19
3
General
venting
(continued)
Installation & Operation Manual
Air contamination
Pool and laundry products and common household and hobby
products often contain fluorine or chlorine compounds. When
these chemicals pass through the boiler, they can form strong
acids. The acid can eat through the boiler wall, causing serious
damage and presenting a possible threat of flue gas spillage or
boiler water leakage into the building.
Please read the information given in Table 1A listing
contaminants and areas likely to contain them. If contaminating
chemicals will be present near the location of the boiler
combustion air inlet, have your installer pipe the boiler
combustion air and vent to another location, per this manual.
If the boiler combustion air inlet is located in
a laundry room or pool facility, for example,
these areas will always contain hazardous
contaminants.
To prevent the potential of severe personal
injury or death, check for areas and products
listed in Table 1A before installing the boiler
or air inlet piping.
If contaminants are found, you MUST:
• Remove contaminants permanently.
—OR—
• Relocate air inlet and vent terminations
to other areas.
⚠
WARNING
⚠
WARNING
Optional room air
⚠
WARNING
When utilizing the single pipe method,
provisions for combustion and ventilation
Table 3G
Optional Room Air Kit
Commercial applications utilizing the Knight XL boiler may
be installed with a single pipe carrying the flue products to
the outside while using combustion air from the equipment
room. In order to use the room air venting option the following
conditions and considerations must be followed.
• The unit MUST be installed with the appropriate room
air kit (Table 3G).
• The equipment room MUST be provided with properly
sized openings to assure adequate 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.
NOTICE
Optional room air is intended for commercial
applications. Combustion air piping to
the outside is recommended for residential
applications.
Model
Description
Kit Number
400 - 1000
90° Elbow with Screen 100157616
Installing vent and air piping
Use only cleaners, primers, and solvents
that are approved for the materials which
are joined together.
NOTICE
PVC/CPVC
All PVC vent pipes must be glued, properly
supported, and the exhaust must be
pitched a minimum of a 1/4 inch per foot
back to the boiler (to allow drainage of
condensate).
NOTICE
⚠
WARNING
The vent connection to the appliance must
be made with the CPVC pipe section if
PVC/CPVC vent is to be used. The field
provided vent fittings must be cemented
to the CPVC pipe section using an “All
Purpose Cement” suitable for PVC and
CPVC pipe. Use only the vent materials,
primer, and cement specified in Table 3H
to make the vent connections. Failure to
follow this warning could result in fire,
personal injury, or death.
⚠
WARNING
Insulation should not be used on PVC
or CPVC venting materials. The use of
insulation will cause increased vent wall
temperatures, which could result in vent
pipe failure.
This product has been approved for use with the PVC/CPVC
vent materials listed in Table 3H.
Model
Category IV
Standard Vent
Size
Category II
Increaser Size
Maximum
Vent Length
400
4"
6"
150'
500
4"
6"
150'
650
6"
8"
150'
800
6"
8"
150'
1000
6"
8"
150'
Table 3F
Category IV to Category II Conversion Chart
Common venting CAT II:
Flues of multiple appliances may be combined by incorporating
a vent increaser to change the Category IV appliance to a
Category II vent system which can be common vented using
an engineered vent system. An increaser must be used and
the combined engineered vent system must be designed to
ensure that flue products will be properly exhausted from the
building at all times.
Failure to use the correct vent increaser
or a properly sized vent system may result in a hazardous
condition where flue gases spill into an occupied living
space.
Consult a vent designer to determine the diameter of
the common vent pipe required for combined vent installation.
It is recommended that all vent joints and seams are sealed
gastight. This vent system has specific vent material and
installation requirements. The negative draft in a conventional
vent installation must be within the range of 0.02 to 0.08 inches
w.c. to ensure proper operation. Make all draft readings while
the unit is in stable operation (approximately 2 to 5 minutes).
air must be in accordance with Air for Combustion and
Ventilation, of the latest edition of the National Fuel Gas
Code, ANSI Z223.1, in Canada, the latest edition of CGA
Standard B149 Installation Code for Gas Burning Appliances
and Equipment, or applicable provisions of the local building
codes.
