Manual 2100-711C
Page
25 of 45
Balanced Climate
TM
Mode
Balanced Climate™ is a great comfort feature that can
easily be applied under any normal circumstances.
If the Bard air conditioning system is being set up
in a typical environment where 72°F is the lowest
cooling setpoint, remove the Y1/Y2 jumper and install
a 2-stage cooling thermostat. This will increase the
humidity removal up to 35% and provide a much more
comfortable environment. This mode will also increase
the supply temperature when in heating mode. When
Balanced Climate mode is activated, it is employed in
both heating and cooling modes.
NOTE:
Units with mechanical dehumidification
require an additional connection to be made
when enabling Balanced Climate. Refer to
dehumidification supplemental instructions for
this step.
If the application is likely to require air conditioning
operation below 60°F outdoor conditions, a low
ambient control (LAC) kit must be installed.
The LAC
kit is equipped with an outdoor temperature switch
that disables Balanced Climate mode when the outdoor
temperature drops below 50°F. This prevents potential
evaporator coil freeze up issues. The LAC kit also
comes with an evaporator freeze protection thermostat
that cuts out the compressor if the evaporator begins to
freeze up.
If the unit is being installed with any ventilation
package, a Bard LAC kit must be installed.
Failure to
utilize an LAC with any air conditioner can cause coil
freeze up.
Balanced Climate can readily be applied to duct-free
(supply and return air grille) applications. It may also
be applied to ducted applications with
limited static
of 0.20" ESP (total including both supply and return
statics)
. Consult Bard Application Engineering for
details prior to implementation.
CAUTION:
Balanced Climate is not a replacement for
a dehumidification (hot gas reheat) unit for extreme
applications, but rather an enhancement feature for
limited climates and applications.
Defrost Cycle
The defrost cycle is controlled by temperature and time
on the solid state heat pump control.
When the outdoor temperature is in the lower
40°F temperature range or colder, the outdoor coil
temperature is 32°F or below. This coil temperature is
sensed by the coil temperature sensor mounted near
the bottom of the outdoor coil. Once coil temperature
reaches 30°F or below, the coil temperature sensor
sends a signal to the control logic of the heat pump
control and the defrost timer will start accumulating
run time.
After 30, 60 or 90 minutes of heat pump operation at
30°F or below, the heat pump control will place the
system in the defrost mode.
During the defrost mode, the refrigerant cycle switches
back to the cooling cycle, the outdoor motor stops,
electric heaters are energized and hot gas passing
through the outdoor coil melts any accumulated frost.
When the temperature rises to approximately 57°F, the
coil temperature sensor will send a signal to the heat
pump control which will return the system to heating
operations automatically.
If some abnormal or temporary condition such as a high
wind causes the heat pump to have a prolonged defrost
cycle, the heat pump control will restore the system to
heating operation automatically after 8 minutes.
The heat pump defrost control board has an option
of 30-, 60- or 90-minute setting. By default, this
unit is shipped from the factory with the defrost time
on the 60-minute pin. If circumstances require a
change to another time, remove the jumper pin from
the 60-minute terminal and reconnect to the desired
terminal. Refer to Figure 22 on page 26.
There is a cycle speed up jumper on the control. This
can be used for testing purposes to reduce the time
between defrost cycle operation without waiting for
time to elapse.
Use a small screwdriver or other metallic object, or
another 1/4" QC, to short between the
SPEEDUP
terminals to accelerate the HPC timer and initiate
defrost.
Be careful not to touch any other terminals with the
instrument used to short the
SPEEDUP
terminals.
It may take up to 10 seconds with the
SPEEDUP
terminals shorted for the speedup to be completed and
the defrost cycle to start.
As soon as the defrost cycle kicks in, remove the
shorting instrument from the SPEEDUP terminals.
Otherwise the timing will remain accelerated and
run through the 1-minute minimum defrost length
sequence in a matter of seconds and will automatically
terminate the defrost sequence.
There is an initiate defrost jumper (sen jump) on the
control that can be used at any outdoor ambient during
the heating cycle to simulate a 0°F coil temperature.
This can be used to check defrost operation of the unit
without waiting for the outdoor ambient to fall into the
defrost region.
By placing a jumper across the
SEN JMP
terminals (a
1/4" QC terminal works best) the defrost sensor mounted
on the outdoor coil is shunted out and will activate
the timing circuit. This permits the defrost cycle to be
checked out in warmer weather conditions without the
outdoor temperature having to fall into the defrost region.