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side of the vent pipe
and the combustible
surfaces of the en-
closure. Do not fill re-
quired air spaces with insulation.
3. If venting system passes through an attic space an at-
tic insulation shield must be installed to prevent con-
tact between pipe sections and the insulation. Nail the
base to floor of attic and adjust shield for appropriate
insulation level, then attach the collar at the top of as-
sembly. (Fig. 39) For vaulted ceilings, the attic insu-
lation shield cannot be installed. To prevent building
insulation and other debris from entering the support
box or contacting the pipe, a chase enclosure can be
constructed around the support box. Ensure proper
clearance to combustibles are maintained.
Cathedral Ceiling Installation
Step 1. Follow installation Step 1 and 2 under Vertical
Termination.
Step 2. Using the plumb bob, mark the centerline of the
venting system on the ceiling and drill a small hole through
the ceiling and roof at this point. From the roof, locate the
drill hole and mark the outline of the Cathedral Ceiling
Support Box.
Step 3. Remove shingles or other roof covering as neces-
sary to cut the rectangular hole for the support box. Cut
the hole 1/8" (3 mm) larger than the support box outline.
Step 4. Lower the support box through the hole in the roof
until each side of the bottom of the support box protrudes
at least 2" (51 mm) below the ceiling. (Fig. 40) Align the
support box both vertically and horizontally with a level.
20306761
High Wind Vertical
Termination
Storm Collar
Roof Flashing
Optional
Low Profile
Termination
Cap
Secure Flashing
with Non-harden-
ing Sealant and
Roofing Nails
ST990
ST990
above roof
8/07
Intrepid® Direct Vent - Rear Vent Gas Heater
Figure 38
Figure 39
Attic
Insulation Shield
Required
Clearance
ST991
Figure 40
Cathedral Ceiling
Support Box
Temporarily tack the support box in place through the in-
side walls and into the roof sheathing.
Step 5. Using tin snips, cut the support box from the top
corners down to the roofline, and fold the resulting flaps
over the roof sheathing. The flaps may be trimmed as
needed. (Fig. 41) Before nailing it to the roof, run a bead
of non-hardening sealant around the support box to make
a seal between the support box and the roof. Clean out
any combustible material from inside the support box.
Step 6. Follow Steps 4 and 5 of the Vertical Installation
instructions.
Step 7. Place the support clamp (provided with the sup-
port box) inside the support box (at the bottom), and se-
cure to the pipe section. The clamp allows the support
box to support the weight of the pipe sections. Continue to
add pipe sections until you are above the roofline.
Nails
Minimum
Clearance
Minimum
Clearance
ST991
Level
attic insul shield
8/07
ST992
Cut Hole 1/8"
Larger than Sup-
port Box
ST992
clg support box
8/07
2" Min. Below
Finished Ceil-
ing
21
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