Data Aire dap4 touch, User Manual

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Operation of Chilled Water Cooling
The CW valve can be controlled by the Return or the Discharge air temperature.
Either an On / Off valve or a 0-10v analog valve may be used:
On / Off CW Valve (relay output DO-7 on minidap): The CW valve is opened
when the temperature rises above Se Dead Band and closed when the
temperature drops down to Setpoint. The valve can also be opened when in
dehum mode.
0-10v CW Valve (analog output Y2): a PID algorithm (set in factory settings
menu) is used to maintain the temperature setpoint. The PID algorithm modulates
the chilled water valve to constantly correct for error and maintain the temperature
setpoint. The tuning parameters for this algorithm are in the Factory Setting menu,
CW PID Modulation screen.
Note: If an Airside Economizer is installed, it is the first level of cooling when
outside air conditions are favorable. The cooling setpoint for CW modulation is
offset by +1 degree plus the Stage-To-Stage setting when the AE is in operation.
Energy Saver mode (Wtr Vlv configured as Engy Svg Cool or Aux Chill Wtr) the
Energy Saver does not become available unless the chilled water temperature is
below the energy saver set point minus dead band. During this time
“E/S Avail” is
displayed (piggybank icon on touch display). Should the chilled water temp rise
above the energy saver set point, a CW ES High Temp alarm will occur, the CW
valve will be closed for the
“Energy Saver Lockout Time” and DX cooling will take
over. Once the lockout timer expires, chilled water cooling can resume operation.
To maximize energy efficiency, DX assisted cooling does not begin until the CW
valve is fully open for the entire duration of the
“DX Assist Delay”. When DX is
assisting with cooling, the CW valve will remain fully open. After DX cooling is
finished and the
“DX -> ES Delay” has expired, the CW valve will return to normal
PID modulation. Please refer to the section
“Operation of DX Cooling” for
information regarding when the compressors will run in the energy saver mode.
E/S Changeover: This feature locks out CW energy saver and switches totally to
DX cooling if the air temperature reaches se de this setting. Once
locked out and the E/S Lockout timer has expired, temp must drop back to setpoint
for the Engy Saver function to resume. Range is from
“None” or 1 to 10 degrees
with default of 2 degrees. When set to
“None”, the energy saver will continue to run
along with any E/S assisting compressors regardless of the air temperature.