Stulz C7000 - Zone for DFC Control

116 EN/06.2019/G57 © STULZ GmbH – all rights reserved
C7000 INSTRUCTIONS fOR a/C UNITS
An A/C unit is switched off as defective unit if a valid alarm occurs at this unit, in the same way as for the
sequencing.
When a Dualfluid unit changes over to DX operation due to a fault like a "water temperature too high"
alarm , this unit applies the nmax fan speed which is higher than the MAXFANSPEED of the CW standby
management.
The fan speed of the other units is not affected by this.
6.2.3 Zone for DFC control
The start temperature can also be entered as negative offset to the return air temperature.
Either in relation to the outside air temperature:
If T
outside
< T
return air
– Start temp.
air rel.
free cooling for DFC operation is enabled.
or in relation to the water inlet temperature 1:
If T
water
< T
return air
– Start temp.
water rel.
free cooling for DFC operation is enabled.
Some parameters as sequencing cycle and standby state are only operative in DX mode. DFC control is
described in detail in the manual "GE systems".
If a relative start value different from 0 K is set,
this value takes priority of the absolute start
temperature.
* water inlet temp. 2 in CW2-units.
Such a zone consists of GE type A/C units, drycoolers and external
glycol pumps. Concerning the hardware, the zone exists in the shape
of a common cooling water circuit and a common control of dry cool-
ers and external glycol pumps.
On the software level the zone operation is carried out by assigning
the A/C unit to the same zone and by setting the parameters "start
temperature, hysteresis" or "water start temperature (=water inlet
temperature 1*), hysteresis" different from "0". By this setting the
proportional GE control is activated. The zone parameters are trans-
mitted to all units/controllers of the zone and are assumed by these.
Config/Zone/more(Z2)