Liebert 3000 manual Humidity HUM Control Method, Standard Custom Alarm Messages

Operation with Advanced Microprocessor Controls

Enable Alarms—Each individual alarm can be selected to be ENABLED (annunciated audibly, visu- ally, and communicated to a Site Products System) or DISABLED (ignored).

Enable Common Alarm—Each individual alarm can be selected to energize or to not energize the common alarm relay. If the energize common alarm function is set to YES, the relay is energized immediately as the alarm is annunciated and de-energized when the alarm condition goes away (only after the alarm has been recognized). If the function is set to NO, the alarm has no effect on the com- mon alarm relay regardless of whether the alarm is ENABLED or DISABLED.

Set Custom Alarms—The custom alarm messages can be from a list of standard alarm messages or you can write your own message.

NOTE

A maximum of two of the alarm messages can be your own message.

They can be in any location(s) 1 through 4. The text for custom alarms can be changed at any time by selecting “SET CUSTOM ALARMS.” To change the text for a custom alarm, select “SELECT ALARM.” Then, select the alarm you would like to change, 1 through 4. Using the UP/DOWN arrows will step through the list of five standard alarm messages (see list below) and the two custom alarms.

NOTE

The two custom alarm messages will be shown with what was previously programmed in them and can be changed.

Press ENTER to make your selection. To modify the two custom alarm messages, go back one screen and select “CHANGE CUSTOM TXT 1” (or 2). Text can be up to 20 characters in length and can be any of the following characters (or a blank space):

ABCDEFGHIJKLMNOPQRSTUVWXYZ#%*-0123456789.

Standard Custom Alarm Messages

•WATER UNDER FLOOR

•SMOKE DETECTED

•STANDBY GC PUMP ON

•LOSS OF WATER FLOW

•STANDBY UNIT ON

For more information concerning alarms, see 5.0 - Alarm Descriptions.

Humidity (HUM) Control Method

The user may select between relative (direct) and absolute (predictive) humidity control. If relative is selected, the RH control is taken directly from the RH sensor. If absolute is selected, the RH control is automatically adjusted as the return air temperature deviates from the desired temperature setpoint. This results in a predictive humidity control. The display will indicate % RH for both methods of con- trol, but the adjusted humidity reading will be displayed if absolute is selected. With absolute humid- ity control, the humidity control is automatically adjusted approximately 2% RH for each degree difference between the return air temperature and the temperature setpoint.

With relative humidity control, unnecessary dehumidification can result when overcooling occurs dur- ing a dehumidification cycle. This is because a higher than normal RH reading is caused by overcool- ing the room (about 2% RH for each degree of overcooling). This extends the dehumidification cycle.

Later, when the dehumidification ends and the temperature rises to the setpoint, the RH reading falls. The final RH reading will then be lower than actually desired. If the overcooling was significant enough, the RH could be low enough to activate the humidifier.

If absolute humidity control is selected, over-dehumidification is avoided. When overcooling occurs, causing an increase in the RH reading, the humidity control program “predicts” what the RH will be when the dehumidification cycle ends and temperature returns to the setpoint. This allows the dehu- midification cycle to end at the proper time. The predictive humidity control can reduce energy con- sumption by minimizing compressor and reheat operation, and eliminating unnecessary humidifier operation.

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