Installation & Operation Manual
15
3
General venting
(continued)
Air intake/vent connections
1.
Combustion Air Intake Connector
(FIG.’s 3-5 and 3-6)
- 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.’s 3-5 and 3-6) - 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
3” CPVC PIPE SUPPLIED WITH BOILER
MUST BE USED FOR VENT CONNECTION
NOTE: CPVC VENT PIPE AND VENT FITTINGS MUST BE USED IN CLOSET
AND ALCOVE INSTALLATIONS.
Figure 3-5
Near Boiler Venting Models 80 - 210
4” CPVC PIPE SUPPLIED WITH BOILER
MUST BE USED FOR VENT CONNECTION
NOTE: CPVC VENT PIPE AND VENT FITTINGS MUST BE USED IN CLOSET
AND ALCOVE INSTALLATIONS.
Figure 3-6
Near Boiler Venting Model 285
The Knight boiler uses model specific combustion air intake
and vent piping sizes as detailed in Table 3B below.
Model
Air Intake
Vent
80 - 210
3 inches
3 inches
285
4 inches
4 inches
Table 3B
Air Intake/Vent Piping Sizes
Increasing or decreasing combustion air
or vent piping is not authorized.
NOTICE
Minimum / Maximum allowable
combustion air and vent piping lengths
are as follows:
Combustion Air
= 12 equivalent feet minimum /
100 equivalent feet maximum
Vent
= 12 equivalent feet minimum / 100 equivalent feet
maximum
When determining equivalent combustion air and vent
length, add 5 feet for each 90° elbow and 3 feet for each 45°
elbow.
EXAMPLE:
20 feet of PVC pipe + (4) 90° (2) 45°
(1) concentric vent kit (CVK3003) = 49 equivalent
feet of piping.
Model
Kit Number
Equivalent Vent
Length
80 - 210
CVK3003
3 feet
285
CVK3007
3 feet
Table 3C
Equivalent Vent Lengths
The appliance output rating will reduce by
up to 1.5% for each 25 feet of vent length.
NOTICE
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.