Equivalent Vent Length Calculation Example - Viessmann Vitodens 200-W WB2B Series Installation Instructions Manual

Direct Venting (Two-pipe System)
Vent Length Requirements
Equivalent vent length calculation example - stainless steel
system with plastic air intake pipe
Vent type
Exhaust vent pipe
Air intake pipe
IMPORTANT
Always include vent termination length in calculations.
Equivalent vent length calculation example - CPVC system
Type of fitting
90° long sweep elbow (CPVC)
45° long sweep elbow (CPVC)
48
(continued)
Type of fitting
90° elbow (stainless steel)
45° elbow (stainless steel)
90° elbow (ABS/PVC)
45° elbow (ABS/PVC)

Equivalent vent length calculation example

(Vitodens WB1B and B2TA systems diameter 3 in.)
Maximum allowable equivalent length is 164 ft. (50 m)
(see table and illustration below and illustration on page
46).
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)
Equivalent vent length calculation example
(Vitodens WB1B systems diameter 2 in.)
Maximum allowable equivalent length is 98 ft. (30 m)
(see table on page 43 and illustration below)
2 x 90º elbow.....................................10 ft. (3.05 m)
4 x 45º elbow.....................................12 ft. (3.66 m)
Exhaust vent pipe................................10 ft. (3.05 m)
Air intake pipe.....................................10 ft. (3.05 m)
Combined total equivalent vent length
(a+b).................................................42 ft. (12.81 m)
Vitodens Rigid and Flex Venting Systems Installation
Equivalent length ft. (m)
Equivalent length ft. (m)
5 (1.52)
3 (0.91)
3 (0.91)
2 (0.61)
5 (1.52)
3 (0.91)