305, 505, 705 Indoor Manual
23
Example: If you have one elbow then your maximum vent length is 35 feet (10.7 m). If your actual length is
greater than 15 ft (4.6 m) then move dip switch no. 1 (SW1) to OFF.
Maximum Vent Length
1. Determine the number of 90 degree elbows in the vent system. (Two 45 degree elbows count as one 90
degree elbow.)
2. Refer to the table to find the maximum vent length based on the number of elbows.
3. Follow the applicable note.
If you have a longer vent length, dip switch no. 1 is required to be in the OFF position. This ensures the water
heater will run properly. Blocked flue error codes and shutdowns may result if dip switch no. 1 is not in the
correct position. On the 505 model, the maximum water flow capacity will be reduced by about 10% when dip
switch no. 1 is OFF.
NOTICE
Number of 90° Elbows
0
1
2
3
4
5
6
41 ft
1
(12.5 m)
35 ft
2
(10.7 m)
29 ft
3
(8.8 m)
23 ft
4
(7.0 m)
17 ft
4
(5.2 m)
11 ft
4
(3.4 m)
5 ft
4
(1.5 m)
1
If the length is greater than 21 ft (6.4 m) then move
dip switch no. 1 (SW1) to OFF.
2
If the length is greater than 15 ft (4.6 m) then move
dip switch no. 1 (SW1) to OFF.
3
If the length is greater than 9 ft (2.7 m) then move
dip switch no. 1 (SW1) to OFF.
4
Move dip switch no. 1 (SW1) to OFF.
Notes
1234
Venting
Instructions
Switch No.
F
O
F
8
5
7
6
4
3
ON
1
2
