Lennox Hearth MPDR-3328CNE-B User Manual

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

LENNOX HEARTH PRODUCTS • MERIT

PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS

H Maximum

V Minimum

feet

(1.524)

(0.305)

(3.048)

(0.610)

(4.572)

(0.914)

(6.096)

(1.219)

V + H = 40 feet (12.2 m) Max.

H = 20 ft. (6.096 m) Max.

TABLE G

(meters)

TABLE F

H Maximum

V Minimum

feet

(0.914)

Elbow Only

(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 maximum horizontal

run of 20 feet.

Figure 39: Top Vent - ONE 90-DEGREE ELBOW -
ELBOW CONNECTION AT APPLIANCE

Figure 40: Top Vent - ONE 90-DEGREE ELBOW -
ELBOW CONNECTION NOT DIRECTLY AT APPLIANCE

See Table 3 as an aid in venting component selection

for a particular range of exterior wall thicknesses.

See Table 8 as an aid in venting component selection

for a particular range of exterior wall thicknesses.

Square termination (SV4.5HT-2) shown.

Venting Components Required for Various Exterior Wall Thick-

nesses, when using Typical Termination Kits

Vent Components Required Exterior Wall Thickness - inches (mm)
Termination Kit Only

6 to 9-1/4 (152 to 235)

Termination Kit and 6 In. Vent

Section (SV4.5L6)

10-3/4 to 14 (273 to 356)

Termination Kit and 12 in.

Vent Section (SV4.5L12)

16-3/4 to 20 (426 to 508)

Termination Kit and Tele-

scopic Section (SV4.5L12)

11-3/4 to 20 (299 to 508)

Table 8

Note: See Figure 37 showing wall thickness range

when using SV4.5HT-2 termination kit.

Only the square termination (SV4.5HT-2) may be used.

HORIZONTAL VENT FIGURES/TABLES

Note: Two 45 degree elbows may be used in place of one 90 degree

elbow. The same rise to run ratios, as shown in the venting figures for

90 elbows, must be followed if 45 degree elbows are used.

Note: It is very important that the horizontal/inclined run be maintained

in a straight (no dips) and recommended to be in a slightly elevated

plane, in a direction away from the fireplace of 1/4" rise per foot (20

mm per meter) which is ideal, though rise per foot run ratios that are

smaller are acceptable all the way down to at or near level.

See Table 8 as an aid in venting component selection

for a particular range of exterior wall thicknesses.

Note: SV4.5VF (Secure Vent), SF4.5VF (Secure Flex) firestop/spacer must

be used anytime vent pipe passes through a combustible floor or ceiling.

SV4.5HF (Secure Vent), SF4.5HF (Secure Flex) firestop/spacer must be

used anytime vent pipe passes through a combustible wall.

Note: Secure Vent components (rigid vent pipe and terminal) are

shown in the figures; Secure Flex components (flexible vent pipe and

terminal) may also be used.

Figure 38: Rear Vent - NO ELBOWS

WARNING

Under no circumstances, may separate sections of

concentric flexible vent pipe be joined together.

H = 28 in. (711 mm) Maximum.

7 in

(178 mm)

Wall Firestop/

Spacer

SV4.5HF**

**When using Secure Flex, use

Wall Firestop/Spacer SF4.5HF.

Ceiling

Firestop/

Spacer

SV4.5VF*

Wall Firestop/

Spacer SV4.5HF**

*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**

**When using Secure

Flex, use Wall Firestop/

Spacer SF4.5HF.