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Installation & Operation Manual
24
5 Vertical direct venting
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:
• 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. 5-1, page 23.
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.
Termination and fittings
1. If venting a WB 50 - 105 with 2" vent or a WB 150 - 210 with
3" vent, remove the two bird screens secured inside one of
the two elbows and secure it into the vent termination
coupling. If venting a WB 50 - 105 with 3" vent, insert the
3" bird screens provided with the boiler inside one field
supplied elbow and one into the vent termination coupling.
2. The air piping must terminate in a down-turned 180°
return bend as shown in FIG. 5-1. Locate the air inlet pipe
no further than 2 feet from the center of the vent pipe. This
placement avoids recirculation of flue products into the
combustion air stream.
3. The vent piping must terminate in an up-turned coupling as
shown in FIG. 5-1. The top of the coupling must be at least
1 foot above the air intake. The air inlet pipe and vent pipe
can be located in any desired position on the roof, but must
always be no further than 2 feet apart and with the vent
termination at least 1 foot above the air intake.
4. Maintain the required dimensions of the finished
termination piping as shown in FIG. 5-1.
5. Do not extend exposed vent pipe outside of building more
than shown in this document. Condensate could freeze and
block vent pipe.
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