Carrier 30RBP-170R - Flow Rate Control without Hydraulic Module; Flow Rate Control with Fixed-Speed Pump

Water ow rate adjustment procedure
Once the circuit is cleaned, read the ow rate value on the user
interface and compare it to the theoretical selection value.
If the value of the ow rate read is greater than the specied value,
this indicates that the overall pressure drop in the system is too
low compared to the available static pressure generated by the
pump.
In this case, close the control valve (item 22) and read the new
ow rate value.
Proceed by repeatedly closing the control valve (item 22) until the
nominal ow rate is achieved at the unit's required operation point.
NOTE:
If the network has an excessive pressure drop in relation to
the available static pressure delivered by the unit pump, the
nominal water ow rate cannot be obtained (lower resulting
ow rate) and the di󰀨erence in temperature between the water
inlet and outlet of the water type heat exchanger will be
increased
To reduce the installation's hydraulic system pressure drop, it is
necessary to:
- Reduce the pressure drops of individual components (bends,
level changes, options, etc.) as much as possible;
- Use the correct pipe diameter;
- Do not extend the hydraulic systems
Example: unit with specied nominal ow rate of 10.6 l/s
Pressure drop, kPa
Water ow rate, l/s
Key
1 Unit pump curve
2 Pressure drop in the hydraulic module (to be measured on the pressure gauge
installed on the water inlet and outlet)
3 Pressure drop in the installation with wide open control valve
4 Pressure drop in the system after setting the valve to obtain the nominal ow
rate specied.
9.3 - Units with hydraulic module and variable-
speed pump – Pressure di󰀨erential control
The installation ow rate has not been set to a rated value.
It will be adjusted by the system, by varying the pump speed,
to maintain a constant operating pressure di󰀨erential value dened
by the user.
This is checked by the pressure sensor at the outlet of the water
type heat exchanger (item 10 on the typical hydraulic circuit
diagram).
The system calculates the measured pressure difference,
compares it with the setpoint value set by the user and then
modulates the pump speed module accordingly, resulting in:
- An increase in the ow rate if the measurement is below the
setpoint,
- A decrease in the ow rate if the measurement exceeds the
setpoint.
This variation in ow rate is limited by the maximum and minimum
permissible ow rate values for the unit and by the maximum and
minimum pump supply frequency values.
The maintained pressure di󰀨erence value may, in certain cases,
di󰀨er from the setpoint value:
- If the setpoint value is too high (obtained for a ow rate higher
than the maximum value or a frequency greater than the
maximum value), the system will stop once it reaches the
maximum ow rate or maximum frequency, which will result
in a pressure di󰀨erence below the setpoint,
- If the setpoint value is too low (obtained for a ow rate lower
than the minimum value or a frequency less than the minimum
value), the system will stop once it reaches the minimum ow
rate or minimum frequency, which will result in a pressure
di󰀨erence greater than the setpoint.
Contact the manufacturer's Service to implement the procedures
described below
Hydraulic circuit cleaning procedure
Before proceeding, it is advisable to remove any possible
contamination from the hydraulic circuit.
- Start up the unit pump using the override command.
- Set the frequency to the maximum value to generate a high
ow rate.
- If there is a “Maximum ow exceeded” alarm, reduce the
frequency until an acceptable value is reached.
- Read the ow rate 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 rate and compare this
value with the initial value. A decrease in the ow rate value
indicates that the filters in the system need to be
removed and cleaned. In this case, close the shut-o󰀨 valves
on the water inlet and outlet (item 19) and remove the lters
(items 20 and 1) after draining the hydraulic part of the unit
(items 6).
- Remove the air from the circuit (items 5 and 17).
- Repeat until all fouling is removed from the lter
9 - NOMINAL SYSTEM WATER FLOW RATE CONTROL
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