Carrier 30RQS080 - 13.4 Units with Hydronic Module and Variable-Speed Pump - Temperature Difference Control

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Repeat until the design pressure drop / ow rate 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:
- Set water ow control to ‘pressure differential’
- Set the value of the required differential pressure
By default, the unit is congured at the maximum speed
(frequency: 50 Hz).
NOTES:
If during controlling, the low or high frequency limits are reached
before reaching the specied ow, keep the pressure differential
value to its lower or higher limit to enter in the control
parameters.
If the user knows in advance the pressure differential value at
the unit outlet to be maintained, this value can be entered
directly as data to be declared. You should not, however, avoid
the sequence of cleaning the hydronic circuit.
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The temperature probes at the heat exchanger inlet and outlet
(items 8 and 9 in the typical hydronic circuit diagram) are
used as means of control.
The system reads the measured temperature values, calculates
the corresponding temperature difference, compares it with
the user-selected set point value and modulates the pump
speed as necessary:
• If a higher delta T value than the set point is measured,
the ow rate is increased.
• If a lower delta T value than the set point is measured,
the ow rate is decreased.
This ow rate variation is realised, observing the minimum
and maximum admissible unit flow rates as well as the
minimum and maximum pump supply frequency values.
The delta T value maintained can in certain cases be different
from the set point value:
• If the set point value is too high (achieved for a lower ow
rate than the minimum value or a lower frequency than the
minimum value), the system settles at the minimum ow
rate or minimum frequency and this results in a lower delta
T value than the set point.
• If the set point value is too low (achieved for a higher ow
rate that the maximum value or a higher frequency than the
maximum value), the system settles at the maximum ow
rate or maximum frequency and this results in a higher delta
T value than the set point.
See with Carrier Service to implement the procedures
described below.
13.4.1 - Procedure for cleaning the hydronic circuit
Refer to the procedure for cleaning the hydronic circuit from
chapter 13.3.1
13.4.2 - 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:
- Set water ow control to ‘temperature differential’
- Set the value of the required differential temperature.
By default, the unit is factory congured at the minimum speed
(frequency: 50 Hz).