ET CONTROLLER NOTES PREPARED BY JAY O'BRIEN
Notes on my experience
with the SmartLine
SL1600 and SLW15 Irrigation
I purchased the system to conserve water and to take advantage of the
rebate offered by the City of Folsom. I purchased it from
PlumbersStock.com who offered
the best prices I could find. They were
quite easy to deal with.
When I first installed the SmartLine controller, the SLW15 weather
station was backordered as it was new and in high demand. I installed
the controller in place of my old controller and I set up a manual
program that matched my previous watering schedule.
When the SLW15 was received, I installed it and then spent time and
effort to change the parameters so as to match the previous amount of
water dispersed. Over time, I have recognized that was too much water.
I have now adopted the default and recommended values, with the
exception that I have changed the rain lockout delay, using the SLW DLY
function, from 48 hours to 24 hours. I will continue to monitor the
lawn and plants; perhaps as we come out of winter some modifications
will be appropriate.
I changed the rain delay from 48 hours to 24 hours so as to be able to
better monitor the rain sensor. Originally I had used the default rain
sense setting of 1/8", and after a rain it did not clear the rain delay
on its own. I then temporarily set the rain sense to 1/4", based on a
recommendation from Gene Johnson at WeatherMatic (SmartLine), to see if
it would actuate and clear on its own.
As the controller did not clear the rain delay, I requested and
received a new SLW15 weather station under warranty. The new one seems
to work as expected. I suspect the problem with the first SLW15 was a
defective lithium cell that experienced a catastrophic failure that
prevented the unit from notifying me of a low battery condition. At any
rate, it was promptly replaced by the supplier.
have learned that the sensor active LED, which changes from green to
red to indicate that watering is shut off with either rain (1/8" in my
case) or "freezing" temperatures lower than 37
degrees F, changes to orange, also indicating watering is shut off, for
an additional delay period after the rain sensor dries
out. However, in the case of a "freeze", the LED changes directly back
to green after a day of higher temperatures
without the additional delay.
The instruction book, along with the on-line references at SmartLine,
do a reasonable job of explaining the system. However, there isn't an
"Idiot's Guide", so my notes below will provide that functionality for
me when I will have to remember all of this in the future.
Perhaps my notes may be of use to others; permission to copy and use is
granted, with the understanding that the author (me) is NOT an expert
in this field and that I cannot and will not be responsible for
anything resulting from the use or application of my notes. My notes
are not intended to replace the manual; they are intended to provide
additional explanations that seem appropriate to me.
AUTO ADJUST MODE
Auto adjust initially does nothing until after it gets the daily
temperatures from the SLW weather station at 11:50PM and runs its
calculations at midnight.
Besides making the display show the correct time, this tells the
controller which day of the year it is using to calculate the watering
requirements. This is used, in conjunction with your latitude, by the
controller to determine how much sun you receive on that day.
PROGRAM START TIMES
SmartLine says if you are using a SLW weather station (auto adjust) you
should only have one scheduled run time. However, there is no down side
to scheduling multiple run times; NEXT RUN times shown at midnight are
divided equally across all scheduled run times. With our watering
regulations in Folsom allowing automatic watering from midnight to 10AM
and from 10PM to midnight on watering days, it is possible to use
multiple start times to spread the watering between the morning that
follows at least one not-watered day and the evening that precedes at
least one not-watered day.
ZONE RUN TIMES
Zone run times are used in STANDARD MODE, not in AUTO ADJUST MODE
unless the communication with the SLW weather station is interrupted.
ZONE RUN TIMES are not used by AUTO ADJUST MODE to determine watering
run times. Even though they are not used by the controller when it is
in AUTO ADJUST MODE, at least one ZONE RUN TIME must be set for each
zone to assign it to a program or programs.
DAYS TO WATER
Each program may have different days to water. It is possible to
schedule a program that contains only drip zones to run on any day or
every day of the week, as drip irrigation is permitted in Folsom on any
day of the week.
It is possible to omit specific times, days or dates from watering. I
haven't used this.
SEASONAL % ADJUST
This is not used when the AUTO ADJUST MODE is in effect.
This entry allows the controller to determine your position on the
earth between the equator and the north pole (latitude). From this the
controller determines how much sun you get on any day of the year. The
controller uses ZIP CODE to determine latitude.
This parameter tells the controller how much water is being
(precipitation rate) by the zone. The sprinkler nozzles and drip system
have specified precipitation ratings; for instance, my rain bird
nozzles with a water pressure of 30 psi are rated at 1.58"/hr. This
parameter can be specified for each zone either in inches per hour or
default sprinkler types can be selected that provide default values of
precipitation per hour, as shown in a table in the manual. This
parameter can be adjusted to change the amount of water distributed. If
the system is set to 1.5"/hr, the default for SPRAY sprinklers,
changing it to 2.0"/hr tells the controller that the sprinklers are
putting out 33% more water per hour, and the controller will reduce the
watering time by 33%. As an aside, unlike other parameter changes, I
have found that SPRINKLER TYPE changes take immediate effect, even
between midnight calculations.
This parameter modifies the watering schedule to accommodate the
of the plant type. This is what determines the run times, and thus the
amount of water distributed to a zone. The controller uses a "crop
factor" that modifies the calculated (100%) base watering number that
is correct for lawn mowed 4 to 6 inches tall. The "COOL TURF" selection
in the controller is 80%, appropriate for our average lawn mowing
height of 2-3 inches. The default values are shown in a table in the
manual. The water loss to be replaced by watering is different for each
SOIL TYPE and SLOPE settings are used to break up the watering into
short spurts to prevent runoff. CLAY, prevalent here, absorbs water
slowly, requiring watering and soak cycles. SAND, however, allows the
water to soak in almost immediately.
This is where we can adjust the watering based on localized
For instance, a zone continuously in the shade requires less water.
The controller uses the day of the year and the latitude to determine
the amount of sun expected (solar radiation). Every night at 11:50PM it
gets the high and low temperatures of the day from the weather station;
the difference between high and low temperature allows the controller
to estimate the humidity and apply that to its calculations. The PLANT
TYPE determines how much water is needed to replace that used by the
plant plus that which evaporates. The SOIL TYPE determines how each
watering cycle should be broken up, and SPRINKLER TYPE tells the
controller how quickly the system distributes the water.
If watering was not scheduled for a day or days, the calculated
requirements for the missed time are carried over to the next day and
added to the next days calculations. This handles the one and two dry
days imposed by the Folsom watering rules.
Rain and Freeze lockouts:
The weather station immediately notifies the controller when it has
detected rain or freezing. Either condition prevents watering while it
is present. After rain, a delay is imposed, 48 hours unless the
advanced functions RAIN DLY and SLW DLY are set otherwise. During the
delay, if the SENSOR button is pressed twice, it will cancel the delay.
The amount of rain needed to activate the rain sensor may be set to
1/8", 1/4", or 1/2". Freeze is identified whenever the temperature is
below 37F. The extra rain delay does not apply to a freeze condition.
Added clarification from SmartLine tech support:
-------- Original Message --------
Subject: RE: ET Controller notes: review request
Date: Mon, 15 Dec 2008 09:25:03 -0500
From: Johnson, Gene <firstname.lastname@example.org>
To: Jay O'Brien <email@example.com>
Thanks for your comments. Just one clarification. Regarding rain
shutdown, the hygroscopic disks in the rain sensor usually dry out in
12 to 24 hours after a rain. If the rain is several inches and the
weather following the rain the cool and cloudy, it might take 3 to 4
days in some cases. The SLW additional dryout period of 24 hours that
you have set, commences after the disks in the rain sensor dryout.
Therefore, the total down period could be 3 to 7 days. After the rain
event, the controller decrements all deficits and run times to zero and
it does not start to re-calculate deficits and run times until the SLW
dry out period has ended. So, there could be another day at the end of
the dry out before you have run times. Remember, that calculations only
occur at each midnight. So, you will have run times after the first
midnight after the end of the SLW dry out period.
The LED light at Sensor will be Red during the wet disk period. During
the SLW dryout period, it will be yellow. During the yellow LED period,
you can click the sensor button to move to Bypass which will be green.
Then click the sensor again to move back to Active and the Active will
go to green, ending the SLW dry out period early if you choose to do
Remember that the sensor LED also goes to Red when the temp is 37
degrees F or colder. It will go back to green which the temp exceeds 37
degrees. Any start time during the freeze period will be lost, so if
you have cold temps early in the morning, it is best to have your
watering start time later in the day.
H. Gene Johnson
3301 W Kingsley Rd
Garland, TX 75041
SmartLine controller and Weather Station: http://smartline.com
City of Folsom Water Conservation: http://www.folsom.ca.us/depts/utilities/water/water_conservation
City of Folsom iConserve: http://www.folsom.ca.us/depts/utilities/iconserve.asp
Irrigation Water Needs of Landscape Plantings: http://www.owue.water.ca.gov/docs/wucols00.pdf
California Irrigation Management Irrigation System (CIMAS) http://wwwcimis.water.ca.gov