INSTALLATION AND OPERATION INSTRUCTIONS
1-16
SL 26-260 G3, SL 40-399 G3 MODULATING GAS BOILERS
SL 40-399 G3
INTAKE PIPE SIZE
MAXIMUM EQUIVALENT LENGTH
Sched.40; Rigid PPs
4" CPVC / Rigid PPs
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
3" PVC (to adapt to SST)
for each 1' allow 3.2' equivalent
Flexible PPs
4" PPs Flexible
160' max, using 1.2 x for equivalent length
Table 4B: Maximum Intake Pipe Venting Length for SL 40-399 G3
For the inlet air – 4" Schedule 40 PVC, CPVC, ABS, or PPs piping of any type is
permitted.
Care must be taken to ensure adequate separation is maintained between the air intake
inlet and the vent terminal. Refer to the vent terminal configuration drawings in the Vent
Termination section above.
Support should be provided for intake piping, particularly so for horizontal runs (follow
local code).
1.4.8 “Indoor Air” Combustion Air Intake
An “Indoor Combustion Air installation”, as described herein, is one in which air for
combustion is taken from the ambient air around the boiler.
WARNING
When using Indoor Air options,
adequate combustion air must
be supplied to the boiler room
according to the requirements of all
applicable codes.
Figure 19: Indoor combustion air intake
NOTE
It is not permitted to add to the
exhaust length by transfer of
unused intake allowance.
NOTE
Combustion air piping - if used - is
inserted directly into the 4” female
stainless steel fitting on the top,
right side of the boiler and run
horizontally or vertically to the
outdoors. Screen material can be
placed at the inlet as appropriate for
the environment (e.g. insects, dust).
