General venting – Lochinvar KNIGHT XL 801 User Manual
Page 19

19
3
General venting
(continued)
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
 specifi ed in this section.
 
Type “B” double-wall vent with joints and seams sealed as
 specifi ed in this section.
 
AL29-4C, stainless steel material to be sealed to
specifi cation of its manufacturer.
ƽ WARNING Using vent or air intake materials other
than those specifi ed, failure to properly 
seal all seams and joints or failure to follow 
vent pipe manufacturer’s instructions can 
result in personal injury, death or property 
damage. Mixing of venting materials will 
void the warranty and certifi cation of the 
appliance.
NOTICE
The use of double-wall vent or insulated 
material for the combustion air inlet pipe is 
recommended in cold climates to prevent 
the condensation of airborne moisture in 
the incoming combustion air.
Sealing of Type “B” double-wall vent material or galvanized 
vent pipe material used for air inlet piping on a sidewall or 
vertical rooftop Combustion Air Supply System:
a. Seal all joints and seams of the air inlet pipe using either 
 
Aluminum Foil Duct Tape meeting UL Standard 723 or
181A-P or a high quality UL Listed silicone sealant such as
those manufactured by Dow Corning or General Electric.
b. Do not install seams of vent pipe on the bottom of 
 horizontal 
runs.
c. Secure all joints with a minimum of three sheet metal 
 
screws or pop rivets. Apply Aluminum Foil Duct Tape or
silicone sealant to all screws or rivets installed in the vent
pipe.
d. Ensure that the air inlet pipes are properly supported.
The PVC, CPVC, or ABS air inlet pipe should be cleaned and 
sealed with the pipe manufacturer’s recommended solvents 
and standard commercial pipe cement for the material used. 
The PVC, CPVC, ABS, Dryer Vent or Flex Duct air inlet pipe 
should use a silicone sealant to ensure a proper seal at the 
appliance connection and the air inlet cap connection. Dryer 
vent or fl ex duct should use a screw type clamp to seal the vent 
to the appliance air inlet and the air inlet cap. Proper sealing 
of the air inlet pipe ensures that combustion air will be free of 
contaminants and supplied in proper volume.
*Plastic pipe may require an adapter (not provided) to 
transition between the air inlet connection on the appliance 
and the plastic air inlet pipe.
Stainless steel vent
This product has been approved for use with stainless steel 
using the manufacturers listed in Table 3A.
Use only the materials, vent systems, 
and terminations listed in Table 3B. 
DO NOT mix vent systems of different 
types or manufacturers, unless listed in 
this manual. Failure to comply could 
result in severe personal injury, death, or 
substantial property damage.
ƽ WARNING
Installations must comply with applicable 
national, state, and local codes. Stainless 
steel vent systems must be listed as a 
UL-1738 approved system for the United 
States and a ULC-S636 approved system 
for Canada. 
NOTICE
Installation of a stainless steel vent system 
should adhere to the stainless steel vent 
manufacturer’s installation instructions 
supplied with the vent system.
NOTICE
The installer must use a specifi c vent starter 
adapter at the fl ue collar connection, 
supplied by the vent manufacturer to 
adapt to its vent system. See Table 3B for 
approved vent adapters. Discard CPVC 
starter piece.
NOTICE
When a sidewall or vertical rooftop combustion air supply 
system is disconnected for any reason, the air inlet pipe must 
be resealed to ensure that combustion air will be free of 
contaminants and supplied in proper volume.
ƽ DANGER
Failure to properly seal all joints and seams 
as required in the air inlet piping may 
result in fl ue gas recirculation, spillage 
of fl ue products and carbon monoxide 
emissions causing severe personal injury 
or death.
Installation & Operation Manual
