Service Manual

PRODUCT DESIGN
25
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
replaced (Fix 4).
Finally, confirm that the metal liner is the correct 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
connector to inspect the clay tile liner. If any of the following
problems 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 ap-
proved 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/CGA B149.1 and CAN/
CGA 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 Air.
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 re-
lined (Fix 4).
Check 7 - Complete the Installation.
If Checks 1 through 6 have been satisfactory, and the liner
is an acceptable size as determined by the tables in Na-
tional Fuel Gas Code NFPA 54/ANSI Z223.1 - latest edition
and in the National Standard of Canada, CAN/CGA B149.1
and CAN/CGA B149.2 - latest editions and amendments,
then the clay tile liner can probably be used as a vent for the
gas appliances. However, the installer must keep in mind
the following factors which may render the tile liner unsuit-
able for use as a vent:
• Extremely cold weather
• Long vent connectors
• Masonry chimneys with no air gap between the liner
and the bricks. (In practice, this can be difficult to
detect.)
• Exterior chimneys (The tables in National Fuel Gas
Code NFPA 54/ANSI Z223.1 - latest edition and in
the National Standard of Canada, CAN/CGA B149.1
and CAN/CGA B149.2 - latest editions and amend-
ments assume interior chimneys.)
If, in the judgment of the local gas utility, installer, and/or
local codes; one or more of the above factors is likely to
present a problem, the chimney must be relined (Fix 4).
Fix 1 - Liner Termination.
Any cap or roof assembly used with a liner must be ap-
proved by the liner manufacturer for such use. The liner and
cap/roof assembly must then terminate above the roof in
accordance with the manufacturer’s instructions.
In some cases, a shorter extension above the roof may be
possible with a liner than would be required with a masonry
chimney.
For further information on relining, see Fix 4.
Fix 2 - Change Venting Arrangements
If the masonry chimney has more than one channel, it may
be possible to vent the gas appliances into one channel and
vent the solid or liquid fuel appliance(s) into another
channel(s). Do not vent an 80% furnace inside of a metal
liner with other appliances vented outside the liner.
Alternatively, the homeowner may agree to discontinue use
of the fireplace (solid fuel appliance). If so, the tile liner must
be cleaned to remove creosote buildup. The fireplace open-
ing must then be permanently sealed.
If oil-fired appliance(s) are being replaced by gas-fired
appliance(s), the tile liner must first be cleaned to remove
the fuel oil residue.
If none of the above options are practical, the 80% furnace
may need to be vented vertically with B vent.
Under some conditions a 90%+ furnace could be installed
rather than an 80%. The 90% furnace can be vented hori-
zontally or vertically through PVC pipe.
Fix 3 - Rebuild the Crown.
If the chimney crown is damaged, a qualified mason must
repair it in accordance with nationally recognized building
codes or standards. One such standard which may be refer-
enced is the Standard for Chimneys, Fireplaces, Vents, and
Solid Fuel Burning Appliances, ANSI/NFPA 211.
Fix 4 - Relining.
Relining options include B vent and flexible liners.
If the chimney has diagonal offsets, B vent probably cannot
be used.