5
Merrimack Large Insert
30004671
Be aware that a chimney originally designed for fire-
place use may perform differently when used to vent an
air-controlled appliance such as your Merrimack Large
Insert - even if the flue is less than 3 times larger than
the flue collar. For example, a chimney on an outside
wall may not heat up enough to sustain an adequate
draft. Such a flue can often be improved if it is relined to
reduce its size and/or insulated to keep it warmer.
•
A positive flue connection must be made between
the Insert and the first masonry tile or prefabri-
cated metal chimney section. A positive flue con-
nection consists of a plate that seals or replaces
the fireplace damper and a section of chimney
connector that passes through the plate into the
chimney.
•
The chimney connector must be a minimum
equivalent to a 6” (15 mm) diameter opening
and must be 4 gauge or heavier stainless steel.
Chimney Connection systems are available from a
variety of manufacturers. Your Vermont Castings dealer
can recommend a system that will best meet the re-
quirements of your particular installation.
Sealing Requirements / U.S.
•
The chimney must be sealed off from room air,
either by a plate at the damper level or by sealing
the fireplace opening.
•
Unused openings to the flue must be sealed with
masonry to the thickness of the chimney wall.
Openings sealed with pie plates or wallpaper are
a hazard. In the event of a chimney fire, flames
and smoke may be forced from the openings.
canada
In canada (caN/cSa-b365-M91, Section 5):
•
A full chimney liner meeting ULC S635, Class III
(stainless steel) must be installed from the insert
to the chimney top, and securely attached to
both. The damper may be removed to accommo-
date the liner.
•
The opening of the fireplace around the insert
must be sealed to prevent room air passing to the
fireplace cavity.
•
Existing air-circulation chambers in a fireplace
with a steel liner may not be blocked.
•
Provision must be made for removal of the insert
to clean the chimney flue.
•
The existing fireplace damper (if any) should be
locked in the open position.
•
A permanent metal warning label must be affixed
to the back of the fireplace stating the fireplace
may have been altered to accommodate the in-
sert, and may be unsafe to use as a conventional
fireplace. (A Fireplace Modification Tag is in-
cluded in the hardware bag inside the Merrimack
Large Insert.)
Minimum Fireplace Dimensions
The Merrimack Large Insert will fit many fireplaces. To
confirm that it will fit yours, measure the lintel depth,
plus the height, width, and depth of your fireplace and
hearth. Compare them to the measurements in the ac-
companying chart. If you choose to install a new hearth
over an existing fireplace hearth, be sure to take its
thickness into consideration when measuring both front
and back height of the fireplace and clearances to any
existing trims and mantels.
NoTe:
The clearance between the Merrimack Large
Insert and the mantel, top trim and side trim cannot be
reduced by installing shields.
Another requirement to consider is the clearance for
movable items such as tables, bookcases, rugs, furnish-
ings, and your woodbox. All combustible materials of
this type should be a minimum of 48” (10 mm) from
the front surface of the Merrimack Large Insert. Be sure
that family members are aware of this requirement as
well, so they too will keep objects a safe distance from
the stove.
