20
W415-1004 / B / 08.10.12
Example:
V
1
= 1.5 FT
V
2
= 5 FT
V
T
=
V
1
+ V
2
= 1.5 + 1 + 5 = 6.5 FT
H
1
= 1 FT
H
2
= 1 FT
H
3
= 10.75 FT
H
R
=
H
1
+ H
2
+ H
3
= 1 + 1 + 10.75 = 12.75 FT
H
O
= .03 (four 90° one 45° elbow - 90°)
= .03 (360° + 45° - 90°) = 6.75 FT
H
T
=
H
R
+ H
O
= 12.75 + 6.75 = 19.5 FT
H
T
+ V
T
= 19.5 + 6.5 = 26 FT
Formula 1:
H
T
< 3 V
T
3 V
T
=
3 x 6.5 = 19.5 FT
19.5 = 19.5
Formula 2:
H
T
+ V
T
< 35 FT
26 < 35
Since both formulas are met, this vent configuration is acceptable.
90°
V
1
V
2
H
1
H
2
90°
90°
H
3
45°
18.4_3