Pumps Control; Condenser Water Pump Control; Heating/Cooling Selection - Carrier 30XA Operation Instructions Manual

7.3 - Pumps control

The main control can manage one or two water exchanger
pumps, determining each pump on/off state. Both pumps
cannot run together. The pump is turned on when this option
is.configured.and.when.the.unit.is.running.
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.
Units.are.fitted.with.the.flow.switch,.allowing.for.the.water.
flow.control..For.more.information.about.actuators,.see.Water
flow switch in section 3.8.
7.3.1 - Pumps configuration
Basic pump configuration can be performed via the
Configuration.menu.(PUMPCONF.–.Pump.Configuration)..
Only logged-in users can access the menu (see also section
4.3.3). The unit must be stopped.
For units with two pumps, these pumps can be controlled
automatically or each pump can be started manually.
7.3.2 - Automatic pump selection
If two pumps are controlled and the reversing function has
been. selected. (PUMPCONF. –. Pump. Configuration),. the.
control.tries.to.limit.the.pump.run.time.to.the.configured.
pump changeover delay. If this delay has elapsed, the pump
reversing function is activated.
7.3.3 - Pumps protection
The control provides the option to automatically start the
pump each day at 14:00 for 2 seconds when the unit is off.
The heater for the heat exchanger and the water pump (for
units with a pump) can be energised so that it protects the
heat exchanger or the water pump against any damage when
the unit is shut down for a long time at low outdoor temperature.
If.the.unit.is.fitted.with.two.pumps,.the.first.pump.is.started.
on even days and the second pump is started on odd days.
Starting the pump periodically for a few seconds extends the
lifetime of the pump bearings and the tightness of the pump
seal. Periodical pump quick start can be selected via the
Configuration.menu.(Pump Sticking Protection, PUMPCONF
–.Pump.Configuration).

7.4 - Condenser water pump control

The water condenser pump control applies to air-cooled units
fitted.with.the.optional.heat.reclaim.module.as.well.as.water-
cooled units. This function ensures constant water pumps
control,.providing.the.optimum.condenser.water.flow.rate.
and operating cost savings.

7.5 - Heating/Cooling selection

For.units.configured.in.the.heat.pump.mode,.heating/cooling.
selection can be controlled in various ways, depending on the
active operating type. By default, the cooling mode is selected.
Heating/cooling control can be automatic or manual.
Heating/Cooling selection can be determined as follows:
• locally at the unit in the GENUNIT menu,
• remotely via the heating/cooling selection contact if
the unit is in the Remote operating type,
• via a network command if the unit is in the Network
operating type.
In the automatic mode, the outdoor air temperature
determines the heating/cooling/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).
Parameter status
On/off Control Heating/Cooling
status type selection in local
mode
off - -
on local cooling
on local heating
on remote -
on remote -
on network -
on network -
NOTE: Please remember that the automatic changeover
mode cannot be selected on water-cooled units.
Heating/Cooling Heat/Cool Operating
contact in local select mode
mode
- cooling
- cooling
- heating
on cooling cooling
on heating heating
- cooling cooling
- heating heating
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