Min./Max. Combustion Air & Vent Piping Lengths; Vent And Air Piping; Optional Room Air - Lochinvar KNIGHT 399 Installation & Operation Manual

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General venting
The Knight XL uses model specific combustion air intake and
vent piping sizes as detailed in Table 3D below.
Table 3D Air Intake/Vent Piping Sizes
Model Air Intake
399 - 600 4 inches (102 mm)
700 - 800 4 inches (102 mm)
Increasing or decreasing combustion air
NOTICE
or vent piping is not authorized.
Minimum / Maximum
combustion air and vent piping lengths
are as follows:
Combustion Air = 12 equivalent feet (3.7 m) minimum / 100
equivalent feet (30.5 m) maximum
Vent = 12 equivalent feet (3.7 m) minimum / 100 equivalent
feet (30.5 m) maximum
When determining equivalent combustion air and vent
length, add 5 feet (1.5m) for each 90° elbow and 3 feet (.9 m)
for each 45° elbow.
EXAMPLE: 20 feet (6 m) of PVC pipe + (3) 90° elbows + (3)
45° elbows + (1) concentric vent kit (CVK3007) = 49
equivalent feet (15 m) of piping.
The appliance output rating will reduce by
NOTICE
up to 1.5% for each 25 feet (68 m) of vent
length.
Table 3E Concentric Vent Kit Equivalent Vent Lengths
Model Kit Number
399 CVK3007
500 CVK3007
600 CVK3007
Removing from existing vent
Follow the instructions in Section 1, page 12 of this manual
when removing a boiler from an existing vent system.
(continued)

Vent and air piping

Vent and air system:
Vent
4 inches (102 mm)
6 inches (152 mm)
You must also install air piping from outside to the boiler air
intake adapter. The resultant installation is direct vent (sealed
combustion).
You may use any of the vent/air piping methods covered in this
allowable manual. Do not attempt to install the Knight XL using any
other means.
Vent, air piping and termination:
The Knight XL vent and air piping can be installed through the
roof or through a sidewall. Follow the procedures in this
manual for the method chosen. Refer to the information in this
manual to determine acceptable vent and air piping length.

Optional room air

Equivalent
Commercial applications utilizing the Knight XL boiler may be
Vent Length
installed with a single pipe carrying the flue products to the
5 Feet (1.5 m)
outside while using combustion air from the equipment room.
30 Feet (9 m) In order to use the room air venting option the following
conditions and considerations must be followed.
30 Feet (9 m)
Installation & Operation Manual
Installation
NOTICE
requirements and with the National Fuel Gas
Code, ANSI Z223.1 for U.S. installations or
CSA B149.1 for Canadian installations.
DO NOT mix components from different
WARNING
systems. The vent system could fail, causing
leakage of flue products into the living
space. Use only approved stainless steel,
PVC or CPVC pipe and fittings.
PVC/CPVC use with primer and cement
specifically designed for the material used.
Optional room air is intended for
NOTICE
commercial applications. Combustion air
piping to the outside is recommended for
residential applications.
• The unit MUST be installed with the appropriate
room air kit (Table 3F).
• The equipment room MUST be provided with
properly sized openings
combustion air. Please refer to instructions provided
with the room air kit.
• There will be a noticeable increase in the noise level
during normal operation from the inlet air opening.
• Using the room air kit makes the unit vulnerable to
combustion air contamination from within the
building. Please review Section 1, Prevent
Combustion Air Contamination, to ensure proper
installation.
• Vent system and terminations must comply with the
standard venting instructions set forth in this manual.
must comply with local
For
to assure adequate
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