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Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
D. Frame the Fireplace
NOTICE:
Hearth extension design must be determined
before installation of fireplace.
If the fireplace is placed on the floor the maximum height
of a finished raised hearth is 7 1/2 in. (192 mm), if you
want a higher raised hearth the fireplace must be placed
on a platform.
WARNING! Risk of Fire!
You must comply with all
minimum air space clearances to combustibles.
DO NOT
pack required air spaces with insulation or other materi-
als.
WARNING! Risk of Fire!
Comply with all minimum clear-
ances specified.
• A minimum 1/2 in. (13 mm) air clearance must be
maintained at the back and sides of the fireplace
assembly.
• Chimney sections at any level require a 2 in. (51 mm)
minimum air space clearance between the framing and
chimney section.
Figure 3.5 shows a typical framing (using 2 x 4 lumber)
of the fireplace, assuming combustible materials are
used. All required clearances to combustibles around the
fireplace must be adhered to. See Figure 3.2. Any framing
across the top of the fireplace must be above the level of
the top standoffs. (No recess above standoffs.)
The finished cavity depth must be no less than 27 in.
(686 mm). Framing must extend straight up all the way to
the ceiling.
CAUTION!
Risk of Cuts/Abrasions. Wear protective gloves
and safety glasses during installation. Sheet metal edges
are sharp.
WARNING! Risk of Fire!
Prevent contact with sagging,
loose insulation.
•
DO NOT install against vapor barriers or exposed
insulation.
• Secure insulation and vapor barriers.
• Provide minimum air space clearances at the sides and
back of the fireplace assembly.
E. Secure and Level the Fireplace
This fireplace may be placed on either a combustible
or noncombustible continuous flat surface. Follow the
instructions for framing in Section 3. Slide the fireplace
into position. Be sure to provide the minimum 1/2 in. air
clearance at the sides and back of the fireplace.
The fireplace should be positioned so the face of the non-
combustible material on the fireplace will be flush with the
face of the drywall on the walls.
Level the fireplace and shim as necessary.
You must maintain
2 in. (51 mm) min. air space
clearance from the
chimney to the
enclosure.
27 in.
(686 mm)
Note:
Fireplace
Header cannot be
positioned until after
the fireplace assembly
is in place.
12 in. (305 mm) max.
48 in.
(1219 mm)
Figure 3.5 Framing the Fireplace
1/2 in.
(13 mm)
Fireplace must be set out
1/2 in. (13 mm) in front of
the face of the framing
material.
