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the minimum outside air at 20%. If the outside air drops below 20%, the burner will cycle
off.
See Minimum Ventilation.
100% Outside Air
The 100% Outside Air function automatically opens the outside air dampers and closes
the return air dampers. This function is activated whenever a contact is closed between
the appropriate terminals on the unit’s terminal strip located in the unit’s main control
panel. See the Typical Wiring Schematic and Multiplexed Input sections of this manual
for more information.
The 100% Outside Air function overrides all other damper
control functions. See User Configured PID Control for use with non-recirculating
units.
Minimum Ventilation
To change the Minimum Ventilation requires the use of a
BACview
or PC. The Minimum
Ventilation function defines the minimum outside air percentage and automatically
prevents the dampers from modulating below this point. This function can be used in
heating or cooling mode. If the unit served by this control is a direct-fired heater that
recirculates air before the burner, and is operating in the heating mode, the unit will
automatically keep the minimum outside air at 20%. If the outside air drops below 20%,
the burner will cycle off. To specify the Minimum Ventilation scroll through the menu
tree, locate the Setpoints branch and select Min Vent, and enter the desired outside air
percentage. The allowable range is 0% - 100% outside air. By physical design direct-fired
heaters, that recirculate air after the burner, supply a minimum of 25% outside air.
Freezestat
The Freezestat function automatically cycles the unit off if the supply air temperature
drops below the Freezestat setpoint for 3 continuous minutes. On all units there is an
initial 8-minute delay prior activation. The Freezestat function prevents the unit from
starting. The default for this setpoint is 45°F. To change the Freezestat setpoint scroll
through the menu tree, locate the Setpoints branch, select Freezestat SP, and enter a new
temperature. The allowable temperature range is 35°F - 80°F.
Clogged Filter
An optional clogged filter switch is required for this function. The Clogged Filter
function automatically notifies the user of a dirty filter condition. A Clogged Filter
indication will appear on the
BACview
. This function is activated whenever a contact is
closed between the appropriate terminals on the unit’s terminal strip located in the unit’s
main control panel. See the Typical Wiring Schematic and Multiplexed Input sections of
this manual for more information.
User Configured PID Control
This function is applicable to units without modulating return air dampers only.
The User
Configured
PID
Control function allows the user to control an analog output based on a
user defined analog input and setpoint. See the Typical Wiring and Unit Controller
Specification sections of this manual for more information regarding the inputs and
outputs. This function also allows the user to select the
PID
type (direct or reverse acting)
