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NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
HORIZONTAL VENT FIGURES / TABLES (CONTINUED)
Table F
H
+ H
1
Maximum
V Minimum
feet (meter) feet (meter)
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)
H
+ H
1
= 20 feet (6.096 m) Max.
V + V
1
+ H + H
1
= 40 ft. (12.2 m) Max.
Typical termination shown.
LENNOXHEARTHPRODUCTS•MERIT
®
SERIESDIRECT-VENTCONTEMPORARYDESIGNGASFIREPLACES•MODELMLDVTCD-35•INSTALLATIONINSTRUCTIONS
Example: If 20 feet total (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 29.
V
H
H
1
V
1
Wall Firestop/Spacer
(SV4.5HF)
Ceiling
Firestop/Spacer
(SV4.5VF)
Whenusing Secure Flex,
use Firestop/Spacer
SF4.5VF.
When using Secure
Flex, use Firestop/Spacer
SF4.5HF.
Wall Firestop/Spacer
(SV4.5HF)
See Table 8 on Page 20 as
an aid in venting component
selection for a particular
range of exterior wall thick-
nesses.
Figure 32 - Top Vent - THREE 90 DEGREE ELBOWS