Heat & Glo MISSION-BAY Owner's Manual page 16

Step 3.
To install the round support box/wall thimble cover in a flat
ceiling, cut a 10 in. (254mm) square hole in the ceiling,
centered on the hole drilled in Step 2. Frame the hole as
shown in Figure 5.13.
FRAMING
Figure 5.13
Step 4.
Assemble the desired lengths of pipe and elbows necessary
to reach from the appliance 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.
NOTE:
(1
) If an offset is necessary in the attic to avoid obstructions,
it is important to support the vent pipe every 3 ft.
(914mm) to avoid excessive stress on the elbows, and
possible separation. Wall straps are available for this
purpose, Figure 5.12, 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 5.14. Verify that the
Page 16
CEILING JOISTS
ROUND CEILING
SUPPORT BOX/WALL
THIMBLE COVER
1-1/2 in. (38mm) LONG
WOOD SCREWS
Heat & Glo · Mission Bay · 250-7512F
chimney is the required height above the roof. See roof pitch
table, Figure 4.3, on page 8 of this manual.
SHINGLES OVERLAP ON
TOP EDGE OF FLASHING
CAP AND STORM COLLAR NOT SHOWN FOR CLARITY
Figure 5.14
Step 7.
Continue to assemble pipe sections until the height of the
vent (before adding the termination cap) meets the minimum
code requirements as outlined in the current CAN/CGA-B149
Installation Codes (in Canada), the National Fuel Gas Code
NFPA 54/ANSI Z223.1 (in USA), or local codes. Note that
for steep roof pitches, the vent height must be increased.
See Roof Pitch Table (Figure 4.3, on page 8). 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 vent 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 5.15). Use non-hardening sealant
above and below the joint between the storm collar and the
pipe.
OPTIONAL HIGH WIND
TERMINATION CAP
SECURE FLASHING WITH
NON-HARDENING SEALANT
Figure 5.15
AND ROOFING NAILS
July 12, 2006