Lennox Hearth MPD-35 Series, MPD-45 Series Exterior Wall Thickness, Inches mm, Table F, Table G

HORIZONTAL VENT FIGURES/TABLES

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.

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.

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 (Se- cure Flex) firestop/spacer must be used anytime vent pipe passes through a combustible wall.

Note: An elbow is acceptable as 1 foot of vertical rise, except where an elbow is the only vertical component in the system. (See Figure 35 ).

WARNING: UNDER NO CIRCUMSTANCES MAY SEPA- RATE SECTIONS OF CONCENTRIC FLEXIBLE VENT PIPE BE JOINED TOGETHER.

H = 28 in. (711 mm) Maximum.
*When using Secure Flex,	H
use Firestop/Spacer
SF4.5HF

*Wall Firestop/Spacer

(SV4.5HF)

7 in. (178 mm)

TABLE 4

Venting Components Required for Various Exterior Wall

Thicknesses, When Using The Square Termination (SV4.5HT-2)

Venting Components Required	Exterior Wall Thickness
	inches (mm)
Termination Kit Only	6 to 9-1/4
	(152 to 235)
Termination Kit and 6 in. vent	10-3/4 to 14
section (SV4.5L6)	(273 to 356)
Termination Kit and12 in. vent	16-3/4 to 20
section (SV4.5L12)	(426 to 508)
Termination Kit and Telescopic	11-3/4 to 20
section (SV4.5LA) and 6 in. vent
	(299 to 508)
section (SV4.5L6)

Note: See Figure 33 for wall thickness range reductions when using SV4.5HT-2.

See Table 4 as an aid in venting component selection for a particular range of exterior wall thicknesses.

Figure 34 - Rear Vent - NO ELBOWS -

Square Horizontal Termination (SV4.5HT-2)

	TABLE F			Square termination
H Maximum		V Minimum
				(SV4.5HT-2) shown.
feet	(meters)	feet	(meters)
3	(0.914)	Elbow Only

TABLE G

H Maximum		V Minimum
feet	(meters)	feet	(meters)
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 = 40 feet (12.2 m) Max.

H = 20 ft. (6.096 m) 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.

H

V

	H
*When using Secure Flex,
use Firestop/Spacer	V
SF4.5VF

*When using Secure Flex,	*Wall
use Firestop/Spacer	Firestop/Spacer
SF4.5HF	(SV4.5HF)

See Table 4 as an aid in venting component selection for a particular range of exterior wall thicknesses.

Figure 35 - Top Vent -

ONE 90 DEGREE ELBOW - ELBOW CONNECTION AT APPLIANCE

*When using Secure Flex,	*Wall Firestop/Spacer
	(SV4.5HF)
use Firestop/Spacer
SF4.5HF	*Ceiling
	Firestop/Spacer
Square termination	(SV4.5VF)
(SV4.5HT-2) shown.

Figure 36 - Top Vent - ONE 90 DEGREE ELBOW -

ELBOW CONNECTION NOT DIRECTLY AT APPLIANCE

18

NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.