![background image](http://html1.mh-extra.com/html/bac/nexus-nxf-0403n-cs2ts-h1/nexus-nxf-0403n-cs2ts-h1_operation-and-maintenance-manual_3315538015.webp)
13
13
Maintaining Water Quality
The iPilot
®
Control System is preset at the factory in accordance with BAC’s Water Quality
Guidelines. Water quality can be controlled as follows:
• A conductivity sensor is included to constantly measure water conductivity. During
operation, the drain valve will slowly open to control conductivity by draining water
from the spray water basin to meet the setpoint (the default setpoint is set at 3300
micro ohms/cm).
• BAC recommends adjusting the conductivity setpoint in the iPilot
®
Control System to
to best minimize water consumption and keep heat transfer surfaces scale-free. Refer
to “Corrosion Protection” on
page 30
for more details.
• A time-based bleed can be enabled by entering frequency and duration.
• An optional time-based drain can be enabled during periods of inactivity, and the
basin will not refill until building demand requires evaporative cooling. Refer to the
“iPilot
®
Control System Appendix” on
page 45
.
Fan Control
The fans are controlled by the iPilot
®
Control System by each of the following methods:
• The included temperature sensor at the outlet of the hCore® Heat Transfer Technology
is a negative temperature coefficient (NTC) sensor and sends a signal to the controller
in the iPilot
®
Control System, which modulates the fan speed accordingly.
• If the temperature signal is lost, an alarm will occur and the fans will continue to
operate at the most recent fan speed prior to loss of signal.
• If required, an analog signal (0-10V, 10-0V and 4-20mA) can be provided by the user
to control the fan. It is recommended to have the iPilot
®
Control System automatically
modulate the fan speed for optimal energy and water savings. This method of fan
control is only available in Energy Saver Mode, and Water Saver Mode with Winter
Guard enabled.
• For 2-fan modules (NXF-0603), ensure that both fans are operating simultaneously for
proper air and water management.
Cold Weather Operation
The iPilot
®
Control System has been designed to protect the equipment during freezing
conditions.
• All spray pumps will turn off below 35°F (1.7°C) ambient temperature, and the
equipment will automatically operate in Water Saver Mode with (Winter Guard
enabled).
Start-Up & Operation
Operation
Water Saver Mode
Spray Water Basin and Pump
Water Control
Maintaining Water Quality
Fan Control
Cold Weather Operation