Hearthstone
Clydesdale Fireplace Insert Model 8491
Page 18 of 35
A 6” diameter flue provides adequate draft and
performance. You can use an 8" (203 mm) diameter
existing flue with a reducer. An oversized flue
contributes to creosote accumulation. (In this case,
bigger is NOT better.)
There are two ways to install a prefabricated metal
chimney:
An
interior
installation where the chimney passes
inside the residence through the ceiling and roof.
An
exterior
installation where the chimney passes
through the wall behind the Fireplace Insert then
up the outside of the residence.
Whenever possible, choose an interior chimney. An
interior chimney heats quickly and retains its heat;
thus promotes a better draft and discourages the
formation of creosote. An exterior chimney does not
benefit from the surrounding warmth of the building,
so it typically operates at lower flue temperatures
than an interior chimney. An exterior chimney’s draft
is not as strong and may experience increased
creosote accumulation.
REMOVE THE DAMPER OR LOCK IT OPEN.
Connection to a Masonry Chimney
Before connecting to a masonry chimney, hire a
professional to examine the chimney for cracks,
loose mortar, and other signs of deterioration and
blockage. If the chimney needs repair, complete
them before installing and using your Fireplace
Insert. Do not install your Fireplace Insert until the
chimney is safe for use.
Ensure the chimney’s cleanout is complete and
working properly. To avoid a loss of draft, the
cleanout must close off completely. If allowed to
cool, your Fireplace Insert will perform poorly and
creosote will build up in the chimney.
Ensure the size of the chimney’s flue is appropriate
for this Fireplace Insert and that it is not too large.
Use a masonry chimney with an 8" x 8" (203 mm x
203 mm) tile size for best results. An oversized flue
will contribute to the accumulation of creosote.
Use the following checklist to ensure that your
masonry chimney meets these minimum
requirements:
Chimney wall construction:
Brick or modular block at least 4" (102 mm) thick.
A rubble or stone wall.
Flue liner:
Minimum ceramic flue liner thickness of 5/8" (16
mm).
Installed with refractory mortar.
At least 1" (25 mm) air space.
An equivalent flue liner must be a listed chimney
liner system meeting type HT requirements or
other approved material.
Interior chimney requirements:
At least 2" (51 mm) clearance to combustible
structure
Fire stops must be installed at the spaces where
the chimney passes through floors and/or ceiling.
Insulation must be 2" (51 mm) from the chimney.
Exterior chimney requirements:
At least 1" (25 mm) clearance to combustible
structure.
Chimney height requirements: (See Figures 8 &
9)
At least 3 feet (0.9 m) higher than the highest
part of the roof opening through which it passes.
At least 2 feet (0.6 m) higher than any part of the
roof within 10 feet (3 m) measured horizontally
from the top of the chimney. This Fireplace
Insert requires a minimum chimney height of 13
feet (4 m). The maximum allowable chimney
height is 30 feet (9m).
The damper area around the chimney liner must
be sealed, or the surround must be sealed to the
fireplace front, to prevent room air from entering
the chimney cavity of the fireplace.
WARNING: DO NOT REMOVE BRICKS OR
MORTAR FROM THE EXISTING FIREPLACE!
(Exception)
Masonry or steel (including the damper
plate) may be removed from the smoke shelf and
adjacent damper frame if necessary to accommodate
a chimney liner, provided their removal will not
weaken the structure of the fireplace and chimney,
and will not reduce protection for clearance to
combustible materials to less then required by the
National Building Code.
