CIAT AQUACIAT POWER LD 602R-3500R, Instruction Manual, Page: 40 / 56

AQUACIAT
POWER
EN -
40
8 - STANDARD CONTROL OPERATIONS AND OPTIONS
8.2.1 Operating mode - control
The operating mode, i.e. cooling or heating, is determined
based on the following parameters:
ƒ
Unit on/off status [status]: Unit running status.
ƒ
Control type [ctrl_typ]: Local, Remote or Network.
ƒ
Local heat/cool selection [hc_sel]: Heat/Cool selection
when the unit is running in Local mode.
ƒ
Remote heat/cool selection [onsw_cr]: Heat/Cool
selection when the unit is running in Remote mode.
ƒ
Network heat/cool selection [HC_SEL]: Heat/Cool
selection when the unit is running in Network mode.
ƒ
Outdoor air temperature [OAT]: Heat/Cool setpoint
selection when the automatic changeover has been
enabled.
8.2.2 Heating / Cooling selection
Heating/Cooling selection applies to chillers with a boiler and
heat pumps. Heating/Cooling selection can be controlled
in various ways, depending on the active operating type. By
default, the cooling mode is selected.
Heating/Cooling selection can be determined:
ƒ
Locally at the unit using the HC_SEL item in the GENUNIT
menu.
ƒ
Remotely via the heating/cooling selection contact, if the
unit is in the Remote mode.
ƒ
Via a network command if the unit is in the Network mode.
Heating/Cooling mode can be set manually by the user or
automatically by the control. When heating/cooling is automatic,
the outdoor air temperature (OAT) determines the heat/cool/
standby changeover (see the SETPOINT menu for cooling
and heating mode changeover thresholds). The automatic
changeover is optional and requires user configuration
(GENUNIT – General Parameters).
On/Off
status
Control
type
Heating/
Cooling
selection
in local
mode
Heating/
Cooling
contact
in local
mode
Heat/Cool
select
Operating
mode
off - - - - cooling
on local cooling - - cooling
on local heating - - heating
on remote - on cooling - cooling
on remote - on heating - heating
on network - - cooling cooling
on network - - heating heating
8.3 Supplementary heating
AQUACIAT POWER LD chillers may be fitted with a boiler that
allows the unit to run in heating mode if required. The boiler is
active only when the unit is in Heating mode.
AQUACIAT POWER ILD heat pumps may be fitted with a boiler
or electric heaters which are used as heating replacement
when mechanical heating is not possible due to low outdoor
air temperature. Electric heating can be turned on to satisfy the
heating demand when mechanical heating is insufficient.
8.3.1 Boiler control
Boiler is activated when the outside air temperature is below
the user-configured boiler outdoor temperature threshold which
is by default set to -10°C (Boiler OAT Threshold in the BACKUP
menu).
8.3.2 Electric heating control
Electric heating stages can be activated as additional heating
when OAT is below the user-configured electric heating OAT
threshold which is by default set to 5°C (Elec Stage OAT
Threshold in the BACKUP menu).
Electric heating is allowed when:
ƒ
Unit is running at 100% capacity.
ƒ
Electric pull-down time elapsed.
ƒ
OAT is below the OAT threshold.
IMPORTANT: Please note that electric heating is not
allowed when the demand limit is active on the unit.
8.4 Water pumps control
The CONNECT TOUCH control can manage one or two water
exchanger pumps, determining the state of each pump as well
as its speed. The pump can be turned on when configured and
when the unit is running (Pumps Sequence in the PUMPCONF
menu).
The pump is turned off when the unit is shut down due to an
alarm, unless the fault is a frost protection error. The pump can
be started in particular operating conditions when the water
exchanger heater is active.
If the pump has failed and another pump is available, the unit is
stopped and started again with the second pump. If there is no
pump available, the unit shuts down.
Please remember that the configuration of pump(s) may differ
depending on the number and type of pumps that are available
for the specific unit (1 or 2 pumps / single-speed or variable-
speed pumps).
8.4.1 Variable speed pumps control
AQUACIAT POWER LD chillers as well as ILD heat pumps may be
fitted with one or two variable speed pumps.
Variable speed pumps give the possibility of saving the pumping
energy cost, providing precise water flow control and improving
the overall performance of the system. The frequency inverter
continuously regulates the flow rate to minimise the pump
power consumption at full load and part load.
Water flow management methods are as follows:
1) Fixed speed control (the control ensures a constant pump
speed based on compressor capacity).
2) Water flow control based on constant water delta pressure
(the control continuously acts on the pump speed to ensure
a constant delta pressure).
3) Water flow control based on constant delta T on the water
exchanger.
Fixed speed pumps can be either low or high pressure, whereas
variable speed pumps are always high pressure pumps.