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5 Vertical direct venting
Vent/air termination – vertical
Multiple vent/air terminations
1. When terminating multiple Knight wall mount boilers,
terminate each vent/air connection as described in this
manual (FIG. 5-2).
Terminate all vent pipes at the same height
and all air pipes at the same height to
avoid possibility of severe personal injury,
death, or substantial property damage.
2. Place roof penetrations to obtain minimum clearance of
12 inches between edge of air intake elbow and adjacent
vent pipe of another boiler for U.S. installations (see
FIG. 5-2). For Canadian installations, provide clearances
required by CSA B149.1 Installation Code.
3. The air inlet of a Knight wall mount boiler is part of a
direct vent connection. It is not classified as a forced air
intake with regard to spacing from adjacent boiler vents.
Figure 5-2 Vertical Terminations with Multiple Boilers
Figure 5-3 Alternate Vertical Terminations with Multiple
Boilers
ƽ WARNING
30
Installation & Operation Manual
Prepare roof penetrations
1. Air pipe penetration:
a. Cut a hole for the air pipe. Size the air pipe hole as
close as desired to the air pipe outside diameter.
2. Vent pipe penetration:
a. Cut a hole for the vent pipe. For either combustible
or noncombustible construction, size the vent pipe
hole with at least a 1/2 inch clearance around the
vent pipe outer diameter:
• 3½ inch hole for 2 inch vent pipe
• 4½ inch hole for 3 inch vent pipe
b. Insert a galvanized metal thimble in the vent pipe
hole.
3. Space the air and vent holes to provide the minimum
spacing shown in FIG. 5-1A, page 29.
4. Follow all local codes for isolation of vent pipe when
passing through floors, ceilings, and roofs.
5. Provide flashing and sealing boots sized for the vent pipe
and air pipe.