Optimum Start; Standby Mode - KMC Controls FlexStat Application Manual

Optimum Start

NOTE: Optimum Start was added in firmware ver. R2.0.0.9.
Optimum Start uses historical performance data, outside temperature,
and length of the unoccupied period to calculate a pre-start time needed
to arrive near occupied space temperature setpoints at a scheduled time.
Optimum Start is enabled by setting OS Enable to ENABLE.
At midnight, Optimum Start reads and uses only the first scheduled ON
time for that day, and uses the following factors in calculating the opti-
mal start time:
• Three hours before scheduled occupancy, the pre-start time is calcu-
lated based on current space temperature and historical warm-up/
cool-down performance data.
• IF an outdoor air temperature sensor is installed (wired to AI4),
and IF today's OAT is 15° F (8.3° C) more conducive to warm-up/
cool-down than yesterday's (i.e., if in cooling mode and it's 15° F
cooler today than yesterday or if in heating mode and it's 15° F
warmer), the pre-start time is decreased by 10%. If today's OAT is
15° F (8.3° C) less conducive than yesterday's, the pre-start time is
increased by 10%.
• IF the schedule has been unoccupied for more than 24 hours, the pre-
start time is increased by 15%.
• The final calculated pre-start time is limited to between 15 minutes
minimum and 3 hours maximum.
Optimum Start is considered satisfied when the space temperature is
within 0.5 times the currently active setpoint span of the occupied set-
point. The length of time to reach Optimum Start being satisfied is then
used to calculate today's performance. This in turn is used to calculate
the historical performance rate for tomorrow's use. The last three days
performance are used to calculate the performance rate giving 3 times
weight to today's rate, 2 times weight to yesterdays and 1 times weight
to 2 days ago performance.
During Optimum Start mode, Occupied Mode is turned on and the unit
controls accordingly with the exception of Economizer Minimum Posi-
tion. If the unit is configured for economizer, during Optimum Start,
BAC-1xx63/1xxx63 Series (6 Relays and 3 Analog Outputs) Section
Econ Minimum Position is held to zero as ventilation is not needed until
scheduled occupancy begins.
Optimum Stop calculates the time before the scheduled off time that
the space temperature (without heating or cooling) may be allowed to
"drift" without exceeding the setpoint proportional band or span. (Nor-
mal ventilation will continue until the scheduled off time.)
NOTE: For maximum efficiency, if Optimum Start is enabled, set times
in schedules for when the room temperature should reach
the setpoint, not when heating/cooling equipment should
start (which would be earlier). Likewise, if Optimum Stop is
enabled, set Off times for when room temperature no longer
needs to be maintained at the occupied setpoint, not when
equipment should stop.

Standby Mode

NOTE: Standby Mode was added in firmware ver. R2.0.0.9.
On units equipped with a motion/occupancy sensor, Standby Mode is
available. Standby capability is enabled by setting Standby to Enable.
Standby Mode can only be entered into during the Occupied mode. If
Standby is enabled, Standby Mode is active if no motion is sensed for
the duration of the Standby Timer (30 minutes default). Once Standby
Mode is active, the active heating setpoint is set to the occupied heating
setpoint minus the Standby Offset (default 3° F or 1.6° C) and the active
cooling setpoint is set to the occupied cooling setpoint plus the Standby
Offset.
Upon detecting motion two times in three minutes, Standby Mode stops.
Although occupancy mode returns immediately to normal Occupied
Mode, the active setpoints transition from standby setpoints to normal
occupied setpoints over time. The active setpoints move 1° F (0.55° C)
closer to the occupied setpoints every fifteen minutes beginning immedi-
ately when Standby Mode stops. This continues until the active setpoints
reach their normal occupied setpoint values.
During Standby Mode, economizer minimum position is held to zero.
If a building automation system is present, the unit can manually be put
into Standby Mode by overriding BV36 (Standby Mode) to ON at prior-
ity 8. To return the unit to normal function, relinquish BV36@P8.
33 Application Guide L