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Sequential mode
Plant with variable flow on secondary circuit and independent pumps for every chiller, Set point chiller 5.0°C, COLD functioning.
Chiller 1 always On
Chiller 2 starts if SUW greater than 5.2°C
Chiller 3 starts if SUW greater than 5.2°C
Chiller 4 starts if SUW greater than 5.2°C
Chiller 5 starts if SUW greater than 5.2°C
Chiller 1 switches the compressors off on the basis of its own thermostat
Chiller 2 switched-off if SIW less than 7.8°C
Chiller 3 switched-off if SIW less than 8.8°C
Chiller 4 switched-off if SIW less than 9.3°C
Chiller 5 switched-off if SIW less than 9.6°C
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Load adjustment: TEMPERATURE
Probe position: the SUW probe (or probes) must be positioned on the
secondary circuit delivery, after the disconnecting device; the SIW
probe on the on the primary in the return input to the chillers after the
disconnecting device.
Plant features: management is optimised for plants where each chiller
controls its own pump (on/off together with the chiller) and with
secondaries with variable flow in the basis of the load.
SUW
SIW
PRIMARY
SECONDARY
Disconnect
This Adjustment directly controls the
delivery temperature to the secondary
circuit and it is possible to check up
to 3 branches of this circuit checking
up to 3 temperature probes SUW,
SUW2 and SUW3 (the latter only if the
pCOE expansion is used). The SUW,
SUW2,SUW3 delivery probes are consi-
dered for adjustment only if the relative
Flow meter contacts (respectively FL1,
FL2, FL3) are closed. In fact, the possi-
bility that every branch of the secondary
circuit is excluded due to stop of the
relative pump is also managed.
Conditions for switch-on of a new
chiller:
the switch-on of a new chiller is reque-
sted if one of the 3 delivery probes on
the secondary (SUW,SUW2 or SUW3)
reads a temperature greater than the
Leaving water temp. start chiller para-
meter (there is one for cold functioning
and one for hot functioning; the logic is
opposite for hot functioning)
SUW2 SUW3
Conditions for switch-off of a new
chiller:
the switch-on of the next chiller is
requested if the SIW probe reads a tem-
perature that is lower than the Return
water temp. stop chiller parameter. An
accurate calculation of the switch-off
temperature is requested, so that the
switch-off of a chiller sees to it that the
remaining chillers can guarantee a SUW
temperature that is less than the set
Leaving water temp. start chiller switch-
on set so as not to cause continuous
switch-on/switch-off of the chiller (there
is one for cold functioning and one for
hot functioning; the logic is opposite for
hot functioning)
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