VENTING
15
i.
The only approved vent termination is a 3" (76
mm) 90° elbow. Refer to Figure 4.4. Vent pipe
must be sealed to the thimble (or outside wall if-
non-combustible construction) using silicone to
prevent recirculation of flue products into the
structure.
*Maximum Vent Length to be reduced by 5 feet (1.5
meters) for each 90° elbow added that is
manufactured by Z-Flex
®
, Heat-Fab
®
and Protech.
*Maximum Vent Length to be reduced by 7-1/2 feet
(2.3 meters) for each 90° elbow added that is
manufactured by Flex-L.
The outside vent terminal (90° Elbow) is not
included in Equivalent Vent Length.
7. Refer to Figure 4.2 for vertical offset option. The
maximum offset is 5 feet. With the exception of the
last 90° elbow which serves as the vent terminal, the
additional elbows and straight vent pipe must be
considered when determining maximum vent length.
Provide a horizontal drain tee as described in
Section D
. Direct Exhaust; Vertical Venting
.
Figure 4.2: Direct Exhaust, Sidewall Venting with
Vertical Off-Set
Figure 4.3: Vent Pipe Adapters
50 feet (15 m)
50 feet (15 m)
45 feet (13.7 m)
45 feet (13.7 m)
70
105
140
165
Boiler Size
2-1/2 feet (762 m)
2-1/2 feet (762 m)
2-1/2 feet (762 m)
2-1/2 feet (762 m)
Table 4.2: Equivalent Vent Length
*Equivalent Length of 3" diameter
Stainless Steel Vent Pipe
Minimum Vent Length Maximum Vent Length
