Carrier 30KAV-ZE Series - Page 70

Hydraulic circuit cleaning procedure
Before proceeding, it is advisable to remove any possible
contamination from the hydraulic circuit.
■ Start-up the system pump by using the forced start command.
■ Control the frequency to the maximum value to generate the
highest possible ow.
■ If there is a ‘‘Maximum ow exceeded’’ alarm, reduce the
frequency until an acceptable value is reached.
■ Read the value of the ow on the user interface.
■ Let the pump run for 2 hours continuously to ush the system's
hydraulic circuit (presence of contaminating solids).
■ Perform another reading of the ow and compare this value
with the initial value. A reducing value of the ow indicates that
the lters on the system need to be removed and cleaned. In
this case, close the shut-o󰀨 valves on the water inlet and outlet
and remove the lters after draining the hydraulic part of the
unit.
■ Purge the air from the circuit.
■ Repeat until all fouling is removed from the lter
Procedure for controlling the Delta T° setpoint
Once the circuit is cleaned, stop the forced start of the pump and
proceed to the conguration of the unit for the required control
mode.
Modify the control parameters:
■ Water ow rate control method (Delta T)
■ Required Delta T value.
■ If necessary, the control PID parameters can also be adjusted
(refer to the control manual).
12.1.5.3 - Variable- speed pump - Control on constant
leaving water pressure
The system ow rate has not been set to a nominal value.
It will be adjusted by the system, by varying the pump speed, to
maintain a constant pressure value at the unit outlet, dened by
the user.
This is checked by the pressure sensor at the hydraulic module
outlet.
The system measures the pressure, compares it with the setpoint
value set by the user and then modulates the pump speed module
accordingly:
■ This results in an increase in the ow rate if the measurement
is below the setpoint,
■ This results in a decrease in the ow rate if the measurement
exceeds the setpoint.
This modulation is limited only by the maximum and minimum ow
rates for the unit and by the maximum and minimum allowable
pump speeds.
The maintained LWP (Leaving Water Pressure) value may, in
certain cases, di󰀨er from the setpoint value:
■ If the setpoint value is too high (corresponding to a ow rate
higher than the maximum value or a frequency greater than
the maximum value), the system will be limited to the maximum
ow rate or maximum frequency, which will result in a leaving
water pressure below the setpoint,
■ If the setpoint value is too low (corresponding to a ow rate
lower than the minimum value or a frequency less than the
minimum value), the system will be limited to the minimum ow
rate or minimum frequency, which will result in a leaving water
pressure greater than the setpoint.
Contact the manufacturer's service department to implement the
procedures described below
Hydraulic circuit cleaning procedure
Refer to the water circuit cleaning procedure.
Procedure for controlling the leaving water pressure
setpoint
Once the circuit is cleaned, place the hydraulic circuit in the
conguration for which the unit selection was performed (generally
all valves open and all cooling coils active).
Read the value of the ow on the user interface and compare it
with the theoretical value of the range:
■ If the ow rate read is greater than the specied value, reduce
the leaving water pressure setpoint on the user interface to
reduce the ow rate value;
■ If the value of the ow is lower than the specied value, increase
the leaving water pressure setpoint on the user interface to
increase the value of the ow.
Repeat until the unit's nominal ow rate at the required operation
point is achieved.
Stop the forced operation of the pump and proceed to the
conguration of the unit for the required control mode.
Modify the control parameters:
■ Water ow rate control method (xed pressure)
■ Required LWP value
■ If necessary, the control PID parameters can also be adjusted
(refer to the control manual)
NOTE: If, during adjustment, the low or high frequency limits
are reached before reaching the specied ow rate, keep the
outlet pressure value at its lower or higher limit as the control
set point.
12 - OPTIONS
70