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ELECTRICAL – Circuit Sizing
and Wire Routing
In the U.S.A., wiring must conform with current local codes
and the current National Electric Code (NEC). In Canada,
wiring must conform with current local codes and the cur-
rent Canadian Electrical Code (CEC).
Refer to the furnace or air handler installation instructions
for additional wiring application diagrams and refer to unit
nameplate for minimum circuit ampacity and maximum
overcurrent protection size.
24VAC TRANSFORMER
Use the transformer provided with the furnace or air han-
dler for low-voltage control power (24VAC - 40 VA mini-
mum).
Thermostat Control and Low Voltage
Control Wiring
EL18XCV Thermostat Control Options
The EL18XCV variable capacity units provide two thermo-
stat control options to provide application and installation
flexibility.
S30 Communicating Thermostat Control
The E18XCV variable capacity unit may be installed as
a fully communicating system consisting of an S30 Com-
municating Thermostat, a communicating indoor unit and
the EL18XCV variable capacity outdoor unit wired with (4)
communication wires (R, I+, I- and C) connected to the
EL18XCV Outdoor Unitary Control.
The EL18XCV variable capacity unit when wired as a ful-
ly communicating system will take full advantage of the
advanced diagnostics and control, Wi-Fi accessibility and
system operation parameters. Refer to the EL18XCV field
wiring diagram for an S30 communicating thermostat.
Conventional 24VAC Non-Communicating Thermo-
stat Control
The EL18XCV variable capacity unit may be installed us-
ing a conventional 24VAC non-communicating two-stage
cooling or single-stage cooling thermostat.
NOTE – The conventional 24VAC non-communicating
thermostat must have a compressor minimum on time of
three minutes to prevent compressor short cycling. The
Lennox M30, ComfortSense 7500, ComfortSense 3000
and many other commercially available electronic thermo-
stats provide this feature.
The EL18XCV unit will provide full variable capacity oper-
ation when installed with a conventional 24VAC non-com-
municating two stage cooling or single-stage cooling
thermostat. The EL18XCV outdoor control has advanced
control algorithms using the EL18XCV suction pressure
sensor to provide true variable capacity operation.
When utilizing a two-stage conventional 24VAC non-com-
municating thermostat, four wires are required to control
the outdoor unit (R, C, Y1 and Y2). Refer to the EL18XCV
field wiring diagram for a conventional 24VAC non-com-
municating 2-stage thermostat.
When utilizing a single conventional 24VAC non-commu-
nicating thermostat, three wires are required to control
the outdoor unit (R, C, and Y1) and Y1 is jumpered to Y2
in the outdoor unit. Note that the published performance
data is based upon the use of a two-stage thermostat. Re-
fer to the EL18XCV field wiring diagram for a convention-
al 24VAC non-communicating single-stage thermostat.
EL18XCV Low Voltage Control Wiring Connections
The EL18XCV variable capacity units are provided with
(2) RAST 6-Pin connections in the installation instruction
bag for connecting the field low voltage control wiring to
the EL18XCV harnesses in the low voltage control make-
up box. One RAST 6-pin connector is labeled with termi-
nals TST, DF, R, I+, I- and C. The second RAST 6-pin con-
nector is labeled with terminals DS, O, Y1, Y2, L and W.
Electric Shock Hazard. Can cause injury or
death. Unit must be properly grounded in
accordance with national and local codes.
Line voltage is present at all components
when unit is not in operation on units with
single-pole contactors. Disconnect all remote
electric power supplies before opening
access panel. Unit may have multiple power
supplies.
Fire Hazard. Use of aluminum wire with this product may
result in a fire, causing property damage, severe injury
or death. Use copper wire only with this product.
Failure to use properly sized wiring and circuit breaker
may result in property damage. Size wiring and circuit
breaker(s) per Product Specifications bulletin (EHB) and
unit rating plate.
ELECTROSTATIC
DISCHARGE
(ESD)
Precautions and
Procedures
Page 12
WARNING
WARNING
WARNING
WARNING
Electrostatic discharge can affect
electronic components. Take care
during unit installation and service to
protect the unit's electronic controls.
Precautions will help to avoid control
exposure to electrostatic discharge
by putting the unit, the control and the
technician at the same electrostatic
potential. Touch hand and all tools
on an unpainted unit surface before
performing any service procedure to
neutralize electrostatic charge.
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