31
5
Vertical direct venting
(continued)
Vent/air termination – vertical
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:
• 5½ inch hole (140 mm) hole for 4 inch (102 mm)
vent
pipe
• 7½ inch hole (191 mm) hole for 6 inch (152 mm)
vent
pipe
b. Insert a galvanized metal thimble in the vent pipe
hole (when required by local codes).
3. Space the air and vent holes to provide the minimum
spacing shown in FIG.’s 5-1A and 5-1B, page 30.
4. Follow all local codes for isolation of vent pipe when
passing through fl oors, ceilings, and roofs.
5. Provide
fl ashing and sealing boots sized for the vent pipe
and air pipe.
Multiple vent/air terminations
1. When terminating multiple Knight XL 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 recirculation of fl ue products and
the possibility of severe personal injury,
death, or substantial property damage.
2. Place roof penetrations to obtain minimum clearance
of 12 inches (305 mm) 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. Th
e air inlet of a Knight XL boiler is part of a direct vent
connection. It is not classifi ed as a forced air intake with
regard to spacing from adjacent boiler vents.
12" (305 MM) MINIMUM
VERTICALLY FROM VENT
OUTLET TO ANY AIR INLET
12" (305 MM) MINIMUM FROM EDGE
OF AIR INTAKE PIPE TO ADJACENT
VENT PIPE FROM ANOTHER BOILER
AIR
AIR
VENT
VENT
Figure 5-2 Vertical Terminations with Multiple Boilers
VENT
VENT
AIR
AIR
12" (305 MM) MINIMUM
VERTICALLY FROM VENT
OUTLET TO ANY AIR INLET
Figure 5-3 Alternate Vertical Terminations with Multiple
Boilers
WARNING
Installation & Operation Manual
