CONTROL WIRING
LINE VOLTAGE IS PRESENT ON SOME OF THE TERMINALS
ON THE CONTROL TERMINAL BOARD. ALWAYS DISCON-
NECT THE POWER FROM THE HEATER BEFORE MAK-
ING ANY CONNECTIONS TO THE CONTROL BOARD TO
PREVENT ELECTRIC SHOCK HAZARD.
MT-1
MT-2
2-STAGE
INTERNAL
THERMOSTAT
BLACK
RED
RED
BLACK
P2
H2
F 1
F 2
S
REMOTE SUMMER
FAN SWITCH (MRFS-1)
OR SUMMER FAN
SWITCH MCFS (MANUAL)
P1
H1
Figure 4. Control Terminal Board
(for Heaters Without Contactors)
NOTES:
1. THIS STYLE CONTROL TERMINAL BOARD
USED WITH MODELS MUH0321, MUH0371,
MUH0381, MUH0521, MUH0571, AND
MUH0581.
2. WHEN UNIT IS WIRED FOR SINGLE-PHASE,
JUMPER H1 TO H2. IF SINGLE-POLE THER-
MOSTAT IS USED WITH SINGLE-PHASE
UNIT, CONNECT THERMOSTAT LEADS TO
P1 AND H1.
3. EXTERNAL LINE VOLTAGE THERMOSTATS
SHOULD BE TREATED AS SINGLE STAGE
ONLY.
5
!
WARNING
1.
Use min. 600 volts, NEC Class 1 insulated wire for all
control circuit wiring.
2.
Use a crimp-on type fork terminal on the wire ends that
attach to the control terminal board if more than one
connection is to be made under the terminal screw.
3.
On units not provided with internal contactor (3 & 5 KW),
refer to Figure 4 for wiring diagram.
Note:
Thermostat and control circuit wiring must be suit-
able to handle the full load of the heater (example
MUH0581 is rated 24 amps)
4.
On units provided with internal contactor (units rated 7
KW and higher) refer to Figure 5 for wiring diagram.
Control wiring must be rated minimum 18 AWG.
B
3 PHASE BLOCK
FACTORY-WIRED FOR SINGLE-PHASE POWER
C1
D
1
D
1
C1
C
D
B
C
D
3 PHASE BLOCK
B
3 PHASE BLOCK
FIELD-WIRED FOR THREE-PHASE POWER
C1
D
1
D
1
C1
C
D
B
C
D
3 PHASE BLOCK
Figure 3b. Wiring Connections for Single-Phase and Three -Phase Power (MUH158)
