ISY-99i/ISY-26 INSTEON:Using the WeatherBug Irritation Module

Irrigation Module's Settings

There are several variables that are adjustable by the user.

Irrigation Region - To adjust for the differing ET in inland vs coastal areas.
Absorption Factor/Soil Type - To adjust for the relative efficiency of soil absorption
Water Applied per Irrigation Cycle - The amount of water the user's irrigation program applies to the soil during each run.
Allowable Depletion - How much water will is allow to leave (be depleted from) the soil before the next irrigation cycle

Irrigation Module's Status Output

These variables are calculated from the WeatherBug data. They can be used in the program module for customizing the irrigation system.

Evapotranspiration - is an approximation of the amount of water leaving the soil via a combination of evaporation and transpiration
Irrigation Requirement - is the amount of water to be applied based on the accumulation of previous day(s) water deficits
Yesterday's Water Deficit - is the total amount of water that has evapotranspired during a twenty four hour window from the day before.

Irrigation Module's Commands

These are commands that can be used in ISY programs.

Irrigation - Cycle Complete - this command triggers the module's calculations for after water has been applied.
Irrigation - Reset Variables - this command triggers a reset of the module's Irrigation Requirement variable.

Program Example: Irrigate If Needed

The IF condition decides whether to water by comparing the Irrigation Requirement balance to a constant. The user is responsible for setting this constant equal to Water Applied per Irrigation Cycle, and updating it if they change the value of water that they apply per irrigation in their own programs.

If
        Time is 11:00:00PM
    And Module 'Climate' Irrigation Requirement >= 0.50

Then
        Set 'Front Yard' On
        Wait  10 minutes
        Set 'Back Yard' On
        Wait  5 minutes
        Set 'Back Yard' Off
        Irrigation - Cycle Complete

Calculating the Station Runtime

In order to replace the water that is lost from the soil your station runtimes will need to be properly calculated. Each type of emitter/sprinkler has a different amount of water that is being delivered per minute/hour. The calculator linked below can be used to calculate the appropriate runtime for each station.

Station Runtime Calculator

Initialize the Module

After you have installed the Irrigation Module the Irrigation Requirement variable will most likely will display zero. You will have to trigger a reset of the module variables to get things going correctly. Below is a walk-thru of the steps to perform this reset. Please note: If its the rainy season it may be difficult to tell if Irrigation Requirement is having an issue, so its recommended this be performed anyways just after the first install of the module.

In the ISY Admin Console go to the Programs tab.
Create the temporary program shown in the example below.
Right click on the program in the folder tree and select "Run Then" to reset the module.
Go back to the Weatherbug tab.
Check again Irrigation Requirement and you should now see a number instead of a zero.
Once you have done this initialization process you can delete the temporary program.

If
   - No Conditions - (To add one, press 'Schedule' or 'Condition')

Then
        Irrigation - Reset Variables

Forum thread: Proposed Evapotranspiration Algorithm in 3.1.4 Beta

ISY-26 INSTEON / ISY-99i Series INSTEON : How-To Guide