Free-Cooling Option; Characteristics; Operating Limits; Operation - Carrier Aqua Force 30XA Installation, Operation And Maintenance Instructions

8 - fREE-COOlING OPTION

8.1 - Characteristics

30Xa with Option 118a
Operating weight*
Refrigerant charge
Circuit A
Circuit B
Refrigerant charge, option 254
Circuit A
Circuit B
* Standard unit and option 119
** Option 118A (free cooling) is not compatible with these units.

8.2 - Operating limits

Cooling mode
Evaporator
Entering water temperature at start-up
Entering water temperature during operation
Leaving water temperature during operation
Condenser (air)
Outdoor ambient operating temperature
With winter operation option (option 28)
free-cooling mode
Evaporator
Entering water temperature at start-up
Leaving water temperature during operation
Condenser (air)
Outdoor ambient operating temperature
With winter operation option (option 28)
* Maximum configurable set-point

8.3 - Operation

7
5
8
4
9
6
3
2
legend
1 Evaporator
2 Air condenser (coils)
3 Motorised two-way valve, discharge side
4 Compressor and oil separator
5 Principal electronic expansion valve (EXV)
6 Pressure and temperature measurement to calculate the sub-cooling upstream
of the pump
7 Motorised two-way bypass valve
8 Free-cooling expansion device (EXV)
9 Refrigerant pump
252 302 352
kg 3840 3880 3920
kg
36 37 37
38 38 39
kg
60 64 **
64 64 **
Minimum Maximum
°C - 45
°C 6.8 21
°C 3.3 26
Minimum Maximum
°C -10 55*
°C -20 55*
Minimum Maximum
°C - 45
°C 3,3 26*
Minimum Maximum
°C -10 20
°C -20 20
1
7
5
8
9
6
2
402 452 502 602
4780 4850 5330 6260
54 56 64 64
37 39 39 64
87 87 104 104
56 56 56 90
The change-over between the cooling and free-cooling
modes is automatically controlled (it is possible to block the
change-over to free-cooling by reconfiguring the machine -
see Controls IOM). The configurable parameters permitting
change-over are the outside air temperature and the leaving
water temperature set-point. As soon as the temperature
difference LWTstp - OAT is above 8 K the current capacity
in cooling mode is calculated and compared with the theo-
retical free-cooling capacity. This comparison authorizes/
stops the change-over to free-cooling.
After change-over to free-cooling all compressors are
stopped, the two (or four) two-way valves change to the free-
cooling position (the compressor functions are bypassed).
As soon as the valves open, the free-cooling pump is started.
This change-over logic takes around 4 minutes. Taking this
timing into consideration two cooling - free-cooling change-
overs are authorized per hour.
If the capacity supplied in the free-cooling mode is insuffi-
cient (set-point not reached), the unit automatically changes
over to cooling mode.
To optimize operation in free-cooling mode we strongly
recommend to use the set-point offset function. This favours
the change-over to free-cooling and increases the capacity
in free-cooling mode.
4
3
702 752 802 852
6410 6710 7010 7560
64 72 76 79
68 64 67 70
102 ** ** 133
97 ** ** 97
902 1002
7860 8440
76 83
79 87
** 143
** 132
31