Heat & Glo VRT-BZ-N-AUB Owner's Manual page 35

Step 3.
To install the round support box/wall thimble cover in a flat
ceiling, cut a 229 mm square hole in the ceiling, centered
on the hole drilled in Step 2. Frame the hole as shown in
Figure 7.22.
FRAMING
229 mm x 229 mm
Figure 7.22
Step 4.
Assemble the desired lengths of pipe and elbows necessary
to reach from the gas stove up through the round support
box. Ensure that all pipe and elbow connections are in their
fully twist-locked position. Assemble as instructed.
Step 5.
Cut a hole in the roof centered on the small drill hole
placed in the roof in Step 2. The hole should be of sufficient
size to meet the minimum requirements for clearance to
combustibles, as specified. Continue to assemble lengths of
pipe and elbows necessary to reach from the ceiling support
box/wall thimble up through the roof line. Galvanized pipe
and elbows may be utilized in the attic, as well as above
the roofline. The galvanized finish is desirable above the
roofline, due to its higher corrosion resistance (compared
to black pipe).
NOTE:
(1
) If an offset is necessary in the attic to avoid obstructions,
it is important to support the flue pipe every 91.4cm to
avoid excessive stress on the elbows, and possible
separation. Wall straps are available for this purpose,
Figure 7.10, page 15.
(2) Whenever possible, use 45° elbows, instead of 90°
elbows. The 45° elbow offers less restriction to the flow
of flue gases and intake air.
Step 6.
Slip the flashing over the pipe section(s) protruding through
the roof. Secure the base of the flashing to the roof with
roofing nails. Ensure the roofing material overlaps the top
edge of the flashing as shown in Figure 7.23. Verify that
the chimney is the required height above the roof. See roof
pitch table, Figure 4.3.
35
CEILING JOISTS
ROUND CEILING
SUPPORT BOX/WALL
THIMBLE COVER
40 mm LONG
WOOD SCREWS
Heat & Glo • VRT-AUB • 2123-980_R14 • 12/14
SHINGLES OVERLAP ON
TOP EDGE OF FLASHING
CAP AND STORM COLLAR NOT SHOWN FOR CLARITY
Figure 7.23
Step 7.
Continue to assemble pipe sections until the height of the
flue (before adding the termination cap) meets the minimum
local code requirements. Note that for steep roof pitches,
the flue height must be increased. See Roof Pitch Table
(Figure 4.3). In high wind conditions, nearby trees adjoining
rooflines, steep pitched roofs, and other similar factors
can result in poor draft, or down drafting. In these cases
increasing the flue height or switching to the high wind
termination cap may solve this problem.
Step 8.
Slip the storm collar over the pipe, and push it down to
the top of the flashing (Figure 7.24). Use non-hardening
sealant above and below the joint between the storm collar
and the pipe.
SECURE FLASHING WITH
NON-HARDENING SEALANT
AND ROOFING NAILS
Figure 7.24