Lennox International Inc Gas Units Table Exhaust Pipe Termination Size Reduction

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.

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 31 through 39 show typical ter-

TABLE 8

EXHAUST PIPE TERMINATION SIZE REDUCTION

G61MP	Exhaust Pipe Size	Termination Pipe Size
MODEL
045, 070, −071	2", 2−1/2", 3" or 4"	1−1/2"
090, −091	2", 2−1/2", 3" or 4"	2"
110, −111	2−1/2", 3" or 4"	*2"
135	3" or 4"	*2"

*Approved 3" concentric termination kit terminates with 2−5/8" ID pipe.

minations.

1 − Exhaust and intake exits must be in same pressure zone. Do not exit one through the roof and one on the

Inches(mm)

3(76) MAX.

SIZE TERMINATION PIPE PER TABLE 8.

UNCONDITIONED

side. Also, do not exit the intake on one side and the exhaust on another side of the house or structure.

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.

3 − If necessary, install a field−provided reducer to adapt larger vent pipe size to termination pipe size.

4 − On roof terminations, the intake piping should termi- nate straight down using two 90° elbows (See figure

8" (203) MIN

12" (305) ABOVE AVERAGE SNOW ACCUMULATION

3" (76) OR 2" (51) PVC

PROVIDE SUPPORT

FOR INTAKE AND EXHAUST LINES

ATTIC SPACE

1/2" (13) FOAM INSULATION IN UNCONDITIONED SPACE

31).

5 − Exhaust piping must terminate straight out or up as shown. In rooftop applications, a reducer may be re- quired on the exhaust piping at the point where it exits the structure to improve the velocity of exhaust away from the intake piping. See table 8.

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

6 − On field supplied terminations for side wall exits, ex- haust piping should extend a minimum of 12 inches (305mm) beyond the outside wall. Intake piping should be as short as possible. See figure 32.

7 − On field supplied terminations, a minimum separation distance between the end of the exhaust pipe and the end of the intake pipe is 8 inches (203mm).

8 − If intake and exhaust piping must be run up a side wall to position above snow accumulation or other obstruc- tions, piping must be supported every 3 ft. (.9m) as shown in figure 22. Refer to figure 35 for proper piping method. In addition, WTK wall termination kit must be extended for use in this application. See figure 38. When exhaust and intake piping must be run up an outside wall, the exhaust piping is reduced to 1−1/2" (38mm) after the final elbow. The intake piping may be equipped with a 90° elbow turndown. Using turndown will add 5 feet (1.5m) to the equivalent length of the pipe.

9 − Based on the recommendation of the manufacturer, a multiple furnace installation may use a group of up to four termination kits WTK assembled together hori- zontally, as shown in figure 37.

DIRECT VENT ROOF TERMINATION KIT

(15F75 or 44J41)

FIGURE 31

	12" (305) MAX.
1/2" (13) ARMAFLEX	(unless supported)
INSULATION IN			1/2" (13)
UNCONDITIONED SPACE
		ARMAFLEX
		INSULATION
FIELD−			SIZE
PROVIDED
			TERMINA-
REDUCER MAY	6" (152)
			TION PIPE
BE REQUIRED	MAXI-
			PER TABLE
TO ADAPT	MUM
			8.
LARGER VENT
PIPE SIZE TO
TERMINATION
OUTSIDE	8" (203)		Inches (mm)
WALL
	MINIMUM
2" (51)
PVC
COUPLING
TOP VIEW WALL RING KIT WITH STRAIGHT INTAKE
	(15F74)
1/2 (13) ARMAFLEX	12 (305) MAX.
INSULATION IN
UNCONDITIONED			1/2" (13)
SPACE			ARMAFLEX
			INSULATION
FIELD−
PROVIDED
REDUCER MAY
BE REQUIRED
TO ADAPT			SIZE
LARGER VENT	6 (152)	TERMINATION PIPE
PIPE SIZE TO	MAXIMUM		PER TABLE 8.
TERMINATION
	4 (102)
Inches (mm) OUTSIDE	MINIMUM
WALL
TOP VIEW WALL RING KIT WITH 90° ELBOW ON INTAKE
	(15F74)

FIGURE 32

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