Bradford White PDX1-40S6FBN Installation And Operating Instruction Manual page 14

Venting continued-
Table 2 lists the venting distances allowed with 4" (10.2 cm) diameter vent pipe.
When venting with 4" (10.2 cm) vent pipe, use a 4" (10.2 cm) to 3" (7.6 cm)
reducer to exit through the building wall with 3" (7.6 cm) vent pipe. Use the 3"
(7.6 cm) vent terminal supplied with the water heater to terminate on the
outside of the building. If the length of 3" (7.6 cm) vent pipe needed to go
through the wall is greater than 14" (35.5 cm), use 4" (10.2 cm) to go through
the wall and reduce to 3" (7.6 cm) vent pipe immediately after exiting the
outside wall. Refer to the venting illustrations on the following pages. Make
sure the vent pipe terminal elbow fitting is at least 1" (2.5 cm) away from the
edge of the wall.
The minimum equivalent length for the exhaust portion of the vent is 7
feet. The maximum equivalent vent length for the exhaust is 60 feet for
3" diameter pipe (50 feet for the 75 gal.) and 100 feet for 4" diameter
pipe (90 feet for the 75 gal.). The intake portion of the vent must be
equal to or less than the vent length of the exhaust. The tables below
are provided for your quick reference, some installations may require a
greater number of elbows. When calculating equivalent vent length,
one 90º elbow is equivalent to 5 feet.
Terminating
Through the Wall
Through the Wall
Through the Wall
Through the Wall
Through the Roof
Through the Roof
Through the Roof
Through the Roof
TABLE 1 - VENT CONNECTOR LENGTHS
FOR 3" (7.6 cm) DIAMETER VENT PIPE
# of Elbows
(excl. vent
term.)
1
2
3
4
0
1
2
3
IMPORTANT
Maximum straight
Length ft (m)
48, 65
gal.
55 (16.8)
50 (15.2)
45 (13.7)
40 (12.2)
60 (18.3)
55 (16.8)
50 (15.2)
45 (13.7)
14
Minimum
straight
Length
75 gal.
45 (13.7) 2 (.6)
40 (12.2) 2 (.6)
35 (10.7) 2 (.6)
30 (9.1) 2 (.6)
50 (15.2) 7 (2.1)
45 (13.7) 7 (2.1)
40 (12.2) 7 (2.1)
35 (10.7) 7 (2.1)
ft (m)