Minimum Heat-Transfer Fluid Flow Rate (Units Without Factory-Fitted Hydronic Module); Maximum Heat-Transfer Fluid Flow Rate (Units Without Factory-Fitted Hydronic Module); Variable Flow Evaporator (Units Without Factory-Fitted Hydronic Module); System Minimum Water Volume - Carrier 30RBM 160 Installation, Operation And Maintenance Instructions

7.2 - Minimum heat-transfer fluid flow rate (units
without factory-fitted hydronic module)
The minimum heat-transfer fluid flow rate is given in the
paragraph "Water exchanger min. water volume and flow
rate".
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.
For a minimum heat-transfer fluid flow rate
Legend
1 Water heat exchanger
2 Recirculation
If the system flow rate is less than the minimum flow rate, there
may be a high fouling risk.
7.3 - Maximum heat-transfer fluid flow rate (units
without factory-fitted hydronic module)
The minimum heat-transfer fluid flow rate is given in the
paragraph "Water exchanger min. water volume and flow rate".
If the system's flow exceeds the unit's maximum value, it can be
bypassed as shown in the diagram.
For a maximum heat-transfer fluid flow rate
Legend
1 Water heat exchanger
2 Recirculation
It is limited by the allowable pressure drop for the water
exchanger.
Furthermore, it must ensure a minimum ΔT in the water
exchanger of 2.8 K, which corresponds to a flow rate of 0.09
l/s per kW.
7.4 - Variable flow evaporator (units without factory-
fitted hydronic 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 should contain
a minimum of 6.5 litres of water per kW instead of 2.5 l/kW.
24

7.5 - System minimum water volume

Whichever the system, the water loop minimum volume is
given by the formula
Volume = Cap (kW) x N litres
Application
Normal air conditioning
Process type cooling
Connection to a buffer tank
Incorrect
Incorrect

7.6 - System maximum water volume

Units with a hydronic 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.
Maximum water loop volume (litres)
30RBM/30RBP
Static pressure (bar)
Pure water
10% EG
20% EG
30% EG
40% EG
EG: Ethylene Glycol
N
2.5
6.5
Correct
Correct
160-260 300-520
1 2 2,5 1 2
2400 1600 1200 3960 2640
1800 1200 900 2940 1960
1320 880 660 2100 1400
1080 720 540 1740 1160
900 600 450 1500 1000
2,5
1980
1470
1050
870
750