1-15
INSTALLATION
SL 80-399 MODULATING GAS BOILER
SL 26-260 G3, SL 40-399 G3 MODULATING GAS BOILERS
1.4.7 “Direct Vent” Combustion Air Intake Piping
The direct vent option uses piping from the outside to supply combustion air directly to the
boiler’s combustion air connection.
Figure 18: Direct vent combustion air intake
SL 26-260 G3
INTAKE PIPE SIZE
MAXIMUM EQUIVALENT LENGTH
Sched.40; Rigid PPs
3"
200' each side
90° vent elbow
allow 8' equivalent
90° long sweep elbow
allow 5' equivalent
45° elbow
allow 3' equivalent
PPs 87-90° elbows
use 8' equivalent
3" Stainless Sidewall Terminal
IBC P/N 180-149 (P-257)
No additional allowance required
Flexible PPs
3" PPs Flexible (SL 26-260
G3)
60' max., actual lineal x 3.33 = equivalent
Table 4A: Maximum Intake Pipe Venting Length for SL 26-260 G3
WARNING
In addition to preventing
ingestion of chemical
contaminants, care must be
taken to ensure air intake
terminals are not installed in
locations where contamination
might occur due to ingestion of
particulate foreign material (dust,
dirt and debris).
NOTE
Care must be taken when
installing air intake piping to
ensure that a “trap” is not formed
in the piping so as to allow a
build-up of water, and blockage
of intake air.
Such blockage will result in a
boiler safety shut-down.
WARNING
Intake air openings must be
configured such that rain or
other forms of moisture cannot
enter the air intake piping
system. Otherwise serious
damage to the boiler may result.
NOTE
Combustion fan blockages
can occur when environmental
particulate and foreign matter
contaminants (leaves, dust,
dandelion & cottonwood fluff,
etc) are drawn into the air intake.
In areas where this problem
is suspected to be an issue,
intake air filtration should be
considered. Contact Factory.
Filters should be checked and
cleaned or replaced on a regular
schedule based on the severity
of the problem.
