, E30, E45,E90)
Elbows are used for changes of direction in horizontal or vertical portions of a system. All
elbows feature the standard joint assembly as described in
JOINT ASSEMBLY
section. Elbows
are used in combination to make different angles ranging from 3° to 90° in horizontal and
vertical segments. See
Figure 35a, b, c, d, e
for all kind of Elbows.
Figure35d: 45Elbow
Figure 36a - Offset of
two elbows
Figure 36b - Maximum Spacing
between supports for Offset
