Harman Oakwood - Page 18

~ ~ ~ - - ~- ~- ~ - ~- ~~ ~ ~
VENTING i
~~ ~ ~
Existing Masonry Chimneys
If you plan on using a pre-existing masonry chim-
ney, have it thoroughly inspected and cleaned. Any faults
which make the chimney unsafe and unusable must be
. repaired prior to use. These can include improper height,
structural defects, blockages, inadequate clearance to
combustibles, unsealed openings into other rooms
of the
. house, signs of creosote or smoke leakage, a loose or
absent clean-out door, or absence
of a liner.
Do not connect to any air distribution
duct or system
Venting to a Masonry Chimney
When connecting to a masonry chimney, several
provisions are standard. First, whether the chimney con-
nector is vented to the chimney through a thimble or a
breech pipe, neither must pass beyond the inner surface
of the chimney liner, and both must be firmly cemented in
place with refractory cement. (A thimble is a masonry
pipe which is inserted through the
chimney wall, and is
frequently the preferred method; a breech pipe is
a piece
of steel pipe used the same way.) In Canada, a breech
pipe has ridges or protrusions to lock
it firmly into the
refractory cement.
In either case, the chimney connec-
tor vents to the chimney through the thimble or breech
pipe.
Using a thimble, the connector slides completely
inside the masonry to the inner edge
of the flue liner, and
may be easily removed for chimney and connector in-
spection. A breech pipe must extend at least
2" (50 nun)
into the room, so the connector can be attached with
sheetmetal screws.
Venting to a Masonry Fireplace Chimney
In some situations, a code compliant chimney
originally used for a masonry fireplace may be used to
install your Oakwood. In addition to the requirements
found in the previous paragraphs,
it is important to be
aware that all clearances must be met, including those
from the chimney connector to combustibles
-18" (360
mm)to sides and 18" (450 nun) to ceiling. Do not forget
to include floor protection in your plans. (See Clearances
and Floor Protection
in this section.) Since many fire-
places have exposed wooden mantels and trim, pay spe-
cial attention to the clearances necessary to these mate-
rials.
If your fireplace chimney is behind a combustible
wall, you must use an approved wall pass-through sys-
tem to gain access to the masonry chimney. The chim-
ney connector must enter the chimney at a place where
it is lined, and the fireplace must be made inoperable.
18 Harman Oakwood
Mechanical
fasteners
(minimum of
fhree) but not at
bottom of
connector
Chimney
connector
~:~~~ri~:ttothe
inSide ofthe
chimney
liner
High-temperature sealant used
to cement the clay thimble
CONNECTION TO A MASONRY CHIMNEY
USING
A CLAY THIMBLE
For example, you might remove the damper, replacing it
with a secure, airtight, noncombustible seal (removable
for inspection); this also satisfies the requirement that no
room air must be allowed to enter the chimney.
Installing to a Prefabricated Chimney
When venting your Oakwood using a prefabri-
cated chimney, be sure to contact local building code au-
thorities, and to follow the manufacturer's instructions
ex-
actly. Use only the manufacturer's parts; do not use
makeshift installation techniques. All prefabricated chim-
neys must
betested to either the U.S. or Canadian high-
temperature standards, UL 103 or ULC-629.