Napoleon BGD36CFNTR Installation And Operating Instructions Manual page 12


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: .0(total degrees of offset - 90°*) in
O
feet
V
- combined vertical vent lengths in feet
T
bGD36CF TOP EXIT / HORIzONTAL TERMINATION
when (H ) < (V )
T T
Simple venting configuration (only one 90° elbow)
See graph to determine the required vertical rise V
required horizontal run H
FIGURE 20
For vent configurations requiring more than one 90° elbow,
the following formulas apply:
vertical
r i s e i n
feet
V
T
horizontal vent run Plus offset in feet
The shaded area within the lines represents acceptable
values for H and V
T T
W45-0566 / A / 07..06
) and offsets
R
.
T
.
ELbOW VENT LENGTH VALUES
°
5°
0°
45°
90°*
* the first 90° offset has a zero value and is shown in the
formula as -90°
Formula 1: H
Formula 2: H
for the
T
Example 1:
V
=  ft
1
V
= 8 ft
2
V = V + V
T 1
H
= .5 ft
1
H
=  ft
2
H = H + H
R 1
H
= .0(three 90° elbows - 90°) = .0(70° - 90°) = 5.4
O
ft
H = H + H
T R
H
T
H + V
= 9.9 +  = 0.9 ft
T T
H
Formula :
9.9 < 
H
Formula :
0.9 < 40
Since both formulas are met, this vent configuration is
acceptable.
feet
0.0
0.45
0.9
.5
.7
< V
T T
+ V < 40 feet
T T
90°
V
2
H
1
90°
V
1
=  + 8 =  ft
2
= .5 +  = 4.5 ft
2
= 4.5 + 5.4 = 9.9 ft
O
< V
T T
+ V < 40 feet
T T
inches
0.5
6.0
.0
6.0
.0
H
2
90°
FIGURE 21