Lennox MPDT33RNM Installation Instructions Manual page 18

LENNOX HEARTH PRODUCTS • MERIT PLUS
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.
Note: Install the U-shaped vent restrictor in any vent run
with more than 8 ft of vertical rise (See Page 13).
Figure 30: 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)
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 36.
Note: Install the U-shaped vent restrictor in any vent run with
more than 8 ft of vertical rise (See Page 13).
Figure 31: 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.
DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
V1
V 1
H 1
H1
Ceiling
Firestop/Spacer
SV4.5VF*
*When using Secure Flex, use
Ceiling Firestop/Spacer SF4.5VF.
**When using Secure Flex, use
Wall
Wall Firestop/Spacer SF4.5HF.
Firestop/Spacer
SV4.5HF**
Ceiling
Firestop/Spacer
SV4.5VF*
V
H
Ceiling
Firestop/Spacer
SV4.5VF*
H
*When using Secure Flex, use
Ceiling Firestop/Spacer SF4.5VF.
**When using Secure Flex, use
Wall Firestop/Spacer SF4.5HF.
Wall
Firestop/Spacer
SV4.5HF**
V