Filter
Top Products
Installation & Operation Manual
15
3 General venting (continued)
Air intake/vent connections
1. Combustion Air Intake Connector (FIG. 3-5) - Used
to provide combustion air directly to the
unit from outdoors. A fitting is provided on the unit
for final connection. Combustion air piping must be
supported per guidelines listed in the National
Mechanical Code, Section 305, Table 305.4 or as local
codes dictate.
2. Vent Connector (FIG. 3-5) - Used to provide
a passageway for conveying combustion gases to the
outside. A transition fitting is provided on the unit for
final connection. Vent piping must be supported per
the National Building Code, Section 305, Table 305.4 or
as local codes dictate.
Combustion air piping to the outside
MUST BE used. Use of combustion air
from the room via louvers, plenums, or
any other device is not authorized.
NOTICE
VENT
AIR
Figure 3-5 Near Boiler Venting Model 50
Maximum allowable combustion air and
vent piping lengths are as follows:
The Knight wall mount boiler uses model specific combustion
air intake and vent piping sizes as detailed in Table 3B below.
Model 2" Max Vent/Air 3" Max Vent/Air
50 40 feet 100 feet
80 40 feet 100 feet
105 40 feet 100 feet
150 N/A 100 feet
210 N/A 100 feet
Increasing or decreasing the size of the
combustion air or vent piping beyond the
sizes listed in Table 3B is not authorized.
NOTICE
When determining equivalent combustion air and vent length,
add 5 feet for each 90° elbow, 3 feet for each 45° elbow, and 3 feet
for the concentric vent kit, see example below.
EXAMPLE: 20 feet of PVC pipe + (4) 90° elbows + (2) 45°
elbows + (1) concentric vent kit = 49 equivalent feet of piping.
Table 3B Maximum Combustion Air and Vent Piping
Lengths
Note: The minimum combustion air and vent piping length is
12 equivalent feet.
Air inlet pipe materials:
The air inlet pipe(s) must be sealed. Choose acceptable
combustion air inlet pipe materials from the following list:
PVC, CPVC or ABS
Dryer Vent or Sealed Flexible Duct (not recommended
for rooftop air inlet)
Galvanized steel vent pipe with joints and seams sealed as
specified in this section.
Type “B” double-wall vent with joints and seams sealed as
specified in this section.
*Plastic pipe may require an adapter (not provided) to
transition between the air inlet connection on the appliance and
the plastic air inlet pipe.
For 2" vent / air lengths greater than 40 feet,
consult the factory.
NOTICE