Unit Installation
NOTICE
Operation of the unit on improper line voltage or with
excessive phase imbalance will be hazardous to the unit,
constitutes abuse, and may void the warranty.
WARNING
Properly-sized fuses or HACR circuit breakers must be
installed for branch-circuit protection. See the unit nameplate
for maximum fuse or breaker size.
For field electrical connection requirements, refer to the unit’s
wiring diagrams starting on page #57.
The unit is provided with a concentric knock-out for attaching
common tra
de sizes of conduit. Route power supply wiring
through this opening. Always connect the ground lead to the
grounding lug provided in the control box and power leads to the
line side of compressor contactor as indicated on the wiring
diagrams starting on page #57.
WARNING
All high-voltage connections must be torqued as specified by
the component’s manufacturer.
To minimize the transmission of vibration from the unit cabinet to
the building, enclose the power wiring to the heat pump in a
flexible conduit.
5.10.3 Units with Dual Power Supplies
Large EC units require dual power supplies, one power supply
feeds the c
ompressors and a second power supply feeds the
unit’s blower motor and control circuit. The compressors’ power
supply must be connected to the line (L) side of the compressor
contactors. The blower motor and control-circuit power supply
must meet the voltage, amperage, and phase requirements of its
load. Refer to the unit’s name plate for requirements.
5.10.4 Transformer Settings for 208/230-V Units
As factory built, all 208/230-V units are set to operate at 230
volts unle
ss the wire for the 208-V option is ordered. For job sites
with a 208-V power supply, the primary leads on the unit
transformer will need to be changed from 240-V to 208- V.
Refer to the unit wiring diagrams starting on page #57.
5.11 Electrical—Low-Voltage Wiring
5.11.1 Thermostat
Position the thermostat on an interior wall away from supply
ducts and l
ocations subject to direct sunlight and drafts. Place
the thermostat base plate against the wall so that it is level and
the thermostat wires protrude through the middle of the base
plate. Mark the position of the base plate mounting holes and drill
holes with a 3/16-inch bit. Install supplied anchors and secure
base plate to the wall.
Thermostat wire must be 8-conductor wire. The minimum gauge
needed i
s dependent on the length of the run. Refer to 5.11.3
Thermostat to HVAC Equipment Wiring. Strip the wires back 1/4-
inch (longer strip lengths may cause shorts) and insert the
thermostat
wires into the appropriate connectors. Refer to Table
4. Tighten the screws to ensure secure connections. See
instructions for the thermostat for detailed installation and
operation
information.
Thermostat wiring from the thermostat is connected to the
7-pin, screw-type terminal block, which is located in the
electrica
l component box.
WARNING
Never route control wiring through the same conduit as power
supply wiring.
Table 4 Thermostat Connection Options
Connection Function
Y1 First-Stage Compressor Operation
Y2 Second-Stage Compressor Operation
G Fan
O Reversing Valve (energized in cooling)
NC
Transformer 24 VAC Common (extra
connection)
C1
Transformer 24 VAC Common (primary
connection)
R Transformer 24 VAC Hot
H Hot Gas Reheat
16 |
EC Series Heat Pumps — 8733841499 (2024/05)
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