Product Overview

BAC-1xx63/1xxx63 Series (6 Relays and 3 Analog Outputs) Section 52 Application Guide S
Economizer Control
If the AHU application is congured for the economizer option, the
economizer sequence described in the Common Features section is fol-
lowed.
Dehumidification
If the dehumidication sequence is enabled on models BAC-
1xx163C/1x163C, the dehumidication mode is started and stopped as
described in the Common Features section. Upon activation of the dehu-
midication mode, the cooling valve is opened 100%. The heating valve
then reheats the space as called for in a modied heating sequence to
maintain the active cooling setpoint. Upon termination of the dehumidi-
cation mode, the valves return to their normal sequence.
An option is provided to prevent the FlexStat from going into dehu-
midication mode if it is presently operating in the heating mode. If
the option “allow htg dehum” is set to “yes,” then dehumidication as
described above can operate at any time. If the “allow htg dehum” op-
tion is set to “no,” then the dehumidication mode is allowed to operate
normally if the FlexStat is presently cooling. If the “allow htg dehum”
option is set to “no” and the FlexStat is presently heating, then the dehu-
midication mode is automatically stopped.
HPU (Heat Pump Unit)
Fan Control
The fan follows the base sequence for fan operation as listed above if the
heat pump application is congured for one stage of compressor.
If the heat pump application is congured for two stages of compres-
sor, the fan follows the base sequence for fan operation described in the
Common Features section with the following exception. If the fan mode
is set to “Auto,” the fan will start if the space temp rises above the active
cooling setpoint plus one half the cooling proportional band and will
stop if the space temp drops below the active cooling setpoint. If the
space temp drops below the active heating setpoint minus one half the
heating proportional band, the fan will start and stop when the fan rises
above the active heating setpoint. This will allow only one stage of heat-
ing or cooling to run if necessary.
Fan o delays apply as previously described.
Reversing Valve
The reversing valve can be congured through the user interface to be
energized on a call for heating (“B” function) or energized on a call for
cooling (“O” function). If the reversing valve is congured to be en-
ergized on a call for heating (“B”), the reversing valve output will be
energized any time there is a call for heating and de-energized on a call
for cooling.If the reversing valve is congured to be energized on a call
for cooling (“O”), the reversing valve output will be energized any time
there is a call for cooling and de-energized on a call for heating.
Compressor Staging
The sequence for the compressor staging depends on the number of
congured stages in the heat pump application:
• If the application is congured for one compressor stage, the
following sequence is used. If the space temperature rises above
the active cooling setpoint plus the cooling proportional band
AND the compressor has been o at least the minimum o time,
the compressor is energized. If the space temp drops below the
active cooling setpoint, the compressor is de-energized. If the
space temp drops below the active heating setpoint minus the
heating proportional band AND the compressor has been o the
minimum o time, the compressor will be energized. If the space
temp rises above the active heating setpoint, the compressor is
de-energized.
• If the application is congured for two compressor stages, the
following sequence is used. In the heating mode, if the space
temperature drops below the active heating setpoint minus
one half the heating proportional band AND the rst stage of
compressor has been o for at least the minimum o time, the
rst stage of compressor will be energized. If the space temp
further drops below the active heating setpoint minus the heat-
ing proportional band AND the rst stage of compressor has
been energized for at least the stage delay AND the second stage
of compressor has been o for at least the minimum o time,
the second stage of compressor will be energized. Upon rise in