Napoleon GDS25N GDS25P Installation And Operation Instructions Manual page 11

DEFINITIONS
for the following symbols used in the venting calculations
and examples are:
> - greater than
> - equal to or greater than
< - less than
< - equal to or less than
H
- total of both horizontal vent lengths (H
T
(H ) in feet
O
H
- combined horizontal vent lengths in feet
R
H
- offset factor: .03(total degrees of offset - 135°*) in
O
feet
V
- combined vertical vent lengths in feet
T
HORIZONTAL TERMINATION
when (H ) < (V )
T T
90°
FIGURE 5
Simple venting confi guration (only one 45º and 90° elbow)
40
39
30
REQUIRED
VERTICAL
20
R I S E I N
FEET (V )
10
T
0
2.5
CALCULATED HORIZONTAL VENT RUN
PLUS OFFSETS IN FEET (H
The shaded area within the lines represents acceptable
values for H and V .
T T
) and offsets
R
45º
5 7.5 10 12.5 15 17.5
)
T
ELBOW VENT LENGTH VALUES
1°
15°
30°
45°*
90°*
* the fi rst 45º and 90° offset has a zero value and is
shown in the formula as -45° and -90º respectively or
-135º when combined.
For vent confi gurations requiring more than one 45º and 90°
elbow, the following formulas apply:
Formula 1: H < V
T
Formula 2: H + V
T
Example 1:
FIGURE 6
45º
V
= 8 ft
1
V = V
= 8 ft
T 1
H
= 2.5 ft
1
H
= 2 ft
2
H = H + H
= 2.5 + 2 = 4.5 ft
R 1 2
H
= .03(one 45º elbow + two 90º elbows - 135º)
O
=0.3(225-135º) = 2.7ft
H = H + H
= 4.5 + 2.7 = 7.2 ft
T R O
20
H + V
= 7.2 +8 =15.2ft
T T
H < V
Formula 1:
T
7.2 < 8
H + V
Formula 2:
T
15.2 < 40
Since both formulas are met, this vent confi guration is
acceptable.
feet inches
0.03 0.5
0.45 6.0
0.9 11.0
1.35 16.0
2.7 32.0
T
< 40 feet
T
H
90°
2
V
1
H
1
90°
T
< 40 feet
T
W415-0547 / B / 05.08.06
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