Filter
Top Products
Irrigation Control Software Overview • 11-53
When a zone is bypassed to ON, the main water valve
will be turned ON immediately.
11.21.5.1 Bypass Failsafe
While each zone is bypassed to ON, a timer is checked.
If time has elapsed equal to or greater than the zone’s
cycle duration parameter, the bypass input will be ignored
and the zone will return to normal operation.
For a zone in Bypass Failsafe, its bypass input must be
set to OFF or NONE to reset the Bypass Failsafe and to
use the bypass input again.
11.21.6 Flow Sensor-Related Tests
11.21.6.1 Leak Test
For both Timed and Volume control types, if a flow
sensor is configured, water flow will be checked via a leak
test that is performed at the beginning of the cycle. During
the leak test the main water valve will be turned ON and
all zone valves will be set to OFF. After an amount of time
has elapsed equal to the Flow Alarm Delay, the Water
Flow input will be compared to the Minimum Flow for
Alarm setpoint. If the water flow is greater than the set
-
point, the flow alarm output will be set to ON and a Leak
alarm will be generated. If a Leak alarm occurs the cycle
will terminate. While a Leak alarm is active, no normal
cycles will run and the system status will be set to Leak
Detected.
A Leak alarm must be cleared by the user or the alarm
will return to normal after passing a leak test run by a
manual cycle. If an enabled zone is overridden to ON
during a leak test, it will cause the test to fail, resulting in a
false alarm.
11.21.6.2 Obstructed Zone Test
When a zone becomes active during a cycle, a timer is
reset. After time has elapsed equal to the flow alarm delay,
the water flow input will be compared to the Min Flow
alarm setpoint. If the water flow is less than the setpoint,
the flow alarm setpoint output will be set to ON, an
Obstructed alarm generated, and the zone will be removed
from the current cycle.
11.21.7 Service Modes
The Service Check cycle allows a service technician to
visually look for malfunctioning valves and leaks by
cycling each zone ON one at a time, starting with the first
zone. The active zone uses the Service On Time parame
-
ter and remains ON for the programmable time period
entered for Service On Time.
While in the Service Check cycle, any active irrigation
cycles will be terminated. The Service Check cycle will
continue looping until stopped by the user or the program
-
mable value in the Suspnd Failsafe field is reached.
11.21.8 Heat Cut In/Cut Out
Setpoints For Each Stage
If the current space temperature is greater than or equal
to the heat stage Cut Out setpoint, or the individual cool
-
ing stage is currently ON due to a call for cooling (Cut In
setpoint or dehumidification), and the current space tem
-
perature is greater than the individual COOL stage Cut In
setpoint, then begin turning the stage OFF by starting the
heat stage Off Delay countdown timer.
Or if the current space temperature is less than or equal
to the heat stage Cut In setpoint, begin turning the stage
ON by starting the heat stage On Delay countdown timer.
11.21.9 Cool Cut In/Cut Out
Setpoints For Each Stage
If the current space temperature is less than or equal to
the cool stage Cut Out setpoint, begin turning the cool
stage OFF by starting the cool stage Off Delay countdown
timer. If the current space temperature is greater than or
equal to the Cut In setpoint, begin turning the cool stage
ON by starting the cool stage On Delay countdown timer.
11.21.10 Dehumidification Control
Dehumidification control is implemented on an AHU
basis, not individual cooling or heating stages. Because of
implementation on an AHU basis, dehumidification con
-
trol is “woven” throughout the cool Cut In/Cut Out as well
as the heating Cut In/Cut Out control algorithms by calling
for increases or decreases in heating and cooling capaci
-
ties. The dehumidification algorithm does not directly
change the states of the heating or cooling, instead it
“influences” the staging process by calling for more, less,
or the same amount of cooling, and limit the amount of
heat used if a call for heating is necessary during dehumid
-
ification.
If the current space temperature is less than the dehu-
midification minimum space temperature, call for the end
of dehumidification.
If the current control value used for dehumidification
is greater than the dehumidification setpoint plus the dead
-
band divided by two (2), call for an increase in dehumidi-
fication capacity.
If the current control value used for dehumidification
is less than the dehumidification setpoint minus the dehu
-
midification deadband divided by two (2), call for a
decrease in dehumidification capacity.
11.21.11 Two Speed Fan Control
To determine proper fan speed, determine which heat-
ing and cooling stages are ON and if the user has set any
of the fan speeds for those stages to High. If any of the