Minimum Energy Transfer Fluid Flow Rate (Units Without Factory-Fitted Hydraulic Module); Maximum Energy Transfer Fluid Flow Rate (Units Without Factory-Fitted Hydraulic Module); Variable Flow Water Type Heat Exchanger (Units Without Factory-Fitted Hydraulic Module); System Minimum Water Volume - Carrier 30RB-170R Installation, Operation And Maintenance Instructions

7 - APPLICATION DATA
NOTE:
Units equipped with variable speed drives (30RBP or 30RQP
or option 116V/116W)
If the air temperature is below -10 °C and the unit has been
de-energised for more than 4 hours, it is necessary to wait
two hours after the unit has been switched on again to allow
the variable drive to warm up.
7.2 - Minimum energy transfer fluid flow rate
(units without factory-fitted hydraulic module)
The minimum heat transfer fluid flow rate for different unit sizes
is given in the tables in paragraph "Water type heat exchanger
flow rate".
It is determined in order to allow sufficient exchange and prevent
the risk of excessive fouling.
If the system flow rate is less than the unit's minimum flow rate,
the exchanger flow can be recirculated, as shown in the diagram.
7.3 - Maximum energy transfer fluid flow rate
(units without factory-fitted hydraulic module)
The maximum heat transfer fluid flow rate for different unit sizes
is given in the tables in paragraph "Water type heat exchanger
flow rate".
This is limited by the permitted exchanger pressure drop. In
addition, there must be a minimum Delta T of 2.8 K, which
corresponds to a flow rate of 0.09 l/s per kW.
If the system flow rate exceeds the unit's maximum value, it can
be bypassed as shown in the diagram.
7.4 - Variable flow water type heat exchanger
(units without factory-fitted hydraulic module)
A variable water heat exchanger flow can be used in standard
units. The flow rate must be higher than the minimum flow given
in the table of permissible flow rates and must not vary by more
than 10% per minute.
If the flow rate changes more rapidly, the system's water volume
should be increased and reach a value of at least 6.5 litres of water
per kW.
30
Key
1 Water-cooled heat exchanger
2 Recirculation
Key
1 Water-cooled heat exchanger
2 Bypass
7.5 - Minimum system water volume
Whichever system, water volume for the water loop (to be provided
between the unit and any customer valves outside the machine)
is given by the formula
Volume = Cap (kW) x N litres
Application
Air conditioning – cooling
Air conditioning – heating
Industrial process type cooling
(1) Depending on the unit capacity - minimum water loop volume 1300 l
Where "Cap" represents the cooling or heating capacity (kW) under
the installation's nominal operating conditions. This volume is
necessary for stable operation. It may be necessary to add a buffer
water tank to the circuit in order to achieve the minimum volume.
The tank must itself be internally baffled in order to ensure proper
mixing of the liquid (water or brine). Refer to the examples below.
Connection to a buffer tank
Incorrect
Incorrect
7.6 - Maximum system water volume
Units with a hydraulic module may include an expansion vessel
which limits the volume in the water loop.
The table below gives the maximum loop volume compatible with
the expansion vessel (for pure water or ethylene glycol depending
on the system's various concentrations and static pressures).
If this volume is less than the volume of the installed loop, then it
is necessary to add an extra expansion vessel within the system.
30RB/RBP or 30RQ/RQP
Static pressure
Pure water 2400 1600 1200 3960 2640 1980
10% EG 1800 1200
20% EG 1320
30% EG 1080
40% EG 900
EG: Ethylene Glycol
3,0 - 8,0
Correct
Correct
165-270 310-950
1 2 2,5 1 2
900 2940 1960 1470
880 660 2100 1400 1050
720 540 1740 1160
600 450 1500 1000
N
2,5
(1)
6,5
2,5
870
750