15
F
IX
3 - R
EBUILD
THE
C
ROWN
If the chimney crown is damaged, a qualified mason must re-
pair it in accordance with nationally recognized building codes
or standards. One such standard which may be referenced is
the Standard for Chimneys, Fireplaces, Vents, and Solid Fuel
Burning Appliances, ANSI/NFPA 211.
F
IX
4 - R
ELINING
Relining options include B vent and flexible liners.
If the chimney has diagonal offsets, B vent probably cannot be
used.
If B vent is to be used, it must be supported adequately. Sup-
ports (such as fire stops or thimbles) must be used to prevent
the B vent from coming into direct contact with the tile liner or
chimney walls. Direct contact would result in higher heat loss,
with an increased possibility of poor venting system perfor-
mance.
It is not acceptable to vent one appliance inside the B vent and
other appliances outside. The excess space between the B
vent and the chimney walls must be covered at the top of the
chimney by a weatherproof, corrosion resistant flashing.
The B vent should then be topped with a listed vent cap. The
listed vent cap will, when installed per the manufacturer’s in-
structions, prevent problems due to rain, birds, or wind effects.
A B-vent installed as described in this section is considered to
be an enclosed vent system, and the sizing 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 may be used.
If a flexible liner is to be used, it must be made of the proper
materials:
•
For most residential applications, an aluminum liner
should be acceptable.
•
If the combustion air supplied to the furnace will be
contaminated with compounds containing chlorine or
fluorine, a liner of AL 29-4C stainless steel should be
used. Common sources of chlorine and fluorine
compounds include indoor swimming pools and
chlorine bleaches, paint strippers, adhesives, paints,
varnishes, sealers, waxes (which are not yet dried)
and solvents used during construction and remodeling.
Various commercial and industrial processes may also
be sources of chlorine/fluorine compounds.
•
Heavier gauge 300 and 400 series stainless steel liners
were developed for use with oil or solid fuel appliances.
They are not suitable for use with gas-fired appliances.
Flexible liners specifically intended and tested for gas
applications are listed in the UL “Gas and Oil
Equipment Directory”. (UL Standard 1777).
For sizing of flexible liners, see Note 22 and the tables in the
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.
To install the liner, read and follow the liner manufacturer’s in-
structions and your local codes. Excess liner length should be
pulled out of the chimney and cut off. Use caution when doing
this, as the cut edges of flexible liners may be sharp. Do not
spiral excess liner inside of the chimney. Support the liner as
recommended by the liner manufacturer.
Some manufacturers of flexible liners offer an insulation sleeve
designed to be added to the liner before it is installed in the
chimney. (Poured insulation, either vermiculite or other materi-
als, is no longer recommended.) Insulation will need to be added
to the flexible liner if:
•
It is required by the liner manufacturer’s instructions.
•
The previous liner was properly sized and installed,
and suffered from condensation damage.
•
It is required by your local building codes.
Even if none of those three conditions exist which require addi-
tional liner insulation, the installer may wish to consider it if:
•
The local climate is very cold.
•
The chimney is very tall.
•
The vent connectors used are very long or have a large
number of elbows.
•
Local experience indicates that flexible liners installed
without insulation are likely to have condensation
problems.
Insulation must be selected and installed in accordance with
the liner manufacturer’s instructions.
Finally, cap the chimney and terminate the liner in accordance
with the liner manufacturer’s instructions.
E
LECTRICAL
C
ONNECTIONS
HIGH
VOLTAGE
!
T
O
AVOID
THE
RISK
OF
ELECTRICAL
SHOCK
,
WIRING
TO
THE
UNIT
MUST
BE
POLARIZED
AND
GROUNDED
.
WARNING
HIGH
VOLTAGE
!
T
O
AVOID
PERSONAL
INJURY
OR
DEATH
DUE
TO
ELECTRICAL
SHOCK
,
DISCONNECT
ELECTRICAL
POWER
BEFORE
SERVICING
OR
CHANGING
ANY
ELECTRICAL
WIRING
.
WARNING
L
ABEL
ALL
WIRES
PRIOR
TO
DISCONNECTION
WHEN
SERVICING
CONTROLS
.
W
IRING
ERRORS
CAN
CAUSE
IMPROPER
AND
DANGEROUS
OPERATION
.
V
ERIFY
PROPER
OPERATION
AFTER
SERVICING
.
CAUTION
