Dehumidification; Humidification (Bac-1X136 And Bac-1Xx136 Only) - KMC Controls FlexStat Application Manual

Night Flush
Night Flush mode uses the economizer only to pre-cool the building,
subject to the following conditions:
1. Night flush is intended to be seasonal, but may switch more than
once during swing seasons. Night Flush Enable is ENABLED when
OAT exceeds 70° F (21.1° C) and remains enabled until OAT drops
below 45° F (7.2° C). It then remains disabled until OAT once again
exceeds 70° F (21.1° C).
2. Night Flush Mode will be ON when all the following conditions are
true:
a. Night Flush Enable is ENABLED as above.
b. OAT is less than Econ Enble Temp – 1° F (0.55° C).
c. Space Temp is greater than Occ Heating Setpt + Min Setpt Diff.
d. The time is between midnight and the first scheduled Occupied
start time.
3. Night Flush Mode stops when any of the following conditions are
true:
a. Night Flush Enable is DISABLED as above.
b. OAT is greater than Econ Enble Temp + 1° F (0.55° C).
c. Space Temp is less than Occ Heating Setpt + Min Setpt Diff / 2.
d. The time is greater than the first scheduled Occupied start time.
During Night Flush mode, Econ Mode is ENABLED and the fan is called
for to run.
NOTE: To permanently disable the night flush option, write Inactive at
priority 8 to BV40.
Ventilation Pre-Purge
If OA Purge (0% default) is greater than zero, during the 60 minutes
prior to the first scheduled Occupied start time, the supply fan is called
for to run and the OA damper is set to OA Purge.
BAC-1xx63/1xxx63 Series (6 Relays and 3 Analog Outputs) Section

Dehumidification

On FlexStat models with a humidity sensor, dehumidification is offered
as an option. Once the dehumidification sequence is enabled through
the user interface, the dehumidification mode starts if the space humid-
ity rises above the dehum setpoint (adjustable, default 60%). The dehum
mode is stopped if the space humidity drops below the dehum setpoint
minus the dehum deadband (adjustable, default 5%). Dehumidification
mode being started also generates a call for fan if the fan mode is set to
"Auto."

Humidification (BAC-1x136 and BAC-1xx136 Only)

On BAC-1x136 and BAC-1xx136 models, humidification is offered as an
option. Once the humidification sequence is enabled through the U/I,
two other options are presented; humidifier valve type and an option to
lockout the humidifier sequence under certain conditions.
If "allow clg hum" is set to "no," then the humidifier valve is automati-
cally closed any time the FlexStat is operating in the cooling mode and
allowed to follow the normal humidifier sequence if the FlexStat is in the
heating mode.
If "allow clg hum" is set to "yes" (default selection), then the humidifier
valve follows the normal humidification sequence whether the unit is in
the heating or cooling mode.
If the humidifier valve is set to modulating, then the humidifier valve
will generally start to open as the space humidity drops below the
humidification setpoint and will modulate to fully open as the space
humidity falls below the humidification setpoint minus the humidity
deadband. Actual response may vary slightly due to PI action of the
control loop.
If the humidifier valve is set to two-position, then the humidifier valve
opens if the space humidity falls below the space humidity setpoint and
closes if the space humidity rises above the space humidity setpoint plus
the humidity deadband.
The humidifier valve closes any time the fan status is determined to be
"off."
39 Application Guide L