Lennox Hearth Direct Vent MPD-40 Series User Manual
Page 20
20
NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.
V
H
H1
V1
**Wall Firestop/Spacer
(SV4.5HF)
*Ceiling
Firestop/Spacer
(SV4.5VF)
*When using Secure Flex,
use Firestop/Spacer
SF4.5VF
**When using Secure
Flex, use Firestop/Spacer
SF4.5HF
**Wall Firestop/Spacer
(SV4.5HF)
V
H2
H1
H
**Wall Firestop/Spacer
(SV4.5HF)
*Ceiling
Firestop/Spacer
(SV4.5VF)
*When using Secure Flex,
use Firestop/Spacer
SF4.5VF
**When using Secure
Flex, use Firestop/Spacer
SF4.5HF
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 + H2 = 40 feet (12.2 m) Max.
H = 8 feet (2.438 meters) Max.
H + H1+ H2 = 20 feet (6.096 meters) Max.
H
+ H
1
+ H
2
Maximum
TABLE K
(meters)
(meters)
(meters)
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 maxi-
mum 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.
V Minimum
feet
feet
5
(1.524)
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)
(meters)
TABLE L
(meters)
H Maximum
1
1
H
+ H
1
= 20 feet (6.096 m) Max.
V
+ V +
H
+ H = 40 ft. (12.192 m) Max.
Figure 40
- Top Vent - THREE 90 DEGREE ELBOWS
Figure 39
- Rear Vent - THREE 90 DEGREE ELBOWS (Square termination SV4.5HT-2 shown.)
See
Table 4 on page 18 as an aid in venting component selection for a particular range of exterior wall thicknesses.
See
Table 4 on page 18 as an aid in venting component selection for a particular range
of exterior wall thicknesses.
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.
(Square termination
SV4.5HT-2 shown.)
HORIZONTAL VENT FIGURES/TABLES (continued)