Carrier Aqua Force 30XA, Инструкции по установке, эксплуатации и обслуживанию

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8 - fREE-COOlING OPTION
8.1 - Characteristics
30Xa with Option 118a 252 302 352 402 452 502 602 702 752 802 852 902 1002
Operating weight* kg 3840 3880 3920 4780 4850 5330 6260 6410 6710 7010 7560 7860 8440
Refrigerant charge kg
Circuit A 36 37 37 54 56 64 64 64 72 76 79 76 83
Circuit B 38 38 39 37 39 39 64 68 64 67 70 79 87
Refrigerant charge, option 254 kg
Circuit A 60 64 ** 87 87 104 104 102 ** ** 133 ** 143
Circuit B 64 64 ** 56 56 56 90 97 ** ** 97 ** 132
* Standard unit and option 119
** Option 118A (free cooling) is not compatible with these units.
8.2 - Operating limits
Cooling mode
Evaporator
Minimum Maximum
Entering water temperature at start-up °C - 45
Entering water temperature during operation °C 6.8 21
Leaving water temperature during operation °C 3.3 26
Condenser (air) Minimum Maximum
Outdoor ambient operating temperature °C -10 55*
With winter operation option (option 28) °C -20 55*
free-cooling mode
Evaporator
Minimum Maximum
Entering water temperature at start-up °C - 45
Leaving water temperature during operation °C 3,3 26*
Condenser (air) Minimum Maximum
Outdoor ambient operating temperature °C -10 20
With winter operation option (option 28) °C -20 20
* Maximum configurable set-point
8.3 - Operation
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
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.
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