Data Aire Mini dap4 Installation, Operation & Maintenance Manual page 49

DEHUMIDIFICATION FOR CHILLED WATER UNITS
1. All the standard dehumidification rules for dehumidification with compressors applies to chilled water units.
2. The chilled water valve responds to a change of the return air relative humidity (RH) after each adjustment period.
3. The dehumidification sequence for chilled water units is as follows:
Valve is OPENED to 100% at Humidity Setpoint + Humidity Deadband
Valve is CLOSED at Humidity Setpoint
AUTOMATIC FLUSH CYCLE for CHILLED WATER or HOT WATER COILS
If 100 hours elapses and the chilled water or hot water valve has not opened for normal cooling or heating, the valve
will automatically open for 30 seconds to flush the coil. The display module will not display a message indicating the
flush cycle is in progress.
HUMIDITY ANTICIPATION
1. Humidity anticipation is programmable: ON or OFF (See Menu J – Factory Settings)
2. When set to ON, the humidity setpoint is automatically modified to reduce excessive humidifying and
dehumidifying.
• The humidity setpoint is decreased by 1% for 1.5°F the return air temperature rises above the tem-
perature setpoint. The maximum amount the humidity setpoint may be decreased is 10% (15°F
above the return air temperature setpoint).
• The humidity setpoint is increased by 1% for every 1.5°F the return air temperature falls below the
temperature setpoint. The maximum amount the humidity setpoints may be increased is 10% (15°F
below the return air temperature setpoint).
TEMPERATURE and HUMIDITY SENSOR PROBLEM
1. A temperature sensor problem will activate all of the cooling stages if the unit is operating at the time of the
problem.
2. A humidity sensor problem will inhibit the humidification or dehumidification functions if the unit is operating at the
time of the problem.
COMPRESSOR SHORT-CYCLE ALARM
1. Compressor shot-cycle alarm is programmable (See Menu K – Alarms and Limits). A compressor short-cycle
alarm will activate if the compressor has been energized ten (10) times in a one (1) hour period.
2. The alarm is a warning only. Compressor operation will continue.
3. One cycle is a combination of compressor starts for cooling or dehumidification functions.
4. If the compressor is started ten (10) times in a one (1) hours period, the alarm will be activated and the message
"Comp Short- Cycle" will be displayed on the display module.
5. The compressor short-cycle time delay will be increased from five (5) to six (6) minutes for the next hour.
6. The short-cycle alarm will not clear until a one (1) hour period has passed with less than ten (10) compressor
starts.
49 • Mini dap4 User Manual