4
CIRCULATING AIR REQUIREMENTS
WARNING:
All return ducts must be secured to the Appliance
with sheet metal screws. All return ducts must be
adequately sealed. When return air is provided
through the bottom of the unit, the joint between
the Appliance and the return air plenum must
be air tight.
Return air and circulating air ducts must not be
connected to any other heat producing device
such as a fireplace insert, stove, etc. This may
result in fire, explosion, carbon monoxide
poisoning, personal injury, or property damage.
Return Air Connections
Air return to the Appliance must have a minimum free area
opening that meets the minimum installation clearances
found on page 5. A return air grille for closet or alcove
installations is available. Acceptable installations with
return air entering through an opening in the floor, ceiling
of a closet, or alcove installation, must meet all of the
following requirements:
• The return air opening, regardless of its location, must
not be smaller than size specified on unit data label. If
located in the floor, the opening must be provided with
a means of preventing its inadvertent closure by flat
object(s) placed over the opening.
• A return air grille must be used on the Appliance when
installed in a closet or alcove:
Upflow Alcove installations
– E7EM Models: Use a coil box with a solid door and an
upflow stand (Figure 1 (page 5)). Part numbers
can be found in the Technical Specifications
Literature.
– E7EU Models: Use upflow stand.
Closet installations
– All E7 Models: A louvered door must be added in
the closet door or above it for adequate air flow.
Downflow alcove installations
– E7EM Models: A grille may be attached to the top
of the Appliance and all paneling and trim flushed
to it. This installation provides an access door for
future installation of air conditioning or heat pump
coils on top of the Appliance.
– E7ED models are for non-ducted return.
– E7EU Models can be used for ducted return.
• Materials located in return air duct system must have
a flame-spread classification of 200 or less.
• Noncombustible pans having 1” (25 mm) upturned
flanges must be located beneath openings in a floor-
return duct system.
Supply Air Connections
• Supply duct system must be designed for proper
air distribution. Static pressure measured externally
to Appliance shall not exceed static pressure rating
listed on Appliance nameplate.
• Duct system must be designed so that no supply
registers are located in duct system directly below the
Appliance.
Filtering Methods - Downflow Appliances
Non-Ducted Return Air
For unducted return air systems, either the optional grille
and frame assembly or the optional wall mount grille is
recommended.
• E7ED Models: Make sure there is an 18” (457 mm) x
20” (508 mm) filter in the top filter rack and an 18” (457
mm) x 20” (508 mm) filter in the front filter rack.
Without A/C or H/P uncased coil
• Use the filter supplied with the Appliance. Make sure
the filter is installed mat side down between the filter
retainer and Appliance top.
With A/C or H/P uncased coil
• Use the optional coil filters; the filter supplied with
the Appliance is not used; REMOVE AND DISCARD
THIS FILTER.
With optional coil housing
• See coil cabinet instructions for specific filtering
methods.
Ducted Return Air
For ducted return air systems with air conditioners or
heat pumps, either providing an access panel in the duct
or using the optional coil cabinet is recommended. The
duct system must be properly sized to account for any
additional external static pressure produced from the
chosen filtering method.
NOTE: Install a filter with a minimum unrestricted medium
area that meets the application requirements of the
Appliance in the duct above the coil that is accessible for
monthly cleaning or replacement by homeowner.
Filtering Methods - Upflow Appliances
Non-Ducted Return Air
Appliances may be installed with unducted or ducted
return air. For unducted systems it is recommended to
use an upflow stand for optimal performance.
• For closet installations with less than 6” front clearance,
but not less than 1” (25 mm), a louvered door must
be used having a minimum 250 sq in2 (1,613 cm2)
free area opening directly in line with openings in the
Appliance door.
Clearances to Combustible Materials
• This Appliance is Design Certified in the U.S. and
Canada by ETL for the minimum clearances to
combustible materials. NOTE: The Appliance is listed
for installation on combustible or non-combustible
flooring. To obtain specific clearance information,
refer to the Appliance rating plate, located inside of
the Appliance cabinet.
• 0” from all surfaces of Appliance cabinet, ducts,
optional coil housing and plenum connector. No
separate subbase required for installations on
combustible flooring.
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