DuraVent DuraStack Installation User Manual
Page 11
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.