Xylem AquaBoost CS and VS Pumping Packages - Manual (Page 38)

• From the main screen, press the Z1 left arrow key two times to go to the user-adjustable
parameters screen.
The Lead Pump Minimum Run Timer screen will appear.
Sequence of operation for the duplex pumping system
Starting the lead pump
The lead pump can be started from either of the two pressure switches (2PS or 3PS) that
are provided on the right-hand side of the controller. The same applies to the lag pump.
This provides redundancy in the event of a failure of either pressure switch. Fully automatic
alternation is included in the standard controller. Pumps alternate any time that both
pumps stop.
Staging pumps together
Pumps can stage together if the pressure switch indicates that the system pressure is
unable to meet the required demand. This is the default setting of 0, which means that the
duty/standby switch is disabled. The pump stage/de-stage function is disabled when the
duty/standby switch is enabled by switching the setting to 1. When the duty/standby
switch is enabled, only one pump can run at a time; the other pump remains in standby
state.
Maintaining system pressure
If two pumps are running together to maintain the required system pressure, and the
system pressure increases, the system de-stages (stops) the lag pump. After the lag pump
has been de-staged and system pressure is still maintained, the system then stops the lead
pump as well.
The time interval between the lead pump stop and the lag pump stop must be at least 30
seconds. This is a fixed timer and no adjustments can be made.
Start delay
The start delay timer for both lead and lag pumps is a user-adjustable parameter that
prevents short cycling of pumps or false starting of pumps. The start delay timer for the lag
pump starts after the lead pump starts so that it is impossible for both pumps to be started
at the same time.
Minimum run time
Each pump has a minimum run timer. Pumps continue to run during that minimum run
time unless a failure occurs, such as pump failure or overload. The pump minimum run
timer is a user-adjustable parameter. Pump failure can be detected by a differential
pressure switch or by an overload failure. The pump fail proof timer is a user-adjustable
parameter.
Pump failure
When one pump is running and the system detects a failure on that pump, the system
stops the failed pump. The system then automatically switches to the other pump and
replaces the failed pump in order to meet the system demand. When pump failure occurs,
the pump failure indicator light illuminates.
Before you fix the failed pump, put the HOA switch in the OFF position. After the failed
pump is fixed, put the HOA switch in the Auto position.
You must manually reset the pump. Press the RESET button to turn off the pump failure
indicator light and return that pump to operational state.
Low-suction or high-temperature shutdown
A low-suction/high-temperature shutdown proof timer provides instantaneous shutdown
and prevents immediate restarting of the pumps. The proof time is adjustable between 0
to 99 seconds; the default setting is 5 seconds.
Commissioning, Startup, Operation, and Shutdown
36 AquaBoost CS and VS Pumping Packages Installation, Operation, and Maintenance Manual