Introduction
SS-SVX002B-EN
15
Alternate Water Source Operation
An alternate water source (AWS) system utilizes an
independent chilled water source to provide coolant to an
AWS cooling coil in the A/C unit. If AWS cooling is unable
to handle the load, the separate DX refrigeration circuit
can be utilized to assist. Similar to FC operation, when
return air temperature rises to the AWS cut-in temperature
set point, AWS cooling activates (the AWS control valve
opens) provided the chilled water inlet temperature is 55°F
or cooler (adjustable).
If the return air temperature rises to the compressor cut-in
set point or if the AWS control valve reaches 100% open for
the compressor delay period (20 seconds, adjustable), the
compressor turns on and operates in parallel with AWS
cooling. The compressor runs until the cut-out set point
temperature is reached provided the minimum run time
expires.
AWS cooling will continue if the return air temperature is
above the AWS cooling cut-in temperature set point and
the chilled water inlet temperature is 55°F or cooler.
If the chilled water temperature is above 55°F, AWS cooling
turns off (the control valve closes). If the compressor cut-
in set point is reached, the compressor turns on and
becomes the primary source of cooling.
In the event of loss of water flow during AWS operation,
the AWS control valve is closed and compressor operation
is activated.
Figure 9.
Alternate Water Source Diagram
HP
LP
Alternate Water
Source Cooling Coil
Alternate Water
Source Aqua-Stat
AWS
Cotrol Valve
DX - Cooling
Coil
Feeler
Bulb
Expansion
Valve
Refrigerant
Drier / Stainer
Refrigerant
Reclaim Port
Scroll
Compressor
Solenoid
Valve
Receiver
Flooded
Head Pressure
Control Valve
Remote Air Cooled
Condenser
Sight
Glass
Equaliz
er
Line
Flow
Switch
Pump
(by others)
Remote Liquid Chiller
(by others)
Relief
Valve
