Lennox Hearth Direct Vent MPD-40 Series User Manual
Page 19
19
NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.
V
H
H1
*Wall Firestop/Spacer
(SV4.5HF)
*Wall Firestop/Spacer
(SV4.5HF)
*When using Secure Flex,
use Firestop/Spacer
SF4.5HF
**Ceiling
Firestop/Spacer
(SV4.5VF)
**Note - When using
Secure Flex, use
Firestop/Spacer SF4.5VF
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.
See
Table 4 on page 18 as an aid in venting component
selection for a particular range of exterior wall thicknesses.
TABLE H
H
+H
1
Maximum
H Maximum
V Minimum
feet
feet
feet
5
(1.524)
2
(0.610)
1
(0.305)
10
(3.048)
4
(1.219)
2
(0.610)
15
(4.572)
6
(1.829)
3
(0.914)
20
(6.096)
8
(2.438)
4
(1.219)
V + H + H1 = 40 feet (12.2 m) Max.
H = 8 feet (2.438 meters) Max.
H + H1 = 20 feet (6.096 meters) Max.
(meters)
(meters)
(meters)
H1
V
H
*Wall
Firestop/Spacer
(SV4.5HF)
**Ceiling
Firestop/Spacer
(SV4.5VF)
*When using
Secure Flex, use
Firestop/Spacer
SF4.5HF
**When using
Secure Flex, use
Firestop/Spacer
SF4.5VF
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.
An elbow is acceptable as 1 foot of vertical rise except where an elbow is the only vertical component in the system. See Figure 35.
Figure 37
- Rear Vent - TWO 90 DEGREE ELBOWS
(Square termination SV4.5HT-2 shown.)
Figure 38
- Top Vent - TWO 90 DEGREE ELBOWS
(Square termination SV4.5HT-2 shown.)
H
+ H
1
Maximum
V Minimum
feet
feet
3
(0.914)
Elbow Only
5
(1.524)
1
(0.305)
10
(3.048)
2
(0.610)
15
(4.572)
3
(0.914)
20
(6.096)
4
(1.219)
V +
H
+ H
1
= 40 feet (12.2 m) Max.
H
+ H
1
= 20 ft. (6.096 m) Max.
TABLE J
(meters)
(meters)
HORIZONTAL VENT FIGURES/TABLES (continued)
See
Table 4 on page 18 as an aid in venting component selection for a particular range of exterior wall thicknesses.