Trane CeilAir CW, Инструкция по установке, эксплуатации и обслуживанию, Страница: 10 / 52

Figure 4. Free cooling
Overview
10 AH-SVX008C-EN
The compressor activates, if the DX cooling stage enable-
temperature setpoint has been reached or if the control
valve position reaches 100% open for 240 seconds (default
compressor-on time delay). The free-cooling circuit and
the compressor operate in parallel on dual-circuit units to
provide maximum cooling. The 3-way control valve
continually modulates the flow of coolant in response to
temperature with the compressor running.
The compressor cycles off based on the normal
compressor temperature cut-out settings once the
setpoint is maintained.
As the outside air temperature increases above the
ambient air switch-over setting, the fluid cooler controls
cycle back to typical DX heat rejection allowing the leaving
fluid control setpoint to increase above the prevailing
ambient conditions. The indoor units inlet fluid
temperature sensor monitors the fluid temperature and
deactivates the free-cooling mode once the fluid
temperature increases above the user adjustable enable
setpoint. The compressor system becomes the primary
cooling source and will activate if the return air
temperature increases above the setpoint.
AWS Operation
The AWS (Alternate Water Source) configuration
illustrated in Figure 5 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 (see
“Free-cooling Operation,”
p. 9 ), when return air temperature rises to the AWS cut-in
temperature setpoint and if the chilled water inlet
temperature is 55
o
F or less (adjustable), AWS cooling
activates (the AWS control valve opens) and remains on
while the activation conditions exist.