System Mode; Fan Control Output; Short Cycle And Maximum Cycles Per Hour - Contemporary Controls BASstat BAST-121C-B2 User Manual

System Mode

•
The default control type is heating only (2-stage binary or modulating analog).
•
Control Type can be selected by setting [MSV1] within one minute after setting menu
item [OPts] or [AV37] to a data "1". Once set, a factory reset will not affect this
setting.
•
Occupied set points and Unoccupied setpoints can be set individually for the
operating (heating or cooling) mode.
•
There is an automatic time delay (default 5 minutes) prior to second stage operation
in cooling (set dLyC or AV23) or heating (set dLyH or AV25). This is to prevent
damage to DX cooling or gas heating equipment.

Fan Control Output

•
Fan Output for Heating - the fan output for Heat mode is enabled "1" in [BV15] by
default. To let the RTU circuity control the fan during Heat mode – thermostat fan
control can be disabled by setting a "0" for Heat mode if desired [BV15].
•
Lowest Fan Speed is the speed the fan will default to after a control action (Heating
or Cooling). If the lowest fan speed [MSV4] is set as "Stop (1)", the fan will be
automatically shut off after the control action (Heating or Cooling) and a 2-minute fan-
off time delay. During this delay time, the AUTO icon will flash, and the fan will shut off
after the 2-minute time delay expires. If lowest fan speed is set to "Low (2)" the fan
will run continuously after a control action.
•
Fan Mode can be toggled between AUTO or CONTINUOUS by using the FAN button
on the thermostat (user) or BACnet object [MSV0] Fan Mode (BACnet supervisor).
By default, this value is set to "Auto (1)", the AUTO icon is displayed and the fan will
be controlled automatically. To put the fan in CONTINUOUS mode set to "Low(2)"
this will cause the fan to run continuously (no AUTO icon is displayed). Fan icon
spinning when fan is active. Optionally, the FAN button can be locked to limit user
access to this feature or the BACnet supervisor can be programmed to default the
thermostat to certain state at the end of an occupancy cycle.

Short Cycle and Maximum Cycles per Hour

There are short cycle and maximum cycles per hour protection for both cooling and heating
modes [AV23 – 26] Cooling Short Cycle Delay, Cooling Maximum Cycles per Hour and
Heating Short Cycle Delay, Heating Maximum Cycles per Hour.
•
The short cycle time (in minutes) will determine the minimum on time and minimum
off time of each stage before changing its state. The default setting is 3 minutes.
•
Maximum cycles per hour will count the number of cycles within one hour. When the
cycle count reaches the maximum cycles in an hour, it won't allow additional cycles
until the next hour.
•
When a stage change is pending due to a Short Cycle Delay or a Maximum Cycle
count, the Clock icon (
UM-15095000-AA0
) will appear on the LCD.
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