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VERTICAL TERMINATION
1. Set the gas appliance in the desired location. Drop a plumb bob down from the ceiling to
the position of the appliance flue exit, and mark the location where the vent 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 vent will penetrate the roof.
Determine if the ceiling joists, roof rafters or other framing will obstruct the venting system.
You may wish to relocate the appliance or to offset it as shown in Figure 9, to avoid cutting
load bearing members.
2. If an offset is necessary in the attic to avoid obstructions, it is important to support the vent
pipe every 3 feet, to avoid excessive stress on the elbows, and possible joint separation.
Wall straps are available for this purpose (Figure 9).
Wall Strap
Offset with Wall Strap and 45 deg Elbows
Figure 9
3. Assemble the desired lengths of pipe and elbows necessary to reach from the appliance
adapter up through the Round Support Box. Ensure that all pipe and elbow connections are
in their fully twist-locked position. (See Figure 10.)
4. Cut a hole in the roof centered on the small drilled hole made in the roof in Step 1. The hole
should be of sufficient size to meet the 2" requirements for clearance to combustibles.
Continue to assemble lengths of pipe and elbows necessary to reach from the Ceiling
Support Box up through the roof line. Galvanized pipe and elbows may be utilized in the
attic, as well as above the roof line. The galvanized finish is desirable above the roof line
due to its higher corrosion resistance.
NOTES:
Maintain 2" minimum clearance.
To install the Round Support Box/Wall Thimble in a flat ceiling, cut a 10" square hole in the
ceiling centered on the hole drilled in step 1 above. Frame the hole as shown in Figure 11.
INSTALLATION
Vertical Termination Cap
Storm Collar
Roof Flashing
45 Deg.
Elbow
Ceiling Firestop
If area above is a not a room, install firestop above framed hole.
If area above is not a room, install firestop below framed hole.
14
Installing Firestop
Figure 10
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