Mechanical Dehumidification; Figure 26 Wall-Mount Unit Control Board - Bard MULTI-TEC W18AAPA Service Instructions Manual

For a more detailed operation description, see the 2100-
669 LC6000 Service Instructions manual.

Mechanical Dehumidification

Mechanical dehumidification is only available as a
factory-installed option that must be ordered with the
unit. It cannot be installed in the field on an existing unit.
Dehumidification will only become active if the unit
is connected to the LC6000 and the appropriate
conditions are present.
When the wall-mount unit receives a dehumidification
call from the LC6000, the wall-mount unit will
disable the economizer to force the system to use air
conditioning and prevent any additional humidity from
being introduced from outdoor air. The wall-mount
unit will then turn on the air conditioning system
which will remove moisture and cool the space. At the
same time, the 3-way dehumidification valve will be
opened to extend the run time of the cooling cycle and
prevent cool air from being introduced to the space.
The dehumidification sequence will run until the space
temperature reaches the heating setpoint or cooling
setpoint or the humidity setpoint is reached.
Smoke
Dirty Filter Switch
Comp. Alarm Relay
Low Pressure Switch
Damper Blade Switch
Damper Blade Switch
Digital Ground
Mixed Air Temp Sensor
Outdoor Air Temp Sensor
Return Air Temp Sensor
Outdoor Humidity Sensor
Evap. Temp Sensor
Analog Ground
24 VDC To Outdoor Air Sensor
Ground
2-10 VDC To Damper Actuator
Manual 2100-665G
Page 18 of 28
When the dehumidification command is first received
both cooling and reheat will be activated.
The cooling will shut off when the return air
temperature is 62°F to prevent the unit from causing
the system to go into heating mode (see Figure 25).
The compressor will turn on again once the return
temperature rises to 75°F.
The electric heat will operate to maximize cooling times
which will in turn remove moisture from the space. The
electric reheat will turn on when the temperature falls
to 73°F and will turn back off at 75°F.
The system will continue to operate this way until the
LC removes the call for active dehumidification.
The reheat coil is dependent on space load to warm the
temperature back up once the compressor is disabled.
A heating or cooling call will disable the dehumidification
call. Dehumidification can only take place when system
is not actively heating or cooling.
For a more detailed operation description, see the 2100-
669 LC6000 Service Instructions manual.
FIGURE 26
Wall-Mount Unit Control Board
24VAC GND
24VAC Hot
+ Communication Wire
- Communication Wire
24VAC +
Y TO Compressor CCM
Reheat Valve
24VAC +
Stage 1 Heat
Stage 1 Heat
2
Blower Relay
24VAC +
MIS-3869
MIS-3869