OpenSprinkler Forums Comments, Suggestions, Requests Weather Adjustments?

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    I’ve seen numerous threads about weather adjustments and not sure where this landed as the threads span numerous years and firmware revs- need a sticky maybe, not just explaining how these work in “theory” but how to fix the obvious issues. Because of course they sound cool. But don’t’ seem to work.

    I’m using the ETo version which I took as an evaporation rate model; versus the more complicated Zimmerman which seemed broken according to many people. Well the weather adjust seems to go to 0% at night when I have my zones set to water, then of course 150% in the afternoon when no sane person would water. Thought all sprinklers are supposed to operate at night due to efficiency? Anyway, my soil is now as hard as concrete because I can’t get the system to work with the weather adjustment enabled. My tall fescue lawn is almost dead due to this “issues” or feature depending on how you look at it.

    That being said. Do any of these “weather” adjustments work or are these more of a marketing gimmick. Not being snarky, real questions. If it’s 65F at night outside and it hasn’t rained in 5 days I need to water because it’s 90F+ during the day and water just vanishes. Thought this system could handle that?

    Do I need to tweak the Baseline ETo(In/Day)? If so which way to adjust it? Up I assume, right now it’s at .16in/day. If I go higher will the system put water out and do what it’s supposed to do?? I need to get at-least an inch of water per week on my grass and I’d like to adjust for any rain that may occur and evaporation rates or pop up rain. Is that even possible with this system?? I mean I know exactly how long to run each zone to attain a given accumulation. So do I just have install a dumb rain sensor and forget about the fancy technology in this system???



    If you present the same data to 5 different gardners, chances are they will tell you 5 different things and they all think they are right. The weather algorithm is just an algorithm, it’s not human intelligence, it can’t read your mind. That’s why you are given parameters which you can tweak to fit your own specific need. You can’t expect it to work perfectly with the default settings. I think your expectation is too high.

    “150% in the afternoon when no sane person would water” — I don’t think everyone agrees on that. If you don’t want it to water in the afternoon, then just not schedule a program in the afternoon. As I said, the algorithm can’t read your mind, but there is enough flexibility in the firmware that you can configure it to better fit your need.

    That said, if you observe the watering percentage change during a day (sounds like you do, since you mentioned 0% at night and 150% in the afternoon) — then perhaps you are hosting your own weather server? If you use the official OpenSprinkler weather server, it uses caching so the watering percentage during a day does not vary.

    About ETo: yes, of course you should tweak the ETo. That’s mentioned in the support article that explains the weather algorithm:

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OpenSprinkler Forums Comments, Suggestions, Requests Weather Adjustments?