ET Site Information Overview


To simplify setting up a Hunter ET System we've highlighted some of the more complex choices.

Note: The ET Module dial must be left in the Automatic position, or the ET program will not irrigate! If the ET System is watering, moving the dial from the Automatic position will cause it to stop.


Plant Type                                                             

At the Plant Type dial position, select and customize the actual plants irrigated by each zone. There is one screen for each zone (if there is more than one plant type within a zone, select the type most sensitive to watering).

Set all information for one zone (or station), then advance to the next station with the Station button on the ET Module. Use the right arrow key to advance through the fields, and the +/- buttons to scroll through all possible selections.


There are only two maturity settings for all plant types, NEW or

Established indicates normal watering requirements for turf or plants. New indicates adjusted watering for the higher needs of growing plants which do not yet have established root zones. The New setting will automatically change to “Established” after a preset period of days, depending on the Plant Type selected. If a plant type is entered as “New”, the starting crop coefficient will “mature” over time to an established plant crop coefficient based on the plant type:

• Grass: 42 days (6 weeks)
• Shrub: 3 months
• Tree: 7 months
• Annual/Perennial/Biennial: 30 days
• Native/Desert: 6 weeks
The setting can also be changed manually at any time.


Selects the general plant type, from a table of choices.

The Type setting selects the general category of plant, based on groups defined in WUCOLS (Water Use Classification of Landscape Species). This important setting will tell the system the plant's characteristics including the depth of the root zone, and the sensitivity of the species to watering. It combines with the Variety setting to create a crop coefficient (Kc) as well as root depth and other factors.


Selects the exact, or similar, species under Types.

If an exact plant is not represented, there are two options:

1) Choose the closest type, based on the plant’s watering needs. This is generally adequate.
2) Customize one of the existing plant types. This is described in detail below the plant type table.
For further information on regional plant data, consult an agronomist or regional county extension office.

NOTE: The included plant types are based on recognized categories of plants, by watering needs. The plant type choices in the ET System are representative of the different levels of watering requirements of typical plants, and are based on the Water Use Classifications of Landscape Species (WUCOLS) Guide developed by the University of California (available on the internet from the California Department of Water Resources).

Site Info

At the Site Info dial position, select and customize the slope, soil, and sun exposure for each zone of irrigation. There is one screen for each zone (if there is more than one condition within a zone, select the type which predominates).

Use the arrow keys to advance to each value, and the +/- keys to cycle through the choices.


This value (along with SOIL) is used to determine automatic cycles and soaks for each station, based on the probable run-off of irrigation. Use the +/- keys to set the percentage of slope, from 0 to 50% in 1% increments. If the ground is flat, leave this setting at 0%.

Determining the slope percentage: The slope is defined as the amount of elevation change, or Rise, divided by Run (the measured distance), multiplied by 100. If an irrigated area rises 2 (feet or meters) over 15 (feet or meters), the slope is approximately 13%: (2/15)x100=13.333.


Soil type (or texture) is used together with the SLOPE information to determine the Intake Rate of the soil, resulting in cycle and soak scheduling. Use the +/- key to select from the following soil types:

• Sand: Predominantly Sandy soil
• Loamy Sand
• Sandy Loam
• Loam: Predominantly loamy soil
• Clay Loam
• Silt: Predominantly silt soil
• Silty Clay
• Clay: Predominantly clay soil

Soil type is also used to determine the water holding capacity of the soil, and is important to the soil moisture calculations.


Sets the average amount of sunlight for each irrigated area, according to the following values:

• Full Sun – 100 percent of solar portion of ET
• Part Sun – 75 percent of solar portion of ET
• Part Shade – 50 percent of solar portion of ET
• Full Shade – 25 percent of solar portion of ET

The ET System is equipped with a solar radiation sensor and measures daily sunlight (this is why the ET Sensor platform is mounted in full sunlight). However, the irrigated areas may be in a variety of different sunlight conditions, and this setting provides an offset for the sun measured at the sensor, and the sun which probably reached the plants in a given zone. Zones are assumed to be in full sun, unless you enter a different setting here. Set the SLOPE, SOIL, and SUN for each station. Advance to the next station with the station button. When all stations have Soil Type data entered, turn the dial to save the information. For initial setup, proceed to the Sprinkler Type dial position.

Sprinkler Type

At the Sprinkler Type dial position, select the type of sprinkler which irrigates each station or zone. This setting determines the Precipitation Rate for each zone, which is a critical setting in determining the Run Time for each station. Use the arrow button to navigate to the Sprinkler Type under the station number, and use the +/- keys to choose one of the sprinkler types available (or create a Custom type).

To simplify setup, several standard types of irrigation devices are included, along with typical precipitation rates. Select the type closest to the irrigation for the zone.

• Rotor – 0.5 in/hr (12.7mm/hr)
• Spray – 1.6 in/hr (41.3mm/hr)
• Drip – 0.35 in/hr (8.9mm/hr) (this can vary widely and should be checked for
• Bubbler – 1.16 in/hr (29.46mm/hr) (this can vary widely and should be checked
for accuracy)
• Custom – entered by user (based on field tests)


The Precipitation Rate is specified in inches or millimeters per hour. The Precipitation setting is based on the Sprinkler Type and cannot be changed directly, except when “CUSTOM” has been chosen. The longer a station runs, the more inches or millimeters it adds to the root zone of the plants. ET determines how many inches or millimeters were lost; Precipitation Rate determines how long the station needs to run, to replace the lost water. Sprinkler types should not be mixed within a single zone.



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