Non-Ducted Return Closet Installation
The air handler can be installed in a closet with a false bottom to
form a return air plenum or be installed with a return air plenum
under the air handler.
Louvers or return air grilles are field supplied. Local codes may
limit application of systems without a ducted return to single-
For a unit installed in a closet with a louvered return opening,
the minimum open area for the louvers will be as shown
18" and 24" models
30" and 36" models
42", 48" and 60" models
If the free area is not known, assume a 25% free area for
wood or a 75% free area for metal louvers or grilles.
Using the louver dimensions and the 25% or 75%
assumption, determine if the louver open area meets the
minimum open area listed above.
If the return air plenum is used, the return air grille should be
immediately in front of the opening in the plenum to allow for
the free flow of return air.
When not installed in front of the opening, there must be
adequate clearance around the air handler to allow for the
free flow of return air.
For ease in installation, it is best to make any necessary coil
configuration changes before setting air handler in place. See
"Installation Configuration Options."
Upflow air discharge only contains 1 drain pan.
Upflow or horizontal airflow contains 2 drain pans.
The air handler must be supported on the bottom only and set on
a field-supplied supporting frame with an air return opening.
Securely attach the air handler to the supporting frame.
Horizontal installations can be left-hand or right-hand air supply.
Adequate support must be provided to ensure cabinet integrity.
Ensure that there is adequate room to remove, service and
access panels if installing in the horizontal position. For correct
horizontal coil installation, see "Installation Configuration
Options" later in this section.
This coil is provided with a secondary drain that should be
trapped and piped to a location that will give the occupant a
visual warning that the primary drain is clogged. See "Install
When an evaporator coil is installed in an attic or above a
finished ceiling, an auxiliary drain pan should be provided
under the air handler as specified by most local building
320 sq. in.
360 sq. in.
450 sq. in.
Conversion from Vertical to Horizontal
An upflow only air handler may be converted to horizontal air
discharge by installing a horizontal drain pan kit. See
An upflow/horizontal air handler may be converted from
horizontal left-hand discharge to horizontal right-hand discharge
without additional parts.
Suspended Cabinet Installation
NOTE: Air handlers cannot be installed horizontally lying on or
suspended from either the front or back of the air handler. It must
be positioned with one side parallel to the floor when in the
The suspending means must be field fabricated, and should
consist of 2 "cradles" made by attaching 2 rods to a length of
angle iron or suitable gauge steel.
Installation Configuration Options
Shading indicates proper line connections
As shipped from the factory
(return in bottom)
A. Horizontal drain connections
(left or right hand)
Left to Right Airflow: Requires drain pan
A. Drain connections
B. Upflow drain connections
C. Bottom/filter frame