Installation guide

Direct Venting (Two-pipe System)
61
Vent Length Requirements
Maximum equivalent vent length - stainless steel system with plastic air intake pipe
Table 43. (see also fig. 55)
Vent type Type of fitting Equivalent length
ft./m
Exhaust vent pipe 90° elbow
(stainless steel)
3 / 0.91
45° elbow
(stainless steel)
2 / 0.61
Air intake pipe 90° elbow
(ABS/PVC)
5 / 1.52
45° elbow
(ABS/PVC)
3 / 0.91
Equivalent vent length calculation example
(Vitodens WB1B and WB2B system diameter 3”)
Maximum allowable equivalent length is 164 ft. / 50 m
(see table 39 and fig. 49 on page 56)
2 x 90º stainless steel elbow 6 ft./1.83 m
...........................
2 x 45º stainless steel elbow 4 ft./1.22 m...........................
Air intake pipe
1 x 90º plastic (ABS/CPVC/PVC) elbow 5 ft./1.52 m......
1 x 45º plastic (ABS/CPVC/PVC) elbow 3 ft./0.91 m......
Exhaust vent pipe 10 ft./3.05 m..................................................
Air intake pipe 10 ft./3.05 m.........................................................
Combined total equivalent vent length
(a+b) 38 ft./11.58 m
5368 815 v2.0 b
IMPORTANT
Always include vent termination length
in calculations.