Defrost Function; Additional Electric Heater Stage Control; Control Of A Boiler; Master/Slave Assembly - Carrier AQUASNAP 30RB Manual De Controles Y Soluciones De Defectos

5.11 - DEFROST FUNCTION

Defrost is activated, when the unit is in heating mode, in
order to reduce frost build-up on the air heat exchanger.
The defrost cycle can only be applied to one circuit at a
time. During the defrost cycle the fans of that circuit are
stopped, and the fourway refrigerant valve is reversed,
forcing the circuit to cooling mode. The fan can temporarily
be restarted during the defrost cycle. The defrost cycle is
fully automatic and does not require any setting.
5.12 - ADDITIONAL ELECTRIC HEATER STAGE
CONTROL
The heat pump units can control up to four additional
electric heating stages.
• The unit uses 100% of the available heating capacity, or
the unit is limited in its operation by a protection mode
(low suction temperature, hot gas or defrost sequence
in progress protection), and in all cases cannot satisfy
the heating load.
• The outdoor temperature is below a configured
threshold (see User 1 confi guration).
• The unit demand limit is not active.
The user may confi gure the last available electric heating
stages as a safety stage. In this case, the safety stage is
only activated in addition to the other stages if there is a
machine fault, preventing the use of the heating capacity.
The other electric heating stages will continue to operate
as described above.

5.13 - CONTROL OF A BOILER

NOTE: The control of the electric heating stages or of a
boiler is not authorised for slave units.
The unit can control the start-up of a boiler, if it is in heating
mode. When the boiler is operating, the unit water pump
is stopped.
A heat pump unit and a boiler cannot operate together.
In this case the boiler output is activated in the following
conditions:
• The unit is in heating mode, but a fault prevents the
use of the heat pump capacity.
• The unit is in heating mode, but works at a very low
outdoor temperature, making the heat pump capacity
insuffi cient. The outdoor air temperature threshold for
use of the boiler is fi xed at -10°C, but this value can be
adjusted in the User 1 menu.
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5.14 - MASTER/SLAVE ASSEMBLY

Two PRO-DIALOG Plus units can be linked to produce
a master/slave assembly. The two machines are
interconnected over the CCN bus. All parameters required
for the master/slave function must be confi gured through
the Service confi guration menu. Master/slave operation
requires the connection of a temperature probe at the
common manifold on each machine, if the heat exchanger
leaving water temperature is controlled.
The master/slave assembly can operate with constant or
variable fl ow. In the case of variable fl ow each machine
must control its own water pump and automatically shut
down the pump, if the cooling capacity is zero. For constant
fl ow operation the pumps for each unit are continuously
operating, if the system is operating. The master unit can
control a common pump that will be activated, when the
system is started. In this case the slave unit pump is not
used.
All control commands to the master/slave assembly (start/
stop, setpoint, heating/cooling operation, load shedding,
etc.) are handled by the unit which is confi gured as the
master, and must therefore only be applied to the master
unit. They will be transmitted automatically to the slave
unit. The master unit can be controlled locally, remotely or
by CCN com-mands. Therefore to start up the assembly,
simply validate the Master operating type (MASt) on the
master unit. If the Master has been confi gured for remote
control then use the remote voltfree contacts for unit start/
stop. The slave unit must stay in CCN operating type
continuously. To stop the master/slave assembly, select
Local Off (LOFF) on the master unit or use the remote volt-
free contacts if the unit has been confi gured for remote
control.
One of the functions of the master unit (depending on its
confi guration) may be the designation, whether the master
or slave is to be the lead machine or the follower. The roles
of lead machine and follower will be reversed when the
difference in running hours between the two units exceeds
a confi gurable value, ensuring that the running times of
the two units are automatically equalised. The changeover
between lead machine and follower may take place when
the assembly is started up, or even whilst running. The
running time balancing function is not active if it has not
been confi gured: in this case the lead machine is always
the master unit.
The lead machine will always be started fi rst. When the
lead machine is at its full available capacity, start-up delay
(confi gurable) is initialised on the follower. When this delay
has expired, and if the error on the control point is greater
than 1.7°C, the follower unit is authorised to start and the
pump is activated. The follower will automatically use the
master unit active setpoint. The lead machine will be held at
its full available capacity for as long as the active capacity
on the follower is not zero. When the follower unit receives
a command to stop, its evaporator water pump is turned
off with 20 seconds delay.