Xylem IM255 AQUAVAR Intelligent Pump Controller - Manual (Page 70)

The next menu prompts the user to set the number of pumps in the system. Enter the
number of pumps in the system, including the variable speed pump. The selection will be
entered in to parameter [25-06] Number of pumps. If 2 pumps are selected, this means
that there is 1 variable speed pump and 1 fixed speed pump in the system. The fixed
speed pump will be controlled by relay 1.
The next menu prompts the user to enable or disable Run Time Equalization [25-04].
When the parameter is disabled the pumps will always be turned on (stage) in the order
of pump 1 then pump 2 and turned off (destage) in the order of pump 2 then pump 1.
Enabling this parameter will stage and destage the fixed speed pumps to provide equal
run time for each fixed speed pump.
The next menu configures the [25-20] Staging Bandwidth. The Staging Bandwidth (SBW)
sets a range around the setpoint in which no staging or destaging of pumps will occur.
This range is set to avoid frequent staging and destaging of pumps and to accommodate
normal fluctuations present in the system. The Staging Bandwidth (SBW) is set as a
percentage of the setpoint. For example if a setpoint of 50 psi is selected, and the SBW is
set to 10% then no staging or destaging of pumps will occur in the range of 45-55 psi.
The next menu configures the staging delay times. These delay times define the length of
time that the system pressure must be outside the SBW before staging or destaging
pumps will occur. For example if the [25-23] SBW Staging Delay is set to 10 seconds and
the system pressure is outside the SBW for more than 10 seconds a fixed pump will be
staged. If the pressure transitions back inside the SBW before the delay time expires, the
timer will reset. Parameter [25-24] SBW Destaging Delay sets the delay time associated
with pumps being destaged.
Operation
68 Aquavar ® Intelligent Pump Controller INSTRUCTION MANUAL