Bulletin 30-034.009
Page 7
Copyright © 2022 Unico Inc.
circuit sizes to 60 amps. To combine one of the heater
circuits and the motor circuit similar to the 10kw, use
the 4-pole jumper bar included (Figure 12). Use an
optional 6-pole jumper bar (P/N: A01241-002 to
combine all the circuit breakers into one large circuit
(Figure 13).
Figure 12. Combined one heater circuit and motor
circuit with 4-pole jumper bar. (15 and 20 kW single
phase furnaces only) (Option 1)
Figure 13. Single power supply (15 and 20 kW single
phase furnaces only) (Option 2)
Blower control box mounting.
When using a
Unico
electric furnace, mount the blower control box on top of
the blower cabinet or to a remote location near the
blower module.
Control wiring.
The electric furnace is controlled with
24Vac control signals. The furnace has one, two, or
three stages (steps) of heat. These can be combined with
a jumper wire if desired. Refer to the blower motor
instructions for information on how to connect an
electric furnace to the blower motor control. The
method of connection will vary for different models of
blowers. Figures 14-16 are examples.
Figure 14. Control Wiring Diagram for Heating-
Only or Cooling/Heating Applications
1
2
3
4
5
6
7
W
Y
R
O
X
2
3
4
5
6
7
1
Y2
G
Y
RC
RH
OB
C
W2
W/E
UNICO P/N: A00915-G04
UNIVERSAL PROGRAMMABLE
AUTO CHANGE OVER DIGITAL
3 HEAT/2COOL THERMOSTAT
FAN INTERLOCK
DEFROST HEAT
STEP 1 (5 kW AND UP)
STEP 2 (7.5 kW AND UP)
STEP 3 (15 kW AND UP)
COMMON
POWER
COMMON
COMMON
REV. VALVE (HEAT/COOL)
COOL
POWER
FAN
UNICO SYSTEM
AIR HANDLER
OUTDOOR
CONDENSING
UNIT
WON ELECTRIC
DUCT HEATER
1
EL00004b.cvx
EMER. HEAT
AUX. HEAT
DEFROST HEAT
REV. VALVE
COMPRESSOR
1
1
L
6
TO REDUCE HEATING CAPACITY AND PREVENT SHORT CYCLING IN MILD
WEATHER, INSTALL AN OUTDOOR THERMOSTAT IN CIRCUIT.
CONTROL WIRING DIAGRAM FOR UNICO HEAT PUMP
WITH WON ELECTRIC DUCT HEATER
Figure 15. Control Wiring Diagram for Heat Pump
Applications
All furnaces below 20 kW are internally wired to
provide 5 kW of defrost heat. The 20 kW furnace
provides 10 kW of defrost heat. If 10 kW of heating
during defrost is desired for the smaller kW furnaces,
contact the Unico Engineering Office for instructions.
It is important to use a thermostat designed for use with
electric heat because a normal HEAT-COOL
thermostat will not energize the fan. Thermostats
designed for heat pump systems will also work.
Match thermostat anticipator settings for combined
amperage load of all components, including electric
furnace contactors, to prevent damage to thermostat.
The internal wiring diagrams are shown in Figures 18
through 22.
L1
L2
240V
L1
L2
Heater
Circuit
Breaker 2
Heater
Circuit
Breaker 1
M1
M2
240V
Motor
Circuit
Breaker
4-pole jumper bars included with furnace
IL00488a.cvx
L1
L2
L1
L2
Heater
Circuit
Breaker 2
Heater
Circuit
Breaker 1
M1
M2
240V
Motor
Circuit
Breaker
Requires 6-pole jumper bars
