Emergency Cooling; Unit Disable; Compressor; Enable - Bard MULTI-TEC W42ACE Series Service Instructions Manual

6. Press UP or DOWN keys to adjust parameter value.
7. Press ENTER key to save.
Economizer Note
The economizer and mechanical cooling can operate
simultaneously because the economizer uses the mixed
air temperature sensor.

Emergency Cooling

When return air temperature rises above 95°F, the unit
will enter emergency cooling mode and an alarm will be
displayed (unit can also be commanded by LC6000 to
enter emergency cooling mode). In emergency cooling
mode, if the unit is equipped with an economizer (and
the model does not indicate a blank off plate), the
economizer operation will ignore current setpoints.
If the return air temperature is above the outdoor air
temperature, the economizer will open and the unit
will enter optimized cooling. If at any point the return
air temperature falls below the outdoor air temperature
or the mixed air temperature falls below 65°F, the
economizer will close. This is done in an effort to cool
the space as quickly and efficiently as possible. This
feature will be disabled by a model number indicating
a blank off plate (model # position 10 set to 'B') which
disables all economizer function.

Unit Disable

The wall-mount unit can be disabled by opening a
dry set of contacts connected to Input DI1 on the
PLC board. This feature can be used in addition to
the emergency off feature provided by the LC6000
to ensure that the unit does not operate even when
in orphan mode. This feature is disabled by default
and must be enabled before the input will affect unit
operation. When the input detects open contacts, all
unit operation will stop and the dampers will close.
This is an automatic reset feature that will resume
operation as soon as the unit detects the contacts are
closed again.
For applications that require the dampers to close
rapidly, an additional relay should be installed that
either breaks the 24VAC power supply to each actuator
or breaks the low voltage power supply to all units.
In normal operation, the dampers can take up to 2
minutes to close from fully open. When the 24VAC
power is removed from the actuator, the dampers will
close in under 30 seconds using the spring return on
the actuator.
NOTE: Alarm logging and trend logging will not be
available if power is removed from the controller
and unit offline alarms will be recorded on the
LC6000.
To make adjustments to the unit disable option:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
USER password 2000.
Manual 2100-725C
Page 18 of 39
3. Press UP or DOWN keys to scroll to IO Config;
press ENTER key.
4. Press UP or DOWN keys to scroll to Digital In
Config C1; press ENTER key.
5. Press ENTER key to scroll to the variable in the
table that intersects Disable and Dir (see Figure
28).
6. Press UP or DOWN keys to change the direction
value from NO to NC or NC to NO.
7. Press ENTER key to scroll to the variable in the
table that intersects Disable and En.
8. Press UP or DOWN keys to change the enable value
from On to Off or Off to On; press ENTER key.
9. Press ESCAPE key several times to return to the
main menu.
FIGURE 28
Making Adjustments to Unit Disable

Compressor

Enable

The compressor will be enabled when stage 1 is enabled
and outdoor air conditions are not acceptable for
economizing. If the outdoor conditions are acceptable,
the compressor will run when stage 2 is enabled.

Delays and Run Time

The compressor will have a minimum run time of 180
seconds and a minimum off time of 120 seconds.
If the compressor is two stage, the second stage will
have a minimum delay of 120 seconds. The 2nd stage
will also have a minimum on time of 120 seconds.
When communicating with the LC, the delay between
compressors in units installed on the same shelter will
be managed by the settings configured in the LC.

Electric Reheat Dehumidification

Electric reheat dehumidification is only available as a
factory-installed option that must be ordered with the
unit. It cannot be installed in the field on an existing unit.
Dehumidification will only become active if the unit
is connected to the LC6000 and the appropriate
conditions are present.