Simple venting configurations.
For vent configurations requiring more than two 90° elbows (top exit) or one 90° elbow (rear exit), the following
formulas apply:
Formula 1: H
< 3 V
T
T
Formula 2: H
+ V
< 40 feet (12.2m)
T
T
Example:
V
= 2 FT (0.6m)
1
V
= 1 FT (0.3m)
2
V
= 1.5 FT (0.5m)
3
V
= V
+ V
+ V
= 2FT (0.6m) + 1FT (0.3m) + 1.5FT (0.5m) = 4.5 FT (1.4m)
T
1
2
3
H
= 6 FT (1.8m)
1
H
= 2 FT (0.6m)
2
H
= H
+ H
= 6FT (1.8m) + 2FT (0.6m) = 8 FT (2.4m)
R
1
2
H
= .03 (four 90° elbows - 90°)
O
= .03 (360° - 90°) = 8.1 FT (2.5m)
H
= H
+ H
= 8FT (2.4m) + 8.1FT (2.5m) = 16.1FT (4.9m)
T
R
O
H
+ V
= 16.1FT (4.9m) + 4.5FT (1.4m) = 20.6FT (6.3m)
T
T
Formula 1:
H
< 3.5 V
T
T
3.5 V
T
16.1FT (4.9m) < 13.5 FT (4.1m)
Since this formula is not met, this vent configuration is unacceptable.
Formula 2:
H
+ V
< 40 FT (12.2m)
T
T
16.1FT (4.9m) < 13.5 (4.1m)
Since only formula 2 is met, this vent configuration is unacceptable and a new fireplace location or vent configuration will
need to be established to satisfy both formulas.
(H
) > (V
T
REQUIRED
VERTICAL
RISE IN
FEET
(METERS)V
HORIZONTAL VENT RUN PLUS OFFSET IN FEET (METERS)H
= 3FT (0.9m) x 4.5FT (1.4m) = 13.5 FT (4.1m)
venting requirements
)
T
See graph to determine the required vertical rise V
required horizontal run H
20 (6.1)
19 (5.8)
10 (3.1)
3 (0.9)
T
0
5
10
(1.5)
(3.1)
The shaded area within the lines represents acceptable
values for H
90°
V
1
H
1
for the
T
.
T
15
20
25
30
(4.6)
(6.1)
(7.6)
(9.1)
and H
T
T
90°
V
3
V
H
2
2
90°
90°
18.2_2B
W415-2881 / C / 03.07.22
EN
T
23