Lennox Hearth Products MPDT-3328CPM-B Installation Instructions Manual page 18

VERTICAL VENT FIGURES/TABLES
(continued)
H Maximum
+H
1
(meters)
feet
(1.524)
5
(3.048)
10
(4.572)
15
(6.096)
20
V + V 1 + H + H 1 = 40 feet (12.2 m) Max
H = 8 feet (2.438 meters) Max.
H + H 1 = 20 feet (6.096 meters) Max.
Example: If 20 feet of (H) horizontal vent run is needed,
then 4 feet minimum of (V) vertical vent will be required.
This table shows a 1 (V) to 5 (H) ratio. For every 1 foot of
(V) vertical, you are allowed 5 feet of (H) horizontal run, up
to a maximum horizontal run of 20 feet.
Figure 33 - Rear Vent - THREE ELBOWS
TABLE D
H + Maximum
H
1
(meters)
feet
(1.524)
5
(1.524)
5
(3.048)
10
(4.572)
15
(6.096)
20
H + H = 20 feet (6.096 m) Max.
1
V + V + H + H
1 1
Example: If 20 feet of (H) horizontal vent run is needed, then 4 feet
minimum of (V) vertical vent will be required.
This table shows a 1 (V) to 5 (H) ratio. For every 1 foot of (V) verti-
cal, you are allowed 5 feet of (H) horizontal run, up to a maximum
horizontal run of 20 feet.
An elbow is acceptable as 1 foot of vertical rise except where an
elbow is the only vertical component in the system. See Figure 39.
Figure 34 - Top Vent - THREE ELBOWS
18
TABLE C
H Maximum V Minimum
(meters) (meters)
feet feet
(0.610) (0.305)
2 1
(1.219) (0.610)
4 2
(1.829) (0.914)
6 3
(2.438) (1.219)
8 4
V Minimum
(meters)
feet
Elbow Only
(0.305)
1
(0.610)
2
(0.914)
3
(1.219)
4
= 40 ft. (12.192 m) Max.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
H1
*Ceiling
Firestop/Spacer
(SV4.5VF)
**Wall
Firestop/Spacer
(SV4.5HF)
V1
V
*Ceiling
Firestop/Spacer
V 1
(SV4.5VF)
H
H 1
*Ceiling
Firestop/Spacer
(SV4.5VF)
H
**Wall
Firestop/Spacer
(SV4.5HF)
V