CIAT PRO-DIALOG+, Instruction Manual

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5.3 - Heat exchanger water pump control
The unit can control one or two heat exchanger water pumps.
The pump is turned on when this option is configured (see
PUMPCONFIG) and when the unit is in one of the on modes
described above or in delay mode. Since the minimum value for
the delay at start-up is 1 minute (configurable between 1 and 15
minutes), the pump will run for at least one minute before the first
compressor starts.
The pump is kept running for 20 seconds after the unit goes to
stop mode. The pump keeps working when the unit switches from
heating to cooling mode or vice-versa. It is turned off if 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 heat exchanger heater is active (see chapter 5.5). See
chapter 5.14 for the particular heat exchanger pump control for
the follower unit (master/slave assembly).
If two pumps are controlled and the reversing function has been
selected (see PUMPCONF configuration), the control tries to limit
the pump run time delta to the configured pump change-over
delay. If this delay has elapsed, the pump reversing function is
activated, when the unit is running. During the reversing function
both pumps run together for two seconds. If the pumps are of the
variable flow rate type pump reversal will take place at the next
machine start-up.
If a pump has failed and a secondary pump is available, the unit
is stopped and started again with this pump.
The control provides a means to automatically start the pump
each day at 14.00 hours for 2 seconds when the unit is off. If the
unit is fitted with two pumps, the first pump is started on odd
days and the second pump is started on even days. Starting the
pump periodically for a few seconds increases the life-time of
the pump bearings and the tightness of the pump seal.
5.4 - Control interlock contact
This contact checks the status of a loop (water flow switch and
customer safety loop, see chapter 3.6). It prevents the unit from
starting if it is open when the delay at start-up has expired. This
open contact leads to an alarm shut-down, if the unit is running.
5.5 - Heat exchanger frost protection
The heater for the heat exchanger and the water pump (for units
with a pump) can be energised to protect the heat exchanger,
if it may be damaged by frost, when the unit is shut down for a
long time at low outdoor temperature.
NOTE: Heat exchanger heater control parameters can be
modified, using the Service configuration.
5.2.2 - Heating/cooling/auto selection
The table below summarises the unit heating/cooling opera-
tion, based on the following parameters:
• Control type: indicates whether the unit operates in local,
remote or Network mode. See section 5.1.
• Unit on/off status: indicates whether the unit is shut down
(not authorised to start) or in operation (or authorised to
start).
• Heating/cooling/auto selection in local mode: operating
mode selected via the user interface. See GENUNIT menu.
• Remote heating/cooling contacts: these contacts are only
active if the unit is under remote control.
• HC_SEL: this network command permits heating/cooling/
auto control, if the unit is in Network operating mode.
• Outside temperature: determines the operation, if the unit
is in automatic heating/cooling/standby changeover mode.
PARAMETER STATUS
ON/OFF
STATUS CONTROL
TYPE HEATING/COOLING
SELECTION IN LOCAL MODE REMOTE HEATING/
COOLING CONTACTS HC_
SEL OUTDOOR TEMPERATURE OPERATING
MODE
Off - - - - - Cooling
On Local Cooling - - - Cooling
On Local Heating - - - Heating
On Local Auto - - > Cooling threshold Cooling
On Local Auto - - < Heating threshold Heating*
On Local Auto - - Between cooling and heating thresholds Standby
On Remote - Cooling mode - - Cooling
On Remote - Heating mode - - Heating
On Remote - Auto mode - > Cooling threshold Cooling
On Remote - Auto mode - < Heating threshold Heating*
On Remote - Auto mode - Between cooling and heating thresholds Standby
On Network - - Cooling - Cooling
On Network - - Heating - Heating
On Network - - Auto > Cooling threshold Cooling
On Network - - Auto < Heating threshold Heating*
On Network - - Auto Between cooling and heating thresholds Standby
* Does not apply to cooling only units that do not control a boiler.
5 - PRO- CONTROL OPERATION
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