6. Determining Programmable Settings
Rain Bird
®
ET Manager Series - Installation and Operation Manual
44
ET Manager Settings
Information gathered in your site assessment should be
used to determine your programmable ET Manager
settings. The ET Manager settings consist of:
• Irrigation Control Settings
• Advanced Settings
• System Settings
Use your ET Manager Site Assessment Worksheet,
Appendix III, and the ET Manager Settings Worksheet,
Appendix VI, to program your ET Manager.
Irrigation Control
Soil type and rooting depth limit how much water the
soil can hold for the plants, and how much water the
plants can use. The type of plants used in the land-
scape affect evaporation rates. Together these factors
affect how often the landscape needs water. By evalu-
ating landscape conditions, you will be prepared to
enter accurate settings in your ET Manager.
Landscape conditions affect the following programma-
ble settings:
• Irrigation Amount for Valve Groups A and B
• Landscape Adjustment % for Valve Groups A
and B
Irrigation Amount
The Irrigation Amount represents how many inches (or
mm) of water is applied to your landscape during each
watering cycle. This amount of water evaporates before
the ET Manager will allow watering to occur. The
amount is based on your soil type and the plant’s root
depth (refer to Table 3). Because your landscape may
have different types of plants, your ET Manager has two
Irrigation Amount settings; one for valves in Valve
Group A and another for valves in Valve Group B.
Note:
The Irrigation Amount depends on soil composi-
tion, compaction, chemistry, temperature and plant
characteristics, etc. The above values are estimates,
and can be used as a basis for determining irrigation
schedules. If conditions change, the Irrigation Amount
should be adjusted.
When retrofitting your ET Manager to an existing sys-
tem, an effective Irrigation Amount setting can be esti-
mated based on previous watering habits. Determine
the average daily ET during the peak of the year.
Determine how frequently you watered during this
period, and how long the station run times were. Take
the peak ET rate and multiply it by the frequency of
watering. For example, if your average peak ET is 0.25
inches and you watered every other day, you would
take 0.25 and multiply by 2. Your estimated Irrigation
Amount is 0.5 inches. Make sure that the run times
scheduled in the sprinkler controller match those you
used previously during the peak of the year.
Landscape Adjustment Percentage (%)
ET is calculated with a short grass reference crop grown
in an “ideal” environment. Specific plant water needs
will vary depending on the type of plants and land-
scape conditions. The Landscape Adjustment
Percentage is used to fine-tune how much irrigation
water a landscape should receive. There are three fac-
tors that should be considered when estimating the
Landscape Adjustment Percentage:
I r r i g a ti o n A m o u n t
E s t i m a t e d I r r i g a t i o n A m o u n t ( i n c h e s )
R o o t D e p t h ( i n c h e s )
S o i l T y p e
2 4 6 8 1
2 1
8
S a n d
0 . 0 2 0
. 0 5 0
. 0 7 0
. 1 0 0
. 1 4 0
. 2 2
F i n e S a n d
0 . 0 7 0
. 1 4 0
. 2 2 0
. 2 9 0
. 4 3 0
. 6 5
L o a m y S a n d
0 . 0 8 0
. 1 7 0
. 2 5 0
. 3 4 0
. 5 0 0
. 7 6
S a n d y L o a m
0 . 1 2 0
. 2 4 0
. 3 6 0
. 4 8 0
. 7 2 1
. 0 8
L o a m
0 . 1 7 0
. 3 4 0
. 5 1 0
. 6 8 1
. 0 2 1
. 5 3
S a n d y C l a y L o a m
0 . 1 5 0
. 3 0 0
. 4 5 0
. 6 0 0
. 9 0 1
. 3 5
S i l t y L o a m
0 . 2 0 0
. 4 0 0
. 6 0 0
. 8 0 1
. 2 0 1
. 8 0
C l a y L o a m
0 . 2 0 0
. 4 0 0
. 6 0 0
. 8 0 1
. 2 0 1
. 8 0
S i l t
0 . 1 7 2
. 3 4 0
. 5 1 0
. 6 8 1
. 0 2 1
. 5 3
S i l t y C l a y L o a m
0 . 2 0 0
. 4 0 0
. 6 0 0
. 8 0 1
. 2 0 1
. 8 0
S i l t y C l a y
0 . 1 3 0
. 2 6 0
. 3 8 0
. 5 1 0
. 7 7 1
. 1 5
C l a y
0 . 0 9 0
. 1 8 0
. 2 7 0
. 3 6 0
. 5 4 0
. 8 1
Table 3. Irrigation Amount Chart