Empire Comfort Systems DVLXG75BP90N-1 Installer's Manual page 33

EFFECTIVE LENGTH IS CALCULATED FOLLOWING BY
THE EQUATION:
Equation 1
Effective length=Vertical Run Up + (2 × Vertical Run Down) +
Horizontal Run + (3 × # of 90° elbows) +(1.5 × # of 45°elbows)
EXAMPLE 1
Fireplace V1 H1
Height
3ft 5inch 5ft 4ft
Vertical Run Up = ( Fireplace Height + V1 ) = 3 ft. 5in + 5 ft. =
8 ft. 5in.
Vertical Run Down = 0 ft.
Horizontal Run = (H1 + H2 + H3) = (4 ft. + 5 ft. + 10 ft.) = 19 ft.
Number of Elbows = 3
Effective Length = Vertical Run Up + (2 x Vertical Run Down) +
Horizontal Run + (3 x # of 90° Elbows) + (1.5 x # of 45° Elbows)
Effective Length = 8 ft. 5in + (2 x 0 ft.) + 19 ft. + (3 x 3 Elbows)
+ (1.5 x 0 Elbows)
Effective Length = 36 ft. 5in
VENTING FIREPLACE
H2 H3 Elbows
Effective
Length
5ft 10ft 3 36ft 5in
A
TO BOTTOM
UNIT
Fireplace
Height
3ft 5inch
Total
Vertical Run Up = ( Fireplace Height) = 3 ft. 5in
Vertical Run Down = 5 ft.
Horizontal Run = (H1 + H2) = (10ft. + 20ft.) = 30 ft.
Number of Elbows = 2
Effective Length = Vertical Run Up + (2 x Vertical Run Down) +
Horizontal Run + (3 x # of 90° Elbows) + (1.5 x # of 45° Elbows)
Effective Length = 3ft. 5in + (2 x 5 ft.) + 30 ft. + (3 x 2 Elbows) +
(1.5 x 0 Elbows)
Effective Length = 49 ft. 5in
NOTICE: Once vent runs in downward direction it cannot
turn back upward.
Ensure the sidewall venting clearances are observed. If
venting system is installed below ground, we recommend
a window well with adequate and proper drainage to be
installed around the termination area.
EXAMPLE 2
V1 H1 H2 Elbows
5ft 10ft 20ft
Total
Effective
Length
2 49ft 5in
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