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20
VENTING, INLET AIR AND CONDENSATE
D. EXHAUST VENT AND INTAKE AIR PIPE
SIZING
1. For the PI-T50 and PI-T80 Boilers the exhaust vent
and air intake pipes should be 2" Schedule 40 or 80.
2. For the PI-80, PI-140, PI-199 the exhaust vent and
air intake pipes should be 3" Schedule 40 or 80.
3. The total combined equivalent length of exhaust
vent and intake air pipe should not exceed 85 feet.
a. The equivalent length of elbows, tees, and other
fittings are listed in Table 5.1.
b. For example: If the exhaust vent has two 90°
elbows and 10 feet of PVC pipe we will
calculate:
Exhaust Vent Pipe Equivalent Length = (2x5)+10=20 feet
Further, if the intake air pipe has two 90° elbows,
one 45° elbow and 10 feet of PVC pipe, the
following calculation applies:
Air Intake Pipe Equivalent Length = (2x5)+3+10=23 feet
Finally, if a concentric vent kit is used we find:
Total Combined Equivalent Length = 20+23+3=46 feet
Therefore, the total combined equivalent length
is 46 feet which is well below the maximum of
85 feet.
c. The intake air pipe and the exhaust vent are
intended to penetrate the same wall or roof of
the building.
d. Effort should be made to keep a minimum
difference in equivalent length between the air
intake pipe and the exhaust vent.
Figure 5.1: Location of exit terminals of mechanical draft and direct-vent venting systems.
(Reference: National Fuel Gas Code ANSI Z223.1/NFPA 54 2002).
Fitting Description Equivalent Length
Elbow, 90°, Short Radius 5
Elbow, 45°, Short Radius 3
Coupling 0
Air Intake Tee 0
Concentric Vent Kit 3
V1000 & V500 Vent Kit 0
Table 5.1: Fitting Equivalent Length Table
Figure 5.2: Multiple Pinnacle Vent Spacing