Emerson iCOM user manual Dehumidification Low Limit, Dehumidification Compressor Quantity

Page 35

Operation

3.6.2Dehumidification

The Dehumidification Enable parameter (Service Menu, Options Setup) allows for enabling/disabling the dehumidification function.

A call for dehumidification is calculated in the same way as a cooling request. The components (valves, compressors) will follow this dehumidification request as soon as it is higher than the request for cooling.

Dehumidification Low Limit

Low Limit 1 and Low Limit 2 are used to avoid overcooling a room during dehumidification. When a low limit is reached, a compressor or the liquid cooling source that is used for dehumidification is dis- abled. It is re-enabled when the return air temperature rises. The Low Limit 1 and 2 settings are in the Service menu under Setpoints.

Low Limit 1: Low Limit 1 will disable one of two compressors for dehumidification. If only one com- pressor is set for dehumidification, or if the dehumidification source is chilled water, this limit will not be visible and will be inactive.

Low Limit 2: Low Limit 2 will disable both compressors for dehumidification. This limit will also stop dehumidification in single compressor units and in chilled water units.

The limits become active when the return air temperature drops below a temperature value equal to the sum of the temperature setpoint plus the value set on Low Limit 1 and 2 (the Low Limit settings are negative values).

A dehumidification source is deactivated if the return air temperature drops below the Deactivation Temperature, as in this example:

Temperature Setpoint:

70°F

Low Limit Value:

-7°F

Deactivation Temperature:

62°F

NOTE

If a cooling unit is equipped with SCR reheat and the SCR Control Type parameter is set to Tight mode, then Low Limit 2 will be ignored, see 3.5 - Temperature Control—Reheat.

Dehumidification Compressor Quantity

Under Factory Settings in the Advanced menu there is an item called Dehumidification With Comp. This item will be set to either 1, 2, 1 or 2, or BOTH. This setting determines which compressors are used for dehumidification. It also determines if Low Limit 1 will be available and impacts how the reheats will operate during dehumidification. The Dehumidification With Comp field is set when the cooling unit is built and should not be adjusted without consulting the factory first. Table 6 outlines which Low Limit settings will be available, based on the Dehumidification With Comp selection.

Table 6

Dehumidification With Comp settings

 

Available to Set Value

Dehumidification With Comp Setting

Default Setting On

 

 

 

 

 

 

[blank] (units without compressors)

All Chilled Water Units

 

 

 

 

 

 

1 (Compressor 1 dehumidifies only)

Liebert Challenger 3000™, Liebert DS™,

Low Limit 2 only

 

Liebert Deluxe System/3™

 

 

2 (Compressor 2 dehumidifies only)

—

 

 

 

 

 

 

1 or 2 (Compressor 1 and 2 alternate)

—

 

 

 

Low Limit 1 & 2

Both (both compressors dehumidify)

—

 

 

 

 

Low Limit 1 & 2 will be available only on cooling units with two compressors when Dehumidification With Comp is set to BOTH (see WARNING on page 30).

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Contents
Liebert iCOM Page Table of Contents Mounting a Large Display on a Wall Installing a Liebert Icom UNIT-TO-UNITNETWORKTeamwork Figures Tables Large and Small Displays FeaturesESC Icon Key Name Function Keyboard icons and functionsStatus menu, large display, graphical view Navigating Through the Liebert iCOM Menus Accessing SubmenusAccessing Submenus on Small Displays Accessing Submenus on Large DisplaysMenu tree-Small display, stand-alone or networked Entering a PasswordAdvanced Menu Unit Service Menu UnitStatus Menu System View Status Menu Unit 1 View User Menu Advanced Menu Unit # Service Menu Unit #Viewing Multiple Units with a Networked Large Display SET User menu icons Service menu icons Unit/Fan Control Start Stop Single Unit FunctionsAutorestart Loss of Power AlarmFan Alarm / Fan Protection Settings VSD Setpoint VSD Fan Speed SettingPump Down High Pressure AlarmCompressor Sequencing Digital Scroll High TemperatureCompressor Timing-Units With Two Compressors MBV Operation After Compressor is Turned Off Service Offset-Changing System Pressure SettingsMotorized Ball Valve in Digital Scroll Units Temperature proportional band Temperature Proportional BandTwo Single-Step Compressors Without Unloaders-Two-Step Compressor ControlCompressor Proportional Bands One Single-Step Compressor Without Unloaders-One-StepTwo compressors with unloaders four-step Two Compressors With Unloaders-Four-StepDigital scroll capacity modulation, 10-100% variable Digital Scroll CompressorsChilled Water Control Temperature Control-Second Cooling SourceDifferential Temperatures / Controls Comparator Circuit Delta T Temperature Difference Between Room and GlycolSecond cooling source and compressorized cooling Dual Cooling Source Temperature Control-ReheatReheat configuration types Glycool Cooling-Free-CoolingHeat On ½ Dead Band 100% Off ½ Proportional Band Decreasing TemperatureSCR Reheat Tight Mode Standard Mode Humidification Humidity ControlHumidification Dehumidification External Humidifier Control-Optional Humidification Infrared HumidifierParameters for infrared humidifier control Dehumidification Compressor Quantity Dehumidification With Comp settingsDehumidification Dehumidification Low LimitReheat During Dehumidification Temperature and Humidity Control TypesControl Types Humidity Sensor Reading Control Types Supply Limit-Optional High and Low, Temperature and Humidity EventsCustomer inputs User Inputs / Customer InputsEvent Types Time DelayEnable or Disable Event Types and PropertiesMain FAN Overload Event notifications-large or small display Possible Event NotificationsCalculating Unit Wellness Next Maintenance CalculationCalculation of Next Maintenance and Diagnostics Compressor 1 / 2 Settings and Diagnostics Parameters for Next Maintenance CalculationGeneral Maintenance Settings Fans / Heaters / Humidifier Settings and DiagnosticsNo Teamwork Teamwork ModeTeamwork Modes Application of Teamwork ModesTeamwork Mode 1 with two cooling units Standby and Cascade Standby Rotation Typical Standby Lead/Lag FunctionMinimum Network Switch Requirements Placement of Cooling UnitsU2U Hardware Cables and Network Switch Liebert iCOM U2U Ethernet Network Wiring for Unit-to-Unit Communications-U2USample Liebert iCOM network configurations Combining Large and Small Displays on a U2U Network Wiring a Liebert iCOM U2U Network Small DisplaysLarge Displays Wall-Mount Large DisplayWiring a small display for stand-alone operation Wiring a large display for stand-alone operation Liebert vNSA Ports available for connecting Liebert iCOM control devices298 84mm 305mm 14.25 362mm DPN001136 Rev Mounting Instructions Location ConsiderationsNecessary Mounting Items Liebert iCOM display dimensions Event log parameters Spare Part List-Large Display OnlySetpoints parameters Spare part list parameters-large display onlySensor data Set alarms parametersDisplay setup parameters Active AlarmsActive alarms parameters Total run hours parameters Timer parameters-Sleep ModeService contacts parameters Service Menu Parameters Unit diary parameters Unit Diary-Large Display OnlyMaintenance / wellness settings parameters Standby settings / lead-lag parametersWellness COMP2 Wellness HEAT2 Diagnostics / service mode parameters ALM REL 7of Delay Enable Disab Enable Disab Comp 1 Overload Unit X Disconnected WRN Loss of Power LOP MSG, WRN, ALM Call Service MSG, WRN, ALM High Temperature Sensor calibration / setup parameters System / network setup parameters-large display only GBP Network setup parametersStatic RAM Not Available, Invalid, OK HUM Steam Options setup parametersService contact info parameters Service Menu Parameters Service Menu Parameters Page That Ne tIti Ti n
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