Napoleon HD81NT Installation And Operating Instructions Manual page 17

Simple venting configurations.
For vent configurations requiring more than two 90° elbows the following formulas apply:
Formula 1: H < 3V
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) = 4.5FT (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) = 20.6 FT (6.3m)
T T
Formula 1: H < 3V
T T
3V = 3FT (0.9m) x 4.5FT (1.4m) = 13.5FT (4.1m)
T
16.1FT (4.9m) > 13.5FT (4.1m)
Since this formula is not met, this vent configuration is unacceptable.
Formula 2: H + V < 40 feet (12.2m)
T T
20.6FT (6.3m) < 40 (12.2m)
Since only formula 2 is met, this vent configuration is unacceptable and a new appliance location or vent configuration will
need to be established to satisfy both formulas.
(H ) > (V )
T T
See graph to determine the required vertical rise V
20 (6.1)
19 (5.8)
REQUIRED
VERTICAL
RISE IN FEET
10 (3.1)
(METERS) V
T
3 (0.9)
0
HORIZONTAL VENT RUN PLUS OFFSET IN FEET (METERS) H
The shaded area within the lines represents acceptable
required horizontal run H
5 10 15 20
(1.5) (3.1) (4.6) (6.1)
values for H and V
T T
90°
90°
H
V
V
1
2
1
18.1_2B
17
for the
T
EN
.
T
25 30
(7.6) (9.1)
T
V
3
H
2
90°
90°
W415-0687 / G / 08.26.13