Unit installation

Operating
58 SCXF-SVX01K-EN
Waterside Economizer Flow Control
Units equipped with a waterside economizer can be set
from the human interface panel for variable or constant
water flow.
Constant Water Flow
Two-way modulating control shutoff valves are wired,
controlled, and installed in unit. One valve is located in
economizer’s water inlet, and the other in condenser
bypass water inlet. When waterside economizer enables,
two-way valves modulate to maintain discharge air
temperature setpoint. As economizer valve opens,
condenser bypass valve closes, and vice versa. Full water
flow is always maintained through condensers. Both
valves will close in event of a power failure.
Variable Water Flow
Two-way modulating control shutoff valves are wired,
controlled, and installed in the unit. One valve is located in
the economizer’s water inlet, and the other is in the
condenser water inlet. When the economizer valve is
active, the condenser bypass valve closes.The
economizer valve modulates, thus water flow through the
unit modulates. If the water is cool enough for
economizing, but mechanical cooling is also required, the
economizer valve fully opens to establish full water flow
through the condensers. Whenever the water is too warm
for economizing and there is a call for cooling, the
economizer valve fully closes and the bypass valve fully
opens, establishing full water flow through the
condensers. Full water flow is always maintained through
the condensers when mechanical cooling is required. Both
valves close whenever cooling is not required, and in the
event of a power failure.
Unit Airside Components
The unit’s air delivery system consists of dampers,
enthalpy switch option, airside economizer option, filters,
low ambient sensors, and factory mounted single or
double wall plenums.
Supply Air Fan
The unit has a single supply fan that runs at a constant
speed. However, the fan may have the VFD option that
modulates airflow based on supply air temperature
control. Pressing the stop key on the HI will turn the supply
fan off.The fan is on continuously when a CV unit is in
Figure 37. Basic water piping, constant water flow
Condenser 1
Condenser 2
Condenser 3
Condenser 4
Figure 38. Intermediate water piping, variable water flow (L) and Intermediate piping with waterside economizer,
variable or constant water flow (R)
Condenser 1
Condenser 2
Condenser 3
Condenser 4
V2
V2
Condenser 1
Condenser 2
Condenser 3
Condenser 4
V1
Economizer