Nordic ATWC Series, Installation And Service Manual, Page: 12 / 106

PRELIMINARY: 24-Sep-2021 Page 12 002536MAN-00
Wiring
IMPORTANT NOTE: A properly qualified
electrician should be retained for all
connections to the heat pump and associat-
ed controls. The connections to the unit
MUST CONFORM TO LOCAL CODES.
TABLE 3 - Power Supply Connections
Line Description Voltages
L1 Line 1 All
L2 Line 2 All
L3 Line 3 3-phase only
N Neutral
For 208/230-1-60, 208-3-60:
only required if connecting 115v
circulators.
Required for 460-3-60, 380-3-50.
GND Ground All (connect to ground lug)
Indoor Unit Power Supply Connections
Power supply for the heat pump from the breaker panel is
supplied to the indoor unit. The unit has a concentric power
supply knockouts, as well as knockouts and holes for connec-
tions to circulation pumps, controls, optional aquastat, and pow-
er and signal connections to the outdoor unit. All wiring is con-
nected to the indoor unit at the top rear, and fed to the front
electrical box through a wire channel under the top.
A schematic diagram (SCH) and electrical box layout
diagram (ELB) can be found on the electrical box cover of the
unit as well as in the Model Specific Information section of this
manual.
The Electrical Tables in the Model Specific Information
section contain information about the wire and breaker size.
Indoor Loop Circulator Pump Wiring
The indoor unit has provisions for connecting the indoor
circulator pump (between the heat pump and buffer/DHW tank)
so that it will be turned on whenever the compressor(s) operate.
Connect the circulator pump module to the appropriate terminals
( 115V or 230V ) on the terminal strip marked Indoor Circulator
Pumps , as per the voltage of the circulator pump. Ground
wires should be connected to the ground lug in the electrical
box. Ensure that the total current draw does not exceed the
value indicated on the label in the heat pump electrical box.
For 460VAC models , only 277VAC circulators may be
powered directly from the heat pump. If other voltage circulators
are used, they must be powered using an external contactor
actuated by the ICR terminal on the left side of the control board
and the C (24V ground) terminal.
TABLE 4 - Outdoor Unit Power Supply Connections
Line Description
L1 Supply line
L2 Supply line
GND Ground
Use a 2-conductor outdoor rated 14ga cable.
IMPORTANT NOTE: Most codes require a
disconnect switch visible and/or reachable
from the outdoor unit to be installed in the
power supply cable. If the switch has fuses
or breakers they must be no more than 10A.
Outdoor Unit: Power Connections
The ACEC outdoor unit must be powered from the indoor
unit. The power supply for the ACEC-45/55 unit is 208-277VAC,
50/60Hz, and for ACEC-65 to100 is 208/230-1-60. The ATWC
and ACEC units have matching terminal strips for these connec-
tions. Use a two conductor, minimum 14ga outdoor rated cable
for this connection. Refer to diagram.
Control Transformer
The low voltage controls, including the control board, are
powered by a 100VA class II transformer. 208/230-1-60 and
208-3-60 models have a resettable breaker on the secondary
side for circuit protection. Should the breaker trip, locate and
correct the problem and then reset the breaker by pressing it.
All other voltage models have primary and secondary fus-
es for circuit protection.
IMPORTANT NOTE: For 208/230VAC-1-60
units, if connecting to 208VAC power supply
move the red wire connected to the 240 ter-
minal of the transformer to the 208 terminal.
TABLE 6 - Control Transformer
Voltage Low Voltage Circuit Protection
(1) 208/230-1-60 Resettable breaker on transformer
(2) 208-3-60 Resettable breaker on transformer
(4) 460-3-60 Primary / Secondary fuses
(6) 220-1-50 Primary / Secondary fuses
(7) 380-3-50 Primary / Secondary fuses
OUTDOOR DISCONNECT SWITCH IS A
SAFETY DEVICE ONLY.
Turn off breaker to
indoor unit before servicing to avoid costly
damage to electronic control board.
IMPORTANT NOTE FOR 3-PHASE UNITS: If
on startup compressor is noisy and not
pumping, reverse L1 and L2 supply wires.
TABLE 5 - Indoor Loop Circulator Connections
Signal Description
115V
230V
Use a 2-conductor 14ga cable.
Connection for 115V circulator
Connection for 230V circulator
115/230 Connection for 115V or 230V circulator