Installation, Operation, and Maintenance Manual
CA Series Heat Pumps - 8733851021 (2025/04) US
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10.1.3 Transformer Settings for 208/230-V Units
All 208/230-V units are factory wired to 240V by default. 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 208V . Refer to the unit wiring diagram for details.
WARNING
Personal injury hazard!
Never route control wiring through the same conduit as power supply wiring.
10.2 Electrical Low Voltage Wiring
10.2.1 Remote Mounted Controller (RMC) Wiring
For units with Remote Mounted Controller (RMC), the thermostat wiring is
connected to a terminal strip located on in the low voltage electrical box. Refer to
the unit wiring diagram for connection details and Figure 4.
On primary/secondary units connect the thermostat to the “Primary” terminal
block of the lead unit and the “Secondary” terminal block to the “Primary” terminal
block of the next unit, daisy chaining the units together as required. Note that there
is no limit to the number of units that can be connected together in this manner as
each unit provides its own low voltage power supply.
Optional
relays
UPM
Thermostat terminal block
Figure 4
Low Voltage Electrical Box. Remote Mounted Controller (RMC) layout
10.2.2 Thermostat to HVAC Equipment Wiring
The thermostat may not function properly if the total resistance of any of the
thermostat to HVAC equipment wires exceeds 2.5 ohms. To ensure that wire length
does not cause excess resistance, refer to Table 7 and ensure that the wires from
the thermostat to the HVAC equipment are not too long.
Copper Wire Gauge Maximum Wire Length
22 AWG (0,33mm2) 150 ft. (46m)
20 AWG (0,50mm2) 240 ft. (73m)
18 AWG (0,75mm2) 385 ft. (117m)
Table 2 Length by Wire Gauge for Thermostat to HVAC Equipment Wiring
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