
from the roof to the hole previouslydrilled in the ceiling, and mark the spot where the vent will penetratethe roof. Determine if ceiling joists, roof rafters, or olher framing will obstruct the venting system. You may wish to relocate the appliance, or to offset, as shown in Fig. 13,to avoid cuttingloadbearingmembers.
Step 3. to install the Round SupporrBoxMatl
Thimble in a flat ceiling, cut a
Step 4. Assemble the desired lengths of Black Pipe and Elbows necessaryto reachfrom the Appliance adaptor up through the Round Support Box. Insure that all pipe and Elbow connectionsare in their fully
Step 5. Cut a hole in the roof centredon the small drill hole placedin the roof in Step2. The hole should be of sufficientsize to meet the minimumrequirementsfor clearance to combustibles.
Step 6. Connecta section of pipe and extendup throughhole.
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FlG. 14
NOTE:
1 )
2l
lf an offset is necessaryin the attic to avoid obstructions,it is importantto supportthe vent pipe every3 feet,to avoidexcessivestresson the ElLows,and possibleseparationwall. Strapsareavailablefor this purpose.(Fig.13)
Wheneverpossible,use 45" Elbowsinsteadof 90'Elbows.The 45" Elbowoffers less restrictionto the flow of fluegasesand intakeair.
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