Page 16
1) Maintain the 40mm
clearances (air
spaces) to
combustibles when
passing through
ceilings, walls, roofs,
enclosures, attic
rafter, or other
nearby combustible
surfaces. Do not
pack air spaces
with insulation.
2) Set the gas
appliance in its
desired location.
Drop a plumb bob down from the
ceiling to the position of the
appliance flue exit, and mark the
location where the flue will
penetrate the ceiling. Drill a small
hole at this point. Next, drop a
plumb bob from the roof to the hole
previously drilled in the ceiling, and
mark the spot where the flue will
penetrate the roof.
4) Assemble the desired lengths of
pipe and elbows. Ensure that all
pipes and elbow connections are
fully sealed.
5) Cut a hole in the roof centered on
the small drilled hole placed in the
roof in Step 2. The hole should be
of sufficient size to meet the
minimum requirements for
clearance to combustibles of
40mm. Slip the flashing under the
shingles (shingles should overlap
half the flashing) as per Dia. 3.
6) Continue to assemble pipe lengths.
Note: If an offset is necessary in the
attic to avoid obstructions, it is
important to support the flue pipe
every 900mm, to avoid excessive
stress on the elbows, and
possible separation. Wall straps
are available for this purpose.
Galvanized pipe is desirable above
the roofline due to its higher corrosion
resistance. Continue to add pipe
sections through the flashing until
the height of the flue cap meets the
minimum height requirements
specified in Dia. 4 or local codes.
Note that for steep roof pitches, the
vertical height must be increased. A
poor draft, or down drafting can
result from high wind conditions near
big trees or adjoining roof lines, in
these cases, increasing the flue
height may solve the problem.
7) Ensure flue is vertical and secure
the base of the flashing to the roof
with roofing rails, slide storm collar
over the pipe section and seal with
a mastic.
Note: Apply sealant "Mill-Pac" to inner
pipe and high temperature
silicone sealant to outer pipe on
every joint.
VERTICAL TERMINATION
Dia. 1
Roof Pitch Minimum Flue Height
Feet Meters
flat to 7/12 2 0.61
over 7/12 to 8/12 2 0.61
over 8/12 to 9/12 2 0.61
over 9/12 to 10/12 2.5 0.76
over 10/12 to 11/12 3.25 0.99
over 11/12 to 12/12 4 1.22
over 12/12 to 14/12 5 1.52
over 14/12 to 16/12 6 1.83
over 16/12 to 18/12 7 2.13
over 18/12 to 20/12 7.5 2.29
over 20/12 to 21/12 8 2.44
Dia. 4
8) Install the vertical termination cap.
Note: Any closets or storage spaces, which the
flue passes through must be enclosed.
Follow the current AG 601 and NZS
5262 standards.
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