Install Instructions

26
IOM - HZH/HZV Series
Electrical - Power & Low Voltage Wiring
CAUTION! Use only copper conductors for field installed
electrical wiring. Unit terminals are not designed to accept
other types of conductors.
WARNING! Disconnect electrical power source to prevent
injury or death from electrical shock.
CAUTION!
WARNING!
Power Connection - Line voltage connection is made
by connecting the incoming line voltage wires to the “L”
side of the contractor as shown in the unit wiring diagram.
Consult electrical data tables for correct fuse size.
Transformer - All 208/230 voltage units are factory wired
for 208 volt. If supply voltage is 230 volt, installer must
rewire transformer. See wire diagram for connections.
ELECTRICAL - LOW VOLTAGE WIRING
Thermostat Connections - The thermostat will be wired
to the CXM/DXM2 board located within the unit control
box. Refer to the unit wiring diagram for specific details.
Low Water Temperature Cutout Selection - The CXM/
DXM2 control allows the field selection of low water (or
water-antifreeze solution) temperature limit by clipping
jumper JW3, which changes the sensing temperature
associated with thermistor LT1. Note that the LT1
thermistor is located on the refrigeravnt line between
the coaxial heat exchanger and expansion device (TXV).
Therefore, LT1 is sensing refrigerant temperature, not
water temperature, which is a better indication of how
water flow rate/temperature is affecting the refrigeration
circuit.
The factory setting for LT1 is for systems using water
(30°F [-1.1°C] refrigerant temperature). In low water
temperature (extended range) applications with
antifreeze (most ground loops), jumper JW3 should be
clipped as shown in Figure 17 to change the setting to
10°F [-12.2°C] refrigerant temperature, a more suitable
temperature when using an antifreeze solution. All
Comfort-Aire/Century units operating with entering
water temperatures below 60°F [15.6°C] must include the
optional water/refrigerant circuit insulation package to
prevent internal condensation.
Electrical - Line Voltage - All field installed wiring,
including electrical ground, must comply with the National
Electrical Code as well as all applicable local codes. Refer
to the unit electrical data for fuse sizes. Consult wiring
diagram for field connections that must be made by
the installing (or electrical) contractor. All final electrical
connections must be made with a length of flexible conduit
to minimize vibration and sound transmission to the
building.
General Line Voltage Wiring - Be sure the available
power is the same voltage and phase shown on the unit
serial plate. Line and low voltage wiring must be done in
accordance with local codes or the National Electric Code,
whichever is applicable.