Bard Q36A4D Supplemental Instructions

Supplemental Instructions
Q**A4D dehumidification models provide a unique
dehumidification circuit for periods of low outdoor
ambient temperature and high indoor humidity
conditions.
Refer to Spec Sheet S3620 for the standard features
of the base units and this manual for electrical data.
Dehumidification Circuit
The dehumidification circuit incorporates an
independent heat exchanger coil in the supply air
stream. This coil uses discharge gas to reheat the
supply air after it passes over the cooling coil without
requiring the electric resistance heater to be used for
reheat purposes. This results in very high mechanical
dehumidification capability from the air conditioner on
demand without using electric resistance reheat.
The dehumidification refrigerant reheat circuit is
controlled by a dehumidification valve directing
the refrigerant gas to the normal condenser during
periods when standard air conditioning is required.
During periods of time of low ambient temperature
(approximately 65° to 75° outdoor) and high indoor
humidity, a humidistat senses the need for mechanical
dehumidification. It then energizes both the compressor
circuit and dehumidification valve, thus directing
the hot refrigerant discharge gas into a separate
desuperheating condenser circuit, which reheats the
conditioned air before it is delivered to the room. The
refrigerant gas is then routed from the desuperheating
condenser to the system condenser for further heat
transfer. When the humidistat is satisfied, the system
automatically switches off. The result is separate
humidity control at minimum operating cost.
Models:
Q36A4D Q42A4D Q48A4D
Bard Manufacturing Company, Inc.
Bryan, Ohio 43506
www.bardhvac.com
Dehumidification Sequence of
Operation
Dehumidification is controlled through the thermostat
(if capable) or through a separate humidistat. On a call
for dehumidification mode of operation, the compressor
and dehumidification valve of the unit are energized
through circuit R - D to provide dehumidification.
Dehumidification will continue until the humidistat is
satisfied.
A cooling call takes precedence over a dehumidification
call as long as the cooling call is present. A heating call
takes precedence over a dehumidification call as long
as the heating call is present.
Refer to the chart on page 9 for a full list of outputs
that can be expected for different input combinations.
Balanced Climate TM
Enable Balanced Climate mode for cooling operation
ONLY and utilize a 2-stage thermostat to enhance the
comfort. To activate this mode, the jumpers between Y1
and Y2 on both low voltage terminal strips (blower section
and control panel) need to be removed. Refer to unit
wiring diagram for clarity.
This mode will allow the indoor blower to run at a
reduced airflow on the first stage of cooling. A 2-stage
thermostat connected to Y2 will then allow the airflow
to return to normal rated speed if the call for cooling is
not satisfied within the allotted time frame specified by
the thermostat.
Manual:
Supersedes: NEW
Date:
Mode
7960-923
8-13-21
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