DAVIS WeatherLink Irrigation Add. - Manual (Page 10)

10
of 3 days (Friday – Monday) or a weekly watering period (7 days). Since
most ET occurs during the day on a daily basis, using these values will
provide the most consistent results with your irrigation system. Your
watering cycle should represent the period of time it takes for all your
programmed cycles on your irrigation controller to start, finish and then
begin again. If you have some circuits on a 2 day cycle, and others on a 3
day cycle, it is recommended that you enter the longest of all the cycles you
use. In this case, enter 3 days. Please note that altering this value restarts the
cycle.
Irrigation Amount
Enter the amount of water in inches that your Irrigation system puts out
during one cycle. The cycle should be defined as recommended in the
previous paragraph. Typically, placing several cans around your lawn, and
measuring the depth of water in the cans with a ruler will provide you with
the Irrigation Amount for that location. Average all the locations to get the
number to enter into this dialog box. Since the Vantage Pro™ Console or
Weather Envoy™ calculates reference ET over regularly mowed grass, it is
best to enter the lawn sprinkler value. Consult your Vantage Pro™ Console
or Weather Envoy™ Manual for more information on ET.
Maximum Effective Rain
This function puts a “cap” on the amount of rain that is counted toward the
balance between Rain and ET. The amount entered in this dialog box
represents the total amount of rain during a 24 hour period that is counted. A
value of zero in this dialog box disables this function, so that all rain is
counted toward the Rain minus ET balance.
Rain Rate Cutoff
This function can be used to inhibit the irrigation cycle in the case where the
ET deficit has not been made up by rainfall, but rainfall is occurring at a high
enough rate that the combination of rainfall and irrigation may cause runoff
and thus waste water. The default value is 0.30”/hour, which represent a
heavy rain rate. Rain rate is an instantaneous calculation. Consult your
Vantage Pro™ Console or Weather Envoy™ Manual for more information
on Rain Rate. Once this function goes into effect, it inhibits the system until
the rain rate reaches zero, which is when it has stopped raining for at least 15