Wiring - Low Voltage; Low Voltage Connections; Ddc Connections; Unit Shutdown Feature - Bard W42HC-A Installation Instructions Manual

the upper control panel where the connections are
made. (The field wire shield can be removed for wire
installation.) If field power is supplied to the right of
side of the unit, the low voltage wires can be run under
the field wire shield to access the low voltage terminal
strip.
When field wires are supplied through the back of the
unit, flexible conduit must be extended through the
back of the unit and terminate into the knock-outs on
the upper control panel (see Figure 19).
Wiring – Low Voltage
All 230/208V 1 phase and 3 phase equipment have
dual primary voltage transformers. All equipment leaves
the factory wired on 240V tap. For 208V operation,
reconnect from 240V to 208V tap. The acceptable
operating voltage range for the 240 and 208V taps are:
Tap: 240 Range: 253 – 216
Tap: 208 Range: 220 – 187
NOTE: The voltage should be measured at the field
power connection point in the unit and while
the unit is operating at full load (maximum
amperage operating condition).
For low voltage wiring, an 18 gauge copper, color-coded
cable is recommended. See Table 7 on page 20 for
more information.

Low Voltage Connections

These units use a 24-volt AC low voltage circuit.
C terminal is the 24VAC common and is grounded.
G terminal is the indoor blower input.
Y1 terminal is the 1st Stage input for cooling.
Y2 terminal is the 2nd Stage compressor input for cooling
(if equipped with an economizer) or Y2 disables Balanced
Climate mode if the Y1-Y2 jumper is removed (see page
24).
B/W1 terminal is the reversing valve input. The
reversing valve must be energized for heating mode.
W2 terminal is the 1st stage electric heat (if equipped).
W3 terminal is the 2nd stage of electric heat or
emergency heat (if equipped).
A terminal is the ventilation input. This terminal
energizes any factory-installed ventilation option and
indoor blower.
D terminal is the dehumidification input. If installed, this
terminal energizes any factory-installed dehumidification
option.
L terminal is 24 volt alarm active output.
For units equipped with an alarm relay:
1 terminal is the normally closed contact on the relay.
2 terminal is the normally open contact on the relay.
3 terminal is the common contact on the relay.
Manual 2100-711F
Page 18 of 45

DDC Connections

11 terminal is filter switch, common contact on
auxiliary terminal strip (F Control option only)
12 terminal is filter switch, normally open contact on
auxiliary terminal strip (F Control option only)
Unit Shutdown Feature (Standard on All Models)
The RT terminal is the 24VAC transformer output,
and the R terminal is the 24VAC hot terminal for the
operation of the equipment. RT and R are connected
with a brass jumper bar which can be removed and RT
and R connected to an external NC (normally closed)
contact such as a fire/smoke detector that will cause
shutdown of the equipment upon activation.
Balanced Climate™ Feature (Standard on All Models)
All units are equipped with the capability of running
in Balanced Climate mode. This mode is designed to
enhance the comfort level by reducing the indoor airflow
amount and extending the run time to help extract
more humidity during cooling operation. In heating
mode, the reduced airflow provides a warmer supply
air temperature creating more comfortable heat. The
Y1 terminal is the 24VAC input for Balanced Climate
compressor cooling operation. The Y2 terminal is the
24VAC input for compressor cooling standard operation.
Y1 and Y2 are connected with a brass jumper bar which
can be removed to enable Balanced Climate mode.
Units with an economizer will not have the brass jumper
installed. Refer to vent manuals for instructions on how
Balanced Climate works with each vent.
NOTE: Units with mechanical dehumidification
require an additional connection to be made
when enabling Balanced Climate. Refer to the
dehumidification supplemental instructions for
this step.
To operate in Balanced Climate mode, a 2-stage heat
pump thermostat is required. The lower indoor airflow
operation is overridden by utilizing a 2-stage thermostat.
If the call for cooling is not satisfied within a given
time frame or temperature differential (specified by
the thermostat), the thermostat will send a signal to
Y2 which then increases the blower speed back to the
selected speed. See pages 36 – 37 for blower speed
selection options.
Refer to page 25 for additional Balanced Climate
requirements and limitations.
Dehumidification Feature (Optional)
The D terminal is the 24VAC input for dehumidification
operation on dehumidification hot gas reheat equipped
units. When 24VAC is applied to the D terminal, a
3-way valve solenoid is energized. The reheat coil
located behind the evaporator coil is then active to
reheat the supply air during cooling mode. This allows
humidity to be removed from the air entering the unit
without a large amount of sensible cooling capacity.