Zimmerman weather adjustment is useless

[shampeon]

I recently installed an OS 3.0 set up for 5 zones, 3 drip lines and 2 sprinklers for the lawn. I’m in the East Bay in Northern California, so having a controller able to adjust the watering levels based on temperature and humidity was a big selling point for me. Our rainy season ends in April, and we don’t typically get measurable rain until November. Due to evaporation, our irrigation schedules are run in the early morning.

With the Zimmerman default baseline of 66 degrees F, 0″ rain, and 30% humidity, using a nearby OpenWeatherMap location, I can watch the adjustment percentage rise during the day, but never go above 100% even when it’s been in the 80s and low 90s as it has been this last week. Then I watch it go down during the evening until it is down below 20%. When my zones are scheduled to run, at 4:00 AM, the temperature will be in the 50s so the adjustment is extremely low, and if my program runs at all it will be for a couple minutes at most. Usually the program is skipped.

Why is the Zimmerman adjustment calculation based on the current conditions when the program starts, and not, say, an average of the last couple days? Or an average of the highest value for the last couple days? If the forecast is for a hot day, and it’s been hot for the last several days, the fact that it is cool and relatively more humid at 4:00 AM doesn’t magically make my plants need less water.

Why is my adjustment percentage 87% on a day when it is 88 degrees outside, after an 89 degree day yesterday and 88 the day before?

FWIW I also opened a bug and put in a pull request to fix the California watering restriction threshold. The docs say it is 0.1″, but in the code it is 0.01″. That amount is immeasurable. The actual California guidelines are to turn off irrigation when there’s been 0.25″ of rain.

[Roger]

I am furious with what has happened to OpenSprinkler. I’ve been a customer for four years and OpenSprinkler has been “set and forget.” Now it’s useless. I’m in Colorado, and watering any time other than late at night is simply a waste of water. Between the wind and the evaporation rate, most of the water never makes it to the lawn. With the switch in weather providers, Zimmerman is completely useless, as shampeon pointed out. That eliminates one of the major features of OpenSprinkler, which I spent several months tuning for our situation. It took me several days to figure out why my expensive lawn was dying. I tested all the sprinklers, looked at the water level, increased the number of times the sprinklers ran at night, and the lawn is now a catastrophe. I woke up early this morning and noticed that the sprinklers were not running, but they should have been. The overnight temp was in the low 40s and the water level went to zero, which it has apparently been doing for a couple of weeks. I just spent a couple of hours reading the explanation in this forum, which makes logical sense, but the real impact is to make the OpenSprinkler device not worth much because I will have to do all the adjustments myself, probably daily. One of the great values of OpenSprinkler was that I could use the data from my own weather station via wunderground. I still have that access to that data, but OpenSprinkler no longer uses it. I want my money back!

[rjalex]

Well I still love my old 2.1 HW with 2.1.5 FW OpenSprinkler but yes I noticed a good while ago that the Zimmerman correction stuck at 10% without any variation due to changing weather station.

I noticed that in the “System -> Location” there was my old “pws:ILAZIORO38” wunderground meteo station (which sits on the building in front of mine be they always blessed 🙂 and I have used for years.)

I click on it and via the map chose my home address which has now changed to another known location. Submit.

Now the homepage shows the right meteo conditions and the watering percentage is back to something sensible.

Could you maybe have the same problem?

PS Why is it not possible to use the old Wunderground PWS meteo station names? The one I used is https://www.wunderground.com/dashboard/pws/ILAZIORO38 and still exists and works flawlessly but I cannot find a way to input its name anymore.

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