Lennox International Inc G61MP specifications 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 20 through 28 show typical ter- minations.

1. Exhaust and intake exits must be in same pressure

zone. Do not exit one through the roof and one on the

side. Also, do not exit the intake on one side and the

exhaust on another side of the house or structure.

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 26.

TABLE 14

EXHAUST PIPE TERMINATION SIZE REDUCTION

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

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

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-

Inches(mm)

3(76) MAX.

SIZE TERMINATION PIPE PER TABLE 14.

UNCONDITIONED

	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
	20).
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 14.

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

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

DIRECT VENT ROOF TERMINATION KIT

(15F75 or 44J41)

FIGURE 20

should be as short as possible. See figure 21.

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 12. Refer to figure 24 for proper piping

method. In addition, WTK wall termination kit must be

extended for use in this application. See figure 27.

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

1/2" (13) ARMAFLEX

INSULATION IN

UNCONDITIONED SPACE

FIELD−

PROVIDED

REDUCER MAY

BE REQUIRED

TO ADAPT

LARGER VENT

PIPE SIZE TO

TERMINATION

OUTSIDE

WALL

2" (51) PVC COUPLING

12" (305) MAX.

(unless supported)

1/2" (13)

ARMAFLEX INSULATION

SIZE TERMINATION

PIPE PER

6" (152) TABLE 14. MAXIMUM

8" (203)

MINIMUM

Inches (mm)

equipped with a 90° elbow turndown. Using turndown

will add 5 feet (1.5m) to the equivalent length of the

pipe.

TOP VIEW WALL RING KIT

(15F74)

FIGURE 21

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