Fan Cycling Control—DDNT, DSO, DDO
Available on all sizes of standard sound and Quiet-Line drycoolers. A thermostatic control cycles the fan on a single-fan
drycooler in response to leaving fluid temperatures. Two or more thermostats are employed on drycoolers with two or more
fans to cycle fans or groups of fans in response to leaving fluid temperatures. The thermostat setpoints are listed on the
factory-supplied schematic. They typically range from 35 to 45°F (2 to 7°C) for GLYCOOL applications and 65 to 75°F (18 to
24°C) for glycol applications.
Main Fan Control—DDNL
Available on all sizes of standard-sound and Quiet-Line drycoolers without pump controls. All fans run when an external
contact closure completes internal 24VAC circuit.
No Controls - DDNC
Available on all sizes of standard-sound and Quiet-Line drycoolers without pump controls. All fans are activated at full
speed when power is applied to the drycooler.
Pump Controls
Available on all Fan Speed and Fan Cycling Control drycoolers. Controls for pump(s) up to 7.5hp are built into the same
integral electric panel as the drycooler fan controls. Pump fuses, overload heaters and flow switch (dual pump control
models) are included with the Liebert® pump packages or must be field-supplied for field-supplied pumps.
Dual pump option—Provides controls for primary and standby pump. The flow switch senses loss of flow and switches to the
standby pump for continuous system operation in the event of a pump failure. An internal switch allows manual selection of
the lead/lag pump.
2.2.2 Typical System Configurations
The standard glycol-cooled precision air conditioning system includes these major components:
• indoor air conditioning unit with heat exchangers (refrigerant/glycol)
• glycol regulating valve
• outdoor air-cooled drycooler
• glycol pump(s)
• expansion/compression tank
• pump controls
• interconnection piping
• unit interlock control wiring
The piping general-arrangement drawings, listed in Table 2.3 on the next page, show single unit to drycooler loop
arrangement, multiple indoor units and multiple outdoor drycoolers using a dual pump package and on a common piping
loop. The drawings are included in the Submittal Drawings Contents on page65.
Additional field-supplied components, such as valves, expansion tank, strainers and flow or pressure switches are also shown
in the piping general-arrangement drawings. These components are necessary and should be included when designing a
system with one indoor and one outdoor unit on a piping loop or a system using multiple indoor and outdoor units on a
common piping loop. Larger systems may also benefit from an air separator (not shown).
2 Nomenclature and Components
9
To Next Page
Loading...
