19
C
IRCULATION
A
IR
F
ILTERS
Figure 11
Figure 12
Figure
13
Figure
14
Figure 15
One of the most common causes of a problem in a forced
air heating system is a blocked or dirty fi lter. Circulating air
fi lters must be inspected monthly for dirt accumulation and
replaced if necessary. Failure to maintain clean fi lters can
cause premature heat exchanger failure.
A new home may require more frequent replacement until all
construction dust and dirt is removed.
Upflow / Horizontal
Models
Minimum Recommended Filter Size^
*MEC80403B*
1 - 16 X 25 Side or 1 - 14 X 24 Bottom Return
*MEC80603B*
1 - 16 X 25 Side or 1 - 14 X 24 Bottom Return
*MEC80604B*
1 - 16 X 25 Side or 14 X 24 Bottom Return
*MEC80803B*
1 - 16 X 25 Side or Bottom Return
*MEC80804C*
1 - 16 X 25 Side or Bottom Return
*MEC80805C*¹
1 - 16 X 25 Side or Bottom Return¹
*MEC80805D*¹
1 - 16 X 25 Side or Bottom Return¹
*MEC81005C*
2 - 16 X 25 Side or 1 - 20 X 25 Bottom Return
*MEC81005C*
2 - 16 X 25 Side or 1 - 20 X 25 Bottom Return
Downflow / Horizontal
Models
*CEC80403B*
2 - 10 X 20 or 1 - 14 X 25 Top Return
*CEC80603B*
2 - 10 X 20 or 1 - 14 X 25 Top Return
*CEC80805C*
2 - 14 X 20 or 1 - 16 X 25 Top Return
*CEC81005C*
2 - 14 X 20 or 1 - 20 X 25 Top Return
¹ = use 2 - 16 X 25 filters and two side returns or 20 X 25
filter on bottom return if furnace is connected
to a cooling unit over 4 tons nominal capacity
^ Larger filters may be used, filters may also be centrally located
E
LECTRICAL
24 V
OLT
T
HERMOSTAT
W
IRING
W
IRE
ROUTING
MUST
NOT
INTERFERE
WITH
CIRCULATOR
BLOWER
OPERATION
,
FILTER
REMOVAL
OR
ROUTINE
MAINTENANCE
.
IMPORTANT NOTE
Low voltage connections can be made through either the right or
left side panel. Thermostat wiring entrance holes are located in
the blower compartment. The following fi gure shows connections
for a “heat/cool system”.
This furnace is equipped with a 40 VA transformer to facilitate
use with most cooling equipment. Consult the wiring diagram,
located on the blower compartment door, for further details of
115 Volt and 24 Volt wiring.
R
Y
C
Furnace
Integrated
Control
Module
Remote Condensing Unit
(Single-Stage Cooling)
R
Thermostat - Single -Stage Heating with Single-Stage Cooling
NOTE:
To apply a single-stage Heating Thermostat, the thermostat
selector switch on the Integrated Control Module must be set
on single-stage.
