Operation Of Dehumidification - Data Aire dap4 User Manual

Operation of Dehumidification

Humidity Anticipation: When this feature is enabled (set in the factory menu), the
Humidity set point is offset +1% for every 1.5° that the return air temperature is
from the set point to a maximum 10° offset.
Fan Speed Assist: When this function is enabled in the factory menu, the fan
speed will be reduced (by 5 to 20%) during the dehumidification mode (CW or DX
units). The lower fan speed helps to condense the humidity in the air. Note: This
feature requires a discharge air temperature sensor to be installed.
Safeties Dehumidification will not run under the following conditions: Air Flow
Alarm, Floor Water alarm, Condensation Alarm or a Dehumidification Inhibit
command (from BMS).
Timed Safeties: Dehumidification mode cannot run within 5 minutes of a
humidification cycle.
Temperature Safeties: When Dehumidification mode is set to "In Limit" it will stop
if the temperature drops 2°F below the set point minus the dead band. Operation
will resume when the temperature rises back to the set point.
Dehumidification - Chilled Water
The method of CW valve modulation depends which type of humidity control
(selected in the factory menu) is selected:
Relative Humidity Control: When the humidity rises above the humidity Setpoint
+ Deadband the valve will open 100%. It will return to cooling modulation when
humidity drops to the humidity Setpoint.
Dewpoint Humidity Control: The CW valve will open 10% for every 0.1° that the
dewpoint rises above the High Dewpoint setpoint + deadband. When there is no
dewpoint demand, the CW valve will open 10% for every 0.1% that the relative
humidity rises above the humidity setpoint + deadband. The CW valve will
modulate to whichever has greater demand: Dewpoint control or Temperature
control.
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