Lennox ML180UHA Installation Instructions Manual page 8

Upflow Applications
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or al­
cove installations are shown in figure 6.
Upflow Application Installation Clearances
Left Side
Bottom
Type of Vent
Connector
Top 25 mm (in.)
*Front 57 mm (2-1/4 in)**
Back
Sides
Vent 152 mm (6 in.)
Floor
*Front clearance in alcove installation must be 610 mm (24 in.).
Maintain a minimum of 610 (24 in.) mm for front service access.
** 114 mm (4-1/2 in.) if single wall vent pipe is used.
‡For installation on a combustible floor, do not install the furnace
directly on carpeting, tile or other combustible materials other
than wood flooring.
†Left side requires 76 mm (3 in.) if a single wall vent is used on 368
mm (14-1/2 in.) cabinets, or 51 mm (2 in.) if a single wall vent pipe
is used on 445 mm (17-1/2 in.) cabinets.
FIGURE 6
Return Air - Upflow Applications
Return air can be brought in through the bottom or either
side of the furnace installed in an upflow application. If the
furnace is installed on a platform with bottom return, make
an airtight seal between the bottom of the furnace and the
platform to ensure that the furnace operates properly and
Top
Right Side
Type C Type B1
25 mm (1 in.)
57 mm (2-1/4 in.)
0 0
0† 0
25 mm (1 in.)
0‡ 0‡
safely. The furnace is equipped with a removable bottom
panel to facilitate installation.
Markings are provided on both sides of the furnace cabinet
for installations that require side return air. Cut the furnace
cabinet at the maximum dimensions shown on page 2.
NOTE -
60C and 60D units that require air volumes over 850
L/s (1800cfm) must have one of the following:
1 - Single side return air with transition to accommodate
508 x 635 x 25 mm (20 x 25 x 1 in.) cleanable air filter. (Re­
quired to maintain proper air velocity.) See figure 7.
2 - Single side return air with optional return airbase. See fig­
ure 8.
3 - Bottom return air.
4 - Return air from both sides.
5 - Bottom and one side return air.
Refer to Product Specifications bulletin for additional informa­
tion.
Single Side Return Air
(with transition and filter)
AIR FLOW
Page 8
508mm X 635mm X 25mm
(20" X 25" X 1")
Cleanable Filter
Return Air
Plenum
Transition
FIGURE 7