MG3P Installation Manual

31
FURNACE
MODEL
NUMBER
FURNACE
INPUT
(BTUH)
CABINET
WIDTH
(IN.)
NOMINAL
ELECTRICAL
SUPPLY
MAXIMUM
OPERATING
VOLTAGE
MINIMUM
OPERATING
VOLTAGE
MAXIMUM
FURNACE
AMPERES
MG3P-054U1AAB1 54,000 17 ½ 115-60-1 127 103 9.3
MG3P-072U1AAC1 72,000 21 115-60-1 127 103 9.3
MG3P-090U1AAC1 90,000 21 115-60-1 127 103 12
MG3S-080T2AAC1 80,000 21 115-60-1 127 103 8.7
MG3P-108U1AAD1 120,000 24 1/2 115-60-1 127 103 12
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.
Table 5. Wire Length & Voltage Specifications
Figure 42. Low Voltage Field, Four-wire
Heating / Cooling Applications
RCYGW
STATUS
FLAME
GREEN
RED
180
COOL
HEAT
120
90
60
YELLOW
BLOWER
OFF
DELAY
LOW
ML
MH
HIGH
EAC
L1
XFMR
HUM
COM
SPEED
SELECT
3 AMP
FUSE
24V
5
NEUTRALS
ROOM
THERMOSTAT
A/C CONDENSING UNIT
CONDENSING UNIT
CONTROL BOX
FIELD WIRING
LOW VOLTAGE
CONNECTION
R
C
Y
G
W
NO
TE: The “Y” terminal
on
the control board
m
ust be connected to the
thermostat
for proper
cooling mode operation.
Connect
R & W
For Heating
Only
2
ELECTRONIC AIR CLEANER
MOTOR SPEED T
APS
HUMIDIFIER TA P
NEUTRAL LEADS
6 3
4
1
7
8
9
5
2
63
4
1
FAN
L1A
Figure 43. 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
THERMOS
TAT
WG
YR
A/C
UNIT
W
G
Y
C
R
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
Ground
Junction box may be interior or exterior to the furnace,
but must be installed such that it is inaccessible without
tools. 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 bo
x.
Figure 41. Line Voltage Field Wiring