Carel MuChiller UCHBD00001130, Руководство пользователя

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ENG
5.14
Free cooling
The free cooling (FC) function can be enabled only on chiller units.
The type of free cooling is configured by parameter, and may be:
l
air free cooling, on air/water units equipped with air- water heat exchanger coils upstream of the
condenser coils and with modulating fan control;
l
remote air free cooling (see the specific paragraph);
l
water free cooling, on water/water units with mixing of the source water or via water- water heat
exchanger upstream of the evaporator and a 3-way modulating valve on the free cooling circuit.
User Code Description Def Min Max UOM
S U068
Free cooling: enable
0/1=no/yes
0 0 1 -
S U069 Free cooling: activation differential 3.0 0.0 99.9 K
S U070 Free cooling: hysteresis 1.5 0.0 99.9 K
S U071 Design free cooling delta T 8.0 0.0 99.9 K
S U072 Water free cooling: valve closing threshold 5.0 -999.9 999.9°C °C
S U073 Water free cooling: valve closing differential 3.0 0.0 99.9 K
M U074
Free cooling type
0=Air
1=Remote coil
2=Water
0 0 2 -
Free cooling is enabled when the outside source temperature is sufficiently lower than the temperature
of the water entering the unit, as shown in the following figure:
Fig.5.s
Key
FC Free cooling
DT Hysteresis
SP Activation differential
Temp User return temperature - outside source temp.
On air/water units, the fans are controlled based on the condensing temperature as long as the circuit’s
compressor is on; as soon as the compressor stops, the free cooling fan is controlled so as to maintain the
desired water temperature set point.
5.15
Types of free
cooling 5.15.1 Condensing unit with common air circuit
Free cooling is enabled based on the comparison between the user return water temperature and the
outside air temperature; this directly controls switching of the three-way valve, which allows the water
returning from the user terminals to flow through the free cooling coil before entering the evaporator.
Free cooling capacity is controlled by modulating the fan speed (with the compressors off); in combined
operation (free c mechanical cooling), fan speed is controlled so as to correctly manage the
condensing stage.
Inputs used:
To enable free cooling:
o
User return temperature;
o
Outside air temperature;
To manage capacity in free cooling mode:
o
(according to the control probe used) Return/delivery water temp.
66 | 5. Functions
µC0300053EN rel. 1.0 – 23.07.2018