21
NOTE: DIAGRAMS & ILLUSTRATIONS ARE 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
TM
, use
Firestop/Spacer SF4.5VF.
Table E
H
+ H
1
Maximum
V Minimum
feet
(meter)
feet
(meter)
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
= 60 feet (18.3 m) Max.
H
+ H
1
= 20 ft. (6.096 m) Max.
Figure 33
-
Top Vent - TWO 90-DEGREE ELBOWS
LENNOX HEARTH PRODUCTS • MERIT
®
SERIES DIRECT-VENT GAS FIREPLACES • MODELS MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS
See Table 8 on Page 20 as an aid in venting
component selection for a particular range of
exterior wall thicknesses.
HORIZONTAL VENT FIGURES / TABLES
(continued)
Example: If 20 feet of (H + H
1
) 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+ H
1
) 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 31.
Typical termination shown.
