Dehumidification Feature; Ventilation Features; Low Ambient Control (Lac); Outdoor Temperature Switch And Freeze Protection Thermostat - Bard W24HY-A Installation Instructions Manual

Wall mounted package heat pump
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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
dehumidification supplemental instructions for
this step.
To operate in Balanced Climate mode, a 2-stage cooling
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 40 – 41 for blower speed selection options.
Refer to page 28 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. During dehumidification, the
indoor blower speed is reduced to help with the humidity
removal. A humidity sensing thermostat or humidistat is
required to control dehumidification operation.
Ventilation Features (Optional)
See ventilation instructions provided with unit for low
voltage wiring.

Low Ambient Control (LAC)

The low ambient control is a pressure switch that is
attached to the liquid line of the system and monitors
high side pressure. Operation of the LAC occurs as
outdoor temperatures drop below 60°F. On/Off and
modulating controls are used which operate based
on pressure changes caused by outdoor temperature
changes. On/Off LAC operation cycles the condenser
fan on/off to maintain desired liquid pressure while
modulating LAC operation is factory adjusted and slows
the condenser fan speed (rpm).
Outdoor Temperature Switch and Freeze Protection
Thermostat
An outdoor temperature switch and an evaporator
freeze protection thermostat is supplied with all units
that have a low ambient control. The outdoor switch
disables Balanced Climate mode (if enabled) when
the temperature drops below 50°F. This prevents
potential evaporator coil freeze up issues. For units
with mechanical dehumidification, this switch must
remain disconnected when Balanced Climate mode
is not being used. Refer to unit wiring diagram. The
freeze thermostat cuts out compressor operation if the
evaporator begins to freeze up.
Alarm Relay Feature (Controls Option)
The alarm relay provides a set of NO (normally open)
and NC (normally closed) pilot duty contacts that
operate when the compressor control module locks out
compressor operation because of a high or low system
refrigerant pressure event.

Dirty Filter Switch Indicator (DFS)

The switch is adjustable and measures pressure drop
across the unit filter surface. When pressure drop is
higher than the switch setting, NO contacts are provided
to indicate the filter needs to be serviced. Refer to page
42 for instructions on making switch adjustments.

TABLE 3

Low Voltage Connections
Standard Units
Fan Only
Energize G
1st Stage
Cooling Mode/
Energize Y1, G
Balanced Climate
Energize Y2
to override
2nd Stage
Balanced Climate
Cooling Mode
mode when
Y1-Y2 jumper is
removed
1st Stage Heating
Energize Y1, B/W1
2nd Stage Heating
Energize Y1, B/W1,
(if employed)
W2
Ventilation
Energize A
Dehumidification
Energize D
(if employed)
Energize G, W2,
Emergency Heat
W3
Units w/
Economizers
Energize G
Energize Y1, G
(Free Cooling
or Compressor
Cooling)
Energize Y1, Y2, G
(Compressor
Cooling)
Energize Y1, B/W1
Energize Y1, B/W1,
W2
Energize A
Energize D
Energize G, W2,
W3
Manual
2100-790
Page
23 of 49

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