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14
E
XTERIOR
MASONRY
C
HIMNEYS
- C
ATEGORY
I F
URNACES
O
NLY
Next, use a flashlight and small mirror to sight up the liner. B
vent must be supported so as to not come into direct contact
with the chimney walls or tile liner. If it is not, it can probably be
rehung so as to be acceptable. A thimble or fire stop may be
helpful here.
Flexible liners should be hung straight or nearly straight. If it is
spiraled in the chimney and in good condition, it should be
rehung. To do this, break the top seal; pull up and cut off the
excess liner length, and refit the top seal. Use caution when
doing this, as the cut edges of flexible liners may be sharp.
The surfaces of the liner must be physically sound. If gaps or
holes are present, the metal liner must be removed and re-
placed (Fix 4). Finally, confirm that the metal liner is the cor-
rect size for the appliances to be installed. Use the GAMA
tables and rules.
If a metal liner is not present, a clay tile liner must be present,
or the chimney must be lined (Fix 4).
Use a flashlight and small mirror at the cleanout or vent con-
nector to inspect the clay tile liner. If any of the following prob-
lems are present:
• Tile sections misaligned
• Tile sections missing
• Gaps between tile sections
• Signs of condensate drainage at the cleanout or vent
connectors
• Mortar protruding from between tile sections
• Use of sewer pipe or drainage pipe rather than an
approved fire clay tile reline the chimney (Fix 4).
Next, measure the size of the liner. It may be possible to do
this from the cleanout. The liner must be at least as large as
the minimum size established by the tables in National Fuel
Gas Code NFPA 54/ANSI Z223.1 - latest edition and in the
National Standard of Canada, CAN/CSA B149.1 and CAN/CSA
B149.2 - latest editions and amendments. If the liner is too
small or too large, then the chimney must be relined (Fix 4).
CHECK 6 - DILUTION A IR.
If gas-fired appliances are to be vented into a clay tile liner, a
source of dilution air is required.
Dilution air cannot be obtained through:
• Induced draft appliances
• Natural draft appliances with vent dampers
Sufficient dilution air can ordinarily be obtained through the draft
hood of a natural draft appliance only if the appliance’s vent
connector does not include a vent damper. If dilution air will not
be available, the chimney must be relined (Fix 4).
Liquid fuel appliances include oil furnaces, oil-fired boilers and
oil-fired water heaters.
Appliances which burn propane (sometimes referred to as LP
(liquefied petroleum)) gas are considered gas-fired appliances.
CHECK 3 - CHIMNEY C ROWN C ONDITION.
Damage from condensate usually shows up first in the crown.
If any of the following trouble signs are present, the condition of
the crown is not satisfactory:
a) Crown leaning
b) Bricks missing
c) Mortar missing
d) Tile liner cracked
e) No tile liner
f) Salt staining at mortar joints. (White stains, and mortar
becomes sandy and/or erodes.)
For problems a, b, or c, see Fix 3. If problems d, e, or f are
present, see Fix 4. IMPORTANT: It may be necessary to follow
both Fix 3 and Fix 4.
CHECK 4 - DEBRIS IN C LEANOUT
A cleanout (dropleg) must be present such that the upper edge
of the cleanout cover is at least 12 inches below the lower edge
of the lowest chimney inlet opening.
A chimney without a cleanout could become partially blocked
by debris. If no cleanout is present, the chimney must be re-
lined (Fix 4). Remove the cleanout cover, and examine the
cleanout for debris. If significant amounts of any of the following
are found:
• Fuel oil residue
• Bricks
• Mortar or sand
• Pieces of the tile liner
• Rusted pieces of the metallic liner - reline the chimney
(Fix 4).
CHECK 5 - LINER C ONDITION.
If a metal liner is present, it must be checked. It cannot be
assumed that all existing metal liners are correctly installed
and in good condition.
Remove the lowest existing vent connector, and examine the
inside of the elbow or tee at the base of the liner. A small amount
of soot may be considered acceptable, provided the installer
vacuums it away. If rusted pieces of the liner have collected
here, the metal liner must be removed and replaced (Fix 4).
Next, gently tap the inside of the liner with a Phillips screw-
driver. If the screwdriver perforates the liner, or if the tapping
does not sound like metal hitting metal, the liner must be re-
moved and replaced (Fix 4).
Remember that all appliances must be vented inside the liner.
Venting one appliance inside the liner and another appliance
outside the liner is not acceptable.