Lennox MPDT33RNM Installation Instructions Manual page 22

LENNOX HEARTH PRODUCTS • MERIT PLUS
HORIZONTAL VENT FIGURES/TABLES (continued)
H 2
*When using Secure Flex , use
Ceiling Firestop/Spacer SF4.5VF.
**When using Secure Flex, use
Wall Firestop/Spacer SF4.5HF.
Square termination
(SV4.5HT-2) shown.
See Table 9 on Page 21 as
an aid in venting component
selection for a particular range
of exterior wall thicknesses.
NOTE: Install the U-shaped vent
restrictor in any vent run with
more than 8 ft of vertical rise
(See Page 13).
Figure 40 - Rear Vent - THREE 90-DEGREE ELBOWS
H 1
Wall Firestop/Spacer
SV4.5HF**
Square termination (SV4.5HT-2) shown.
See Table 9 on Page 21 as an aid in venting component selection for a particular range of
exterior wall thicknesses.
NOTE: Install the U-shaped vent restrictor in any vent run with more than 8 ft of vertical rise
(See Page 13).
Figure 41 - Top Vent - THREE 90-DEGREE ELBOWS
22
DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
®
Wall Firestop/Spacer
SV4.5HF**
H 1
®
Ceiling
Firestop/Spacer
SV4.5VF*
V
*When using Secure Flex, use
Ceiling Firestop/Spacer SF4.5VF.
**When using Secure Flex, use
Wall Firestop/Spacer SF4.5HF.
V 1
Wall Firestop/Spacer
SV4.5HF**
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
H
+ H
1
feet
5
10
15
20
H
Ceiling
Firestop/Spacer
SV4.5VF*
H
TABLE K
Maximum
+ H
H Maximum
2
feet
(meters) (meters)
(1.524) 2 (0.610)
(3.048) 4 (1.219)
(4.572)
6 (1.829)
(6.096) 8 (2.438)
V + H + H 1 + H 2 = 40 feet (12.2 m) Max.
H = 8 feet (2.438 meters) Max.
H + H 1 + H 2 = 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.
TABLE L
H Maximum
(meters)
feet
(1.524)
5
5 (1.524)
10 (3.048)
15 (4.572)
20 (6.096)
H + H = 20 feet (6.096 m) Max.
1
V H
+ V + + H = 40 ft. (12.192 m) Max.
1 1
Example: If 20 feet of (H) horizontal vent
V
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.
V Minimum
feet (meters)
1 (0.305)
2 (0.610)
3 (0.914)
4 (1.219)
V Minimum
(meters)
feet
Elbow Only
(0.305)
1
(0.610)
2
(0.914)
3
(1.219)
4