Specifications

7
Problem Description Can Occur when.. Possible Solutions
Oversized replace opening Generally speaking, there
should be a 1:10
relationship in the
cross-sectional area
between ue size and
replace opening. A 24”x
36” replace opening equals
864 sq.in., so the
cross-sectional area of the
ue should be at least 86
sq.in. This is equivalent to a
10” ID ue.
• The replace has been
redesigned to add more
front area.
• The replace is not
designed properly to begin
with.
• Reduce the opening by
installing a steel shield
at the top of the replace
opening. The height can
be determined by using
the 1:10 rule. Example: the
replace opening is 40”x25”
or 1,000 sq.in and the ue
size is 10” ID – or 86 sq.in.
Reduce the replace
opening to 860 sq.in. by
blocking off 140 sq.in on
top. 140 divided by 40
equals 3.5” which should be
the height of the shield.
• Reduce the opening by
rebuilding it.
• If the lintel is less than 6”
below the damper
assembly, it should be
extended. Or, add a shield
as described above.
• Install a mechanical draft
system.
The lintel may be too small
or too deep
The lintel prevents the
smoke from rolling out by
capturing and
containing it – it serves the
same purpose as the front
edge of a kitchen hood. If it
is too deep or too small, it
may not be able to capture
and contain the smoke.
• The replace is not
designed properly to begin
with.
• Increase the height of the
lintel.
• Decrease the depth of the
lintel.
• Install a mechanical draft
system.
The smoke chamber is
improperly designed
The smoke chamber guides
the smoke towards the
chimney ue. If there is no
smoke chamber, or it’s too
low, the smoke stays in the
throat or the rebox and
becomes turbulent after
which it will start spilling.
The smoke chamber should
be centered with the sides
angled at not less than 45°.
It could also be that the
inside construction is
irregular with protrusions.
• The replace is not
designed properly to begin
with.
• Increase the height of the
smoke chamber.
• Parge the smoke chamber
walls or otherwise smooth
the sides.
• Install a mechanical draft
system.
2.1.2 Problems associated with the heating appliance
The chimney is not the only culprit. The heating ap-
pliance itself can be the problem and cause spillage
or improper combustion. Heating appliance problems
depend on the appliance type. Fireplaces and stoves
experience different problems: