Operating Description - Trane MERCURY EDAB 1105A Technical Manual

Operating description

AIR COOLED DIRECT EXPANSION UNITS (DXA)
The air cooled DX units extract heat from the room and transfer it to
the outside using air cooled refrigerant heat exchangers (condensers).
The room unit and external condenser form an autonomous sealed
circuit once installed. The TRANE remote condensers used with
MERCURY units include a precise electronic system to regulate the fan
speed to ensure trouble-free operation throughout the year under a wide
range of external air temperatures. Special attention has been paid to
the acoustic design of the condensers to minimise noise levels. A wide
range of combinations is available to meet different site requirements.
WATER COOLED DIRECT EXPANSION UNITS (DXW)
In the DX water cooled units, the heat extracted from the room is
transferred to water via a stainless steel brazed plate exchanger within
the unit.
The cooling water may be fed from the mains supply, a cooling tower
or a well (open circuit), or recycled in a closed loop cooled by external
coolers.
In the latter case, an anti-freeze mixture of water and ethylene glycol
is normally used.
The water cooled units have the advantage that the refrigerant
circuits are charged and sealed in the factory. This makes installation
extremely simple, eliminating the need for any site-installed refrigerant
pipework.
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