Furnace Used In Conjunction With Air Conditioning; Air Filter; Ductwork - ECR International A Series Installation, Operation And Maintenance Manual

6. Furnace Used In Conjunction With Air
Conditioning
• Install furnace in parallel with or upstream from evaporator
coil to avoid condensation in heat exchanger.
• When installed in parallel, prevent chilled air from entering
furnace by use of dampers or other air controlling means.
• Manually operated dampers must have a control to prevent
operation of either system unless dampers are in full heat or
full cool position.
• Air heated by the furnace shall not pass through evaporator
coil unless coil is specifically approved for such service.
• Check and adjust blower speed to compensate for pressure
drop caused by evaporator coil.
• Maintain required clearance between bottom of coil drain pan
and top of heat exchanger as specified by coil manufacturer.
• Cased evaporator coils with cases that are slightly larger
than the furnace cabinet may be used by employing field
fabricated block off plates to close gap between furnace
cabinet and coil casing. See Figures 2a and 2b.
• Cased evaporator coils with cases that are smaller than
the furnace cabinet should not be used as they will restrict
airflow.

7. Air Filter

• Install properly sized air filter on return air side of unit.
• Furnace is supplied with 16" x 20" permanent air filter and
filter frame.
• If filter is damaged, replace with filter of same size and type.

8. Ductwork

• Supply and return air ductwork must be designed and
installed in accordance with approved methods, local and
national codes as well as good trade practices.
• When ductwork supplies air to space other than where
furnace is located, return air must be sealed and directed to
this space.
• Return air may enter furnace through the right or left side
panels or the base panel. Cut out the appropriate 14" x 18"
return air opening accordingly. On side panel, remove four
(4) 3/4" button plugs to expose 3/4" round holes which
define 14" x 18" opening. The base panel has 3/4" square
knockouts to define the 14" x 18" return air opening. Take
care not to damage wires inside while cutting the opening.
• Mount the furnished filter frame and filter frame end support
on the return air opening. See Figure 3.
• Connect return air ductwork to filter frame.
• Use of an appropriately sized prefabricated return air boot
( sometimes referred to as a Buffalo boot) equipped with a
16" x 20" filter slot may be used as an option. In this case
use the furnished filter frame and filter frame end closer as
a transition piece to connect the return air boot to furnace's
return air opening. See Figures 4a and 4b.
• Manufacturer recommends installing blower door before
handling or moving the unit.
FIGURE 2a: Evaporator Coil
FIGURE 2b: Evaporator Coil Centered Over
Narrow Furnace
6
Block-Off Plates
PN 240010964 Rev. L [10/01/2021]