351579-YTS-B-0608
Johnson Controls Unitary Products
13
be turned off by turning off the RAH Sensor Enable option.
Thus, the option setting is used to reflect the desired operation
and mainly to control sensor failure alarms.
Economizer Loading to Control SAT - (ON) -
This tells the
control if it is going to use Economizer Loading to control
excessive SAT [supplying warmer outside air to keep SAT from
going too low]. This parameter is only applicable outside the
normal Economizer operation. During the Economizer
operation, the loading function is always performed and is an
integral part of the control algorithm.
Duct Static Setpoint - (1.5”WG) -
This parameter is applicable
only to
VAV mode of operation. This is the pressure setpoint that
the control will maintain when operating the fan in a VAV unit.
This setpoint is adjustable between 0”WG and 5”WG with the
default set to 1.5”WG.
Duct Static High Limit Setpoint - (4.5”WG) -
This parameter is
applicable only to VAV mode
of operation. This tells the control at
what Static Pressure to shut down the unit due to a Fan control
failure. This setpoint is to insure that we don't continue to operate
the Fan with an Inlet Guide Vane or VFD problem that could
cause the ductwork to fail from duct pressure. When the Static
Pressure reaches this setpoint (4.5”WG default), the control will
drive the supply fan control output to zero. If the static pressure
does decrease below the “Duct Static High Limit Setpoint” within
3 seconds after decreasing the supply fan control output to zero,
the control will resume normal operation. If there is no change in
static pressure after 3 seconds, the control will generate a High
Duct Static alarm, shut down all the outputs including the Fan and
shut down the unit. The alarm is written to the Error History Buffer
and will trigger storing a snapshot of Points Screen data along
with a date and time stamp. In networked applications, the alarm
flag is readable by the network. This parameter can be adjusted
from 0”WG to 5”WG with the factory default set to 4.5”WG.
The customer must be aware of the duct pressure design limit,
and what the duct pressure sensor will be reading when the peak
pressure is reached [the pressure pickup tube may not have
been located at the place of highest pressure in the system].
The alarm must be reset (after the problem that caused the
alarm is corrected) by resetting the controller by turning power
to the unit off and back on, or by reset command issued by an
external connection.
Morning Warm Up -
Is inferred from the entries in
Occupied/Unoccupied
Occupied -
(from settings in Weekly Schedule and Holiday
Schedule Tables 11 and 12.) - See discussion in Sequence of
Operation.
Unoccupied -
(from settings in Weekly Schedule and Holiday
Schedule Tables 11 and 12.) - See discussion in Sequence of
Operation.
VAV High Temperature SAT Setpoint for Cooling - (60 °F) -
The control will maintain this SAT when operating in VAV mode
with a thermostat that is calling for first stage cooling. This
parameter may be adjusted from 40 °F to 70 °F with 60 °F set
as the default value.
VAV Low Temperature SAT Setpoint for Cooling - (55 °F) -
The control will maintain this SAT when operating in VAV mode
with a thermostat that is calling for second stage cooling. This
parameter may also be adjusted from 40 °F to 70 °F with 55 °F
set as the default value.
VAV SAT Reset Setpoint - (72
°F
) -
This parameter is used
only
in VAV mode with a Space Sensor.
The control will switch
from the VAV Lower Cooling SAT Setpoint to the VAV Upper
Cooling SAT Setpoint when this Space Temperature Setpoint
minus 0.5 °F is reached. The control will switch from High
setpoint back to Low setpoint when the space temperature gets
2 °F above this setpoint. This is SAT reset based on Space
Temperature. The reset occurs in both Occupied and
Unoccupied modes and may be adjusted from 40 °F to 85 °F.
The factory default is 72 °F.
VAV Occupied Heating - (OFF) -
This option applies in VAV
mode with a Space Sensor and does not affect VAV Occupied
heating if requested by a thermostat. When this option is
toggled on, a VAV unit is able to operate heating in the occupied
mode as long as it is operating with a Space Sensor. If the
Space Temperature drops to 2 °F below the VAV SAT Reset
Setpoint the control will read the RAT. If the RAT is below the
Morning Warm Up RAT Setpoint the unit will enter the Occupied
Heating mode. Operation is the same as Morning Warm Up.
This parameter is factory set to OFF.
Comfort Ventilation Mode - (OFF) -
Comfort Ventilation is a
SAT control mode that controls SAT during “satisfied” periods in
a fairly wide temperature band, using mostly Outside Air, and
also cooling and heating stages as necessary. It is available
only on the Constant Volume unit.
To enable Comfort Ventilation, the programmable parameter
“Comfort Ventilation Mode” must be set to ON (default setting is
OFF).
For a detailed explanation of Comfort Ventilation, refer to the
Sequence of Operation in this manual.
Comfort Ventilation High Supply Air Setpoint - (80 °F) -
This
is the High Limit Setpoint for the Comfort Ventilation mode. For
a stable operation of Comfort Ventilation function, the High
Supply Air Setpoint should be set 10.0 °F or more above the
Low Setpoint.
Comfort Ventilation Low Supply Air Setpoint - (70 °F) -
This
is the Low Limit Setpoint for the Comfort Ventilation mode. For
a stable operation of Comfort Ventilation function, the Low
Supply Air Setpoint should be set 10.0 °F or more below the
High Setpoint.
Dirty Filter Switch - (OFF) -
This tells the control that a Dirty
Filter Switch is connected to it. The control will wait for ten
minutes after the switch has closed before declaring a Dirty
Filter Alarm. The alarm is written to the Error History Buffer. In
networked applications, the error flag is readable by the
network. The alarm will automatically reset when the error
condition is corrected.
The default is OFF.
