Chimney Connector Systems and Clearances from Combustible Walls for
Residential Heating Appliances
A. Minimum 3.5 in (90 mm) thick brick masonry
all framed into combustible wall with a
minimum of 12-in (305 mm) brick separation
from clay liner to combustibles. The fireclay
liner (ASTM 315, Standard Specification for
Clay Fire Linings, or equivalent) minimum 5/8
in (16 mm) wall thickness, shall run from outer
surface of brick wall to, but not beyond, the
inner surface of chimney flue liner and shall
be firmly cemented in place.
B. Solid-insulated, listed factory-built chimney
length of the same inside diameter as the
chimney connector and having 1 in (25.4 mm)
or more of insulation with a minimum 9 in (229
mm) air space between the outer wall of the
chimney length and combustibles. The inner
end of the chimney length shall be flush with
the inside of the masonry chimney flue and
shall be sealed to the flue and to the brick
masonry penetration with non-water-soluble
refractory cement. Supports shall be securely
fastened to wall surfaces on all sides.
Fasteners between supports and the chimney
length shall not penetrate the chimney liner.
C. Sheet steel chimney connector, minimum 24
gauge (.024 in./.61 mm) in thickness, with a
ventilated thimble, minimum 24 gauge (.024
in/.61 mm) in thickness, having two 1 in (25.4
mm) air channels, separated from
combustibles by a minimum of 6 in (152 mm)
of glass fiber insulation. Opening shall be
covered, and thimble supported with a sheet
steel support, minimum 24 gauge (.024 in/.61
mm) in thickness. Supports shall be securely
fastened to wall surfaces on all sides and
shall be sized to fit and hold chimney section.
Fasteners used to secure chimney section
shall not penetrate chimney flue liner.
D. Solid insulated, listed factory-built chimney
length with an inside diameter 2 in (51 mm)
larger than the chimney connector and having
1 in (25.4 mm) or more of insulation, serving
as a pass-through for a single wall sheet steel
chimney connector of minimum 24 gauge
(.024 in/.61 mm) thickness, with a minimum 2
in (51 mm) air space between the outer wall of
chimney section and combustibles. Minimum
length of chimney section shall be 12 in (305
mm) chimney section spaced 1 in (25.4 mm)
away from connector using sheet steel
support plates on both ends of chimney
section. Opening shall be covered, and
chimney section supported on both sides with
sheet steel supports securely fastened to wall surfaces of minimum 24 gauge (.024 in/.61 mm) thickness.
Fasteners used to secure chimney section shall not penetrate chimney flue liner.