Emerson Liebert iCOM, Manual

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Operation
Liebert
®
iCOM
®
for Liebert DSE
™
36
External Humidifier Control—Optional
A factory-supplied option may be provided to allow a start-stop command to be sent to the control of a
remote-mounted humidifier.
Steam Generating Canister Humidifier
The Steam Generating Humidifier has its own separate control board that manages the canister and
steam rate. Liebert iCOM sends an On-Off command to relay a call for humidification.
3.5.3 Dehumidification
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
(compressors) will follow this dehumidification request as soon as it is higher than the request for
cooling.
DA125 and DA150 Dehumidification Control
The DA125 and DA150 are designed to maximize sensible cooling not latent cooling loads. With all
four compressors running, no reheat will be available at this dehumidification load point (Stage 4).
The room load must be 94.1kW (74% of unit capacity) to prevent overcooling the room at 85°F (29°C)
return air temperature. If the room load is too low to maintain the setpoint, the compressors will cycle
On and Off. During Stage 3, with three of the four compressors running, 10kW of reheat will be
available to offset cooling. During Stage 1 and 2, with one and two compressors running respectively,
30kW of reheat is available to offset cooling. For rooms with multiple units, Emerson ® recommends
performing dehumidification via Teamwork Mode to prevent compressor cycling in case of lightly
loaded rooms or having standard Liebert DS units available to perform dehumidification.
Liebert DSE units in dehumidification mode might not hold the temperature setpoint unless there is
sufficient room load. This will allow for better dehumidification of the room. The Liebert DSE will
allow the return air temperature to run down to 68°F (20°C) regardless of the temperature setpoint
during dehumidification mode of operation.
DA080 and DA085 Dehumidification Control
The DA080 and DA085 will run at lower evaporator temperatures than a DA125 and DA150. This
will result in a higher percentage of latent cooling than with a DA125 at a given return air
temperature.
Dehumidification on DA080 and DA085 is possible with only one circuit running. In dehumidification
mode, with one circuit running, a single stage 15kW electric reheat (customer option) is available to
help offset cooling for lightly loaded rooms, but overcooling will be allowed down to 68°F (20°C). If the
unit is running in dehumidification mode with both circuits (compressors) running, the electric reheat
is not available to offset cooling. All Liebert DSE units allow the indoor blower to run at a reduced
speed during dehumidification mode to increase the amount of dehumidification being performed.