Units With Hydraulic Module And Variable Speed Pump - Temperature Differential Control; Units With Hydraulic Module And Variable Speed Pump - Setting A Fixed Flow Rate For The System - Carrier AQUASNAP 30RBM Series Installation, Operation And Maintenance Instructions

9.4 - Units with hydraulic module and variable speed
pump – Temperature differential control
The system flow rate has not been set to a nominal value.
The flow rate will be adjusted, by varying the pump speed, to
maintain a heat exchanger temperature differential value
defined by the user.
This is checked by the temperature sensors at the water
exchanger inlet and outlet (items 8 and 9 on the main water
circuit diagram).
The system reads the measured temperature values, calculates
the corresponding Delta T, compares it with the setpoint value
set by the user and then modulates the pump speed.
• This results in an increase in the flow rate if the Delta T°
exceeds the setpoint.
• This results in a decrease in the flow rate if the Delta T°
is less than the setpoint.
This modulation is limited only by the maximum and minimum
flow rates for the unit and by the maximum and minimum
allowable pump speeds.
The resulting Delta T° may, in certain cases, differ from the
setpoint value:
• if the setpoint value is too high (obtained for a flow rate
lower than the minimum value or a frequency less than
the minimum value), the system will stop once it reaches
the minimum flow rate or minimum frequency, which will
result in a temperature delta below the setpoint,
• if the setpoint value is too low (obtained for a flow rate
higher than the maximum value or a frequency greater
than the maximum value), the system will stop once it
reaches the maximum flow rate or maximum frequency,
which will result in a Delta T° above 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 adjusting the Delta T° setpoint
Once the circuit is cleaned, stop the forced start of the pump
and proceed to the configuration of the unit for the required
control mode.
Modify the control parameters:
• Water flow rate control method (temperature differential)
• Set the value of the required differential temperature.
The unit's default factory configuration is the minimum speed
(frequency: 30 Hz).
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9.5 - Units with hydraulic module and variable speed
pump – Setting a fixed flow rate for the system
The flow will be set to a nominal value. This value shall remain
constant, and will not be dependent on variations in the
installation's load.
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 flow rate
Once the circuit has been cleaned, set the required water flow
rate by adjusting the pump frequency on the user interface.
Stop the forced operation of the pump and proceed to the
configuration of the unit for the required control mode. Modify
the control parameters:
• Water flow rate control method (fixed speed)
• Constant frequency value.
The unit's default factory configuration is the minimum speed
(frequency: 30 Hz).