32
Table 5
Furnace
Model Number
*RC/*RL
Furnace
Input
(Btuh)
Cabinet
Width
(in.)
Nominal
Electrical
Supply
Maximum
Operating
Voltage
Minimum
Operating
Voltage
Maximum
Furnace
Amperes
Maximum
Fuse or Circuit
Breaker Amps**
054D-24B
54,000
17
½
115-60-1
127
103
10.0
15
072D-35C
72,000
21
115-60-1
127
103
9.3
15
090D-35C
90,000
21
115-60-1
127
103
15.6
20
108D-45D
108,000
24
½
115-60-1
127
103
15.6
20
Thermostat Wire Gauge
Recommended Thermostat Wire Length
2 - wire (Heating)
4 or 5 wire (Cooling)
24
55 ft.
25 ft.
22
90 ft.
45 ft.
20
140 ft.
70 ft.
18
225 ft.
110 ft.
** Time-delay fuses or HACR-type circuit breakers are required.
Table 5. Wire Length & Voltage Specifications
Figure 39
Figure 39.
Low Voltage Field, Four-wire
Heating / Cooling Applications
RC
YG
W
STATUS
FLAME
GREEN
RED
180
COOL
HEA
T
120
90
60
YELLOW
BLOWER
OFF
DELAY
LO
W
ML
MH
HIGH
EA
C
L1
XFMR
HUM
COM
SPEED
SELECT
3 AMP
FUSE
24V
5
NEUTRALS
ROOM
THERMOSTAT
A/C CONDENSING UNIT
CONDENSING UNIT
CONTROL BOX
EXPANSION PORT
(MOTOR CONNECTION)
FIELD WIRING
LOW VOLTAGE
CONNECTION
R
C
Y
G
W
NOTE: The “Y” terminal
on the control board
must be connected to the
thermostat
for
proper
cooling mode operation.
Connect
R & W
For Heating
Only
2
ELECTRONIC AIR CLEANER
MOTOR SPEED TAPS
(NOT USED)
HUMIDIFIER TAP
NEUTRAL LEADS
6
3
4
1
7
8
9
5
2
6
3
4
1
FA
N
Figure 40
Figure 40. Single Stage Twinning
TWIN TERMINAL
FURNACE 1
6-Pin Wiring
Harness
TWINNING
CONTROL
BOARD
FURNACE
BOARD
FURNACE 2
TWIN TERMINAL
TWINNING
CONTROL
BOARD
FURNACE
BOARD
Expansion Port
6-Pin Wiring
Harness
Expansion Port
Expansion Port
Expansion Port
W
G
Y
C
R
THERMOSTAT
W
G
Y
R
A/C
UNIT
W
G
Y
C
R
Figure 38
Field Supplied
Disconnect w/in
Sight of Furnace
Field Supplied
Panel Connector
Field Supplied
Fused Service
Panel
Black (Hot)
White (Neutral)
Green or Bare
(Ground)
Black
White
Black
White
Black
White
Field Line Voltage Wiring
Factory Line Voltage Wiring
Ground
Ground
Junction Box (may be int. or ext. to the furnace). These
connections can be made in the field supplied disconnect
at the furnace. NOTE: Connections made within the furnace
burner compartment do not require a junction box.
Ground
Figure 38. Line Voltage Field Wiring
Summary of Contents for M4RC-072D-35C
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