KBD Series Manual
23
Determine the number of 90 degree elbows in the vent system. (two 45 degree elbows count as one 90 degree elbow.)
Refer to the tables below to find the maximum vent length based on the number of elbows and termination style.
Maximum Equivalent Vent Length Tables:
Maximum vent lengths are specific to the fuel type of the tankless water heater. It is imperative when
performing equivalent vent length calculations that the gas type be taken into consideration.
ATTENTION
OPTION 2:
Natural Gas Units
Total Equivalent Vent Length (Intake/outlet) for Twin Pipe 4" PVC/CPVC
Maximum Vent Length
100 Feet
Termination Type
IPEX Concentric
Vent Kit
Snorkel
Termination
Side Wall Tee
Termination
Low Profile
Termination
Termination Equivalent Length in feet
(meters) (Already factored into the straight
pipe lengths below)
20 (6.1)
15 (3.0)
5 (1.5)
5 (1.5)
# of 90° Elbows (each: 5 equivalent feet)
Max. straight pipe vent length in feet (meters)
0
80 (24.4) **
85 (25.9) **
95 (29.0) **
95 (29.0) **
1
75 (22.9) **
80 (24.4) **
90 (27.4) **
90 (27.4) **
2
70 (21.3) **
75 (22.9) **
85 (25.9) **
85 (25.9) **
3
65 (19.8) **
70 (21.3) **
80 (24.4) **
80 (24.4) **
4
60 (18.3) **
65 (19.8) **
75 (22.9) **
75 (22.9) **
5
55 (16.8) **
60 (18.3) **
70 (21.3) **
70 (21.3) **
6
50 (15.2) **
55 (16.8) **
65 (19.8) **
65 (19.8) **
**SW 1 in DIPSW 1 is “OFF” for lengths greater than or equal to 21 feet
Natural Gas Units
Total Equivalent Vent Length (Intake/outlet) for Twin Pipe 3" PVC/CPVC
Maximum Vent Length
65 Feet
Termination Type
IPEX Concentric
Vent Kit
Snorkel
Termination
Side Wall Tee
Termination
Low Profile
Termination
Termination Equivalent Length in feet
(meters) (Already factored into the straight
pipe lengths below)
20 (6.1)
15 (3.0)
5 (1.5)
5 (1.5)
# of 90° Elbows (each: 5 equivalent feet)
Max. straight pipe vent length in feet (meters)
0
45 (13.7) **
50 (15.2) **
60 (18.3) **
60 (18.3) **
1
40 (12.2) **
45 (13.7) **
55 (16.8) **
55 (16.8) **
2
35 (10.7) **
40 (12.2) **
50 (15.2) **
50 (15.2) **
3
30 (9.1) **
35 (10.7) **
45 (13.7) **
45 (13.7) **
4
25 (7.6) **
30 (9.1) **
40 (12.2) **
40 (12.2) **
5
20 (6.1) **
25 (7.6) **
35 (10.7) **
35 (10.7) **
6
15 (4.6) **
20 (6.1) **
30 (9.1) **
30 (9.1) **