Lennox International Inc Lennox Merit Series Gas Furnace Upflow/Horizontal Air Discharge, ML193UH

CONDENSATE	Optional Return Air Base
	(Upflow Applications Only)
TRAP

AIR FLOW

17−1/2 (446) B Width (50W98)

21 (533) C Width (50W99) 24−1/2 (622) D Width (51W00)

FRONT VIEW

FURNACE

FRONT

INDOOR AIR

QUALITY

CABINET

(PCO, Filter

Cabinet, etc.)

OPTIONAL RETURN AIR BASE

IF BASE	3−1/4			1 23 (584)
IS USED				Overall
	(83)				1
WITHOUT				(Maximum)		Minimum
IAQ CABINET,						11 (279)
A SINGLE		1 Unit side return air			2 Maximum		1	22−7/16
RETURN AIR						14 (356)
								(570)
PLENUM			Opening
								Overall
MUST
							(Maximum)
COVER BOTH
UNIT AND				SIDE RETURN
RETURN	7−1/4	5−5/8
AIR BASE				AIR OPENINGS
		(143)
OPENINGS	(184)
				(Either Side)
				23				3/4
				(584)
				26−7/8				(19)
				(683)

SIDE VIEW

NOTE- Optional side return air filter kits are not for use with return air base.

1Both the unit return air opening and the base return air opening must be covered by a single plenum or IAQ cabinet.

Minimum unit side return air opening dimensions for units requiring 1800 cfm of air and over (W x H): 23 x 11 in. (584 x 279 mm). The opening can be cut as needed to accommodate plenum or IAQ cabinet while maintaining dimensions shown.

Side return air openings must be cut in the field. There are cutting guides stenciled on the cabinet for the side return air

opening. The size of the opening must not extend beyond the markings on the furnace cabinet.

2To minimize pressure drop, the largest opening height possible (up to 14 inches) is preferred.

FIGURE 14

Removing the Bottom Panel

Screw

Bottom Cap

Bottom Panel

FIGURE 15

Removing the Bottom Panel

Remove the two screws that secure the bottom cap to the furnace. Pivot the bottom cap down to release the bottom panel. Once the bottom panel has been removed, reinstall the bottom cap. See figure 15.

Horizontal Applications

WARNING

Do not install the furnace on its front or back. See figure 16.

FrontBack

FIGURE 16

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