Lennox International Inc ML193UH FIGURE Exiting Exhaust and Intake Vent, different pressure zones

Details of Intake and Exhaust Piping Terminations for Direct Vent Installations

NOTE - In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged to outdoors.

NOTE - Flue gas may be slightly acidic and may adversely affect some building materials. If any vent termination is used and the flue gasses may impinge on the building ma­ terial, a corrosion-resistant shield (minimum 24 inches square) should be used to protect the wall surface. If the optional tee is used, the protective shield is recommended.

TABLE 8

EXHAUST PIPE TERMINATION SIZE REDUCTION

ML193UH	Termination
MODEL	Pipe Size
*045 and 070	1-1/2” (38mm)
*090	2” (51mm)
110	2” (51mm)
135	2” (51mm)

*ML193UH-045, -070 and -090 units with the flush mount termination must use the 1-1/2” accelerator supplied with the kit unless a tee is used for termination as shown figure 42.

The shield should be constructed using wood, plastic, sheet metal or other suitable material. All seams, joints, cracks, etc. in the affected area should be sealed using an

Inches(mm)

3”(76mm) MAX.

SIZE TERMINATION PIPE PER TABLE 8.

UNCONDITIONED

appropriate sealant. See figure 42.

Intake and exhaust pipes may be routed either horizontally through an outside wall or vertically through the roof. In at­ tic or closet installations, vertical termination through the roof is preferred. Figures 35 through 43 show typical terminations.

8” (203mm) MIN

12” (305mm) ABOVE

AVERAGE SNOW

ACCUMULATION

ATTIC SPACE

1 - Intake and exhaust terminations are not required to be in the same pressure zone. You may exit the intake on one side of the structure and the exhaust on another side (figure 36). You may exit the exhaust out the roof and the intake out the side of the structure (figure 37).

NOTE - When venting in different pressure zones, maximum separation of intake and exhaust pipe DO NOT apply.

2 - Intake and exhaust pipes should be placed as close together as possible at termination end (refer to il­ lustrations). Maximum separation is 3” (76mm) on roof terminations and 6” (152mm) on side wall termina­ tions.

NOTE - When venting in different pressure zones, the maximum separation requirement of intake and ex­ haust pipe DOES NOT apply.

3 - On roof terminations, the intake piping should termi­ nate straight down using two 90° elbows (See figure 35).

4 - Exhaust piping must terminate straight out or up as shown. A reducer may be required on the exhaust pip­ ing at the point where it exits the structure to improve the velocity of exhaust away from the intake piping. See table 8.

5 - On field supplied terminations for side wall exit, ex­ haust piping may extend a maximum of 12 inches (305mm) for 2” PVC and 20 inches (508mm) for 3” (76mm) PVC beyond the outside wall. Intake piping should be as short as possible.

6 - On field supplied terminations, a minimum distance between the end of the exhaust pipe and the end of the intake pipe without a termination elbow is 8” and a minimum distance of 6” with a termination elbow.

NOTE - Care must be taken to avoid recirculation of exhaust back into intake pipe.

3” (76mm) OR

2” (51mm) PVC

PROVIDE SUPPORT

FOR INTAKE AND

EXHAUST LINES

DIRECT VENT ROOF TERMINATION KIT

(15F75 or 44J41)

FIGURE 35

Exiting Exhaust and Intake Vent

(different pressure zones)

Exhaust	Furnace	Inlet Air
		(Minimum 12 in.
Pipe
		305 MM) above
		grade or snow
		accumulation

FIGURE 36

Exiting Exhaust and Intake Vent

(different pressure zones)

Roof Terminated

Exhaust Pipe

Inlet Air

Furnace(Minimum 12 in. 305 MM) above grade or snow

accumulation

FIGURE 37

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