Vertiv Liebert DSE - Heating

DA050 Dehumidification Control
The DA050 is designed to maximize sensible cooling not latent cooling loads.
The room load must be at least 37.6kW (74% of unit capacity) to prevent over cooling the room at 85°F
(29°C) return air temperature while in dehumidification mode. If the room load is too low to maintain the
setpoint, the compressor will cycle On and Off. For rooms with multiple units, we recommend performing
dehumidification via Teamwork mode to prevent compressor cycling in case of lightly loaded rooms.
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 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. 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 15-kW electric reheat (customer option) is available to help offset cooling for lightly
loaded rooms, but over-cooling 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 DSE units allow the indoor blower to run at a reduced speed during dehumidification
mode to increase the amount of dehumidification being performed.
DA125 Dehumidification Control
The DA125 is 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 94.1kW (74% of unit capacity) to prevent over-cooling 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, 10 kW of reheat will be available to
offset cooling. During Stage 1 and 2, with one and two compressors running respectively, 30 kW of reheat
is available to offset cooling. For rooms with multiple units, We recommend performing dehumidification in
Teamwork mode to prevent compressor cycling in case of lightly loaded rooms or by having standard DSE
units available to perform dehumidification. 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 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.
DA150 and DA165 Dehumidification Control
The DA150 and DA165 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 94.1kW (74% of unit capacity) to prevent over-cooling 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, 10 kW of reheat will be available to
offset cooling. During Stage 1 and 2, with one and two compressors running respectively, 30 kW of reheat
is available to offset cooling. For rooms with multiple units, We recommend performing dehumidification
via Teamwork mode to prevent compressor cycling in case of lightly loaded rooms. 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 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.
3.5.2 Heating
The Liebert® DSE is qualified for heating-only operation at temperatures not exceeding 80°F (27°C).
3 Pre-installation PreparationandGuidelines 21