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Congratulations on the implementation of the ET and PWS upgrades for the latest update. If I understand correctly the ET is only calculated for the day prior to the current watering cycle ? This seems to assume the watering cycles are daily. If you irrigate less frequently (say, once a week like I do) the weather adjustments become useless because of changes in the weather. We can have 20 degree C changes in max daily temp very regularly which has a big effect on ET. I assume that lots of users would have similar issues because of water restrictions limiting which days watering is possible.
Assuming the above is correct – what changes would be required to calculate the cumulative ET from the last irrigation cycle ? The change would require adding the daily ET values since a station was last used and calculating an average ET. Could this be implemented on the weather service, or does this need code changes for open sprinkler or both ?
You are correct that the current ET implementation results in one update per day, and it only uses the weather data from the previous day instead of accumulated over many days.
Part of the challenge of including more data is that the weather service generally charges more for access to more history data. We have never charged our users any subscription fee, so a big increase in weather service bill will be difficult for us to cover.
One possibility to avoid querying the weather service for history data is to simply cache the data locally on the controller. That way, if we keep the past, say, 2 weeks of data, that should be sufficient for ET calculation and won’t trigger additional charges. This is definitely possible, we just haven’t got around time to implement that.
Thanks Ray. To give you an example for the last few days watering adjustment has been around 110-120% with mild summer weather. Today its reached 200% on a very hot day, so it does make a significant difference. Is it possible a workaround would be to write a program which called the weather service for the Evaporation adjustment, then calculated the average and adjusted the watering percentage ?
For what is worth i have just bought my second Open Sprinkler, its a great product.You can always use the OpenSprinkler HTTP API to set the watering percentage from an external script. For example, you can write a script that runs a server to calculate watering percentage, and have it send HTTP command to the controller to update the watering percentage every day.
Yes i am aware of that, and in concept its fairly simple. Is there a way that I can access the ET calculation from your weather service scripts, rather than trying to do that myself ? The ET calculation is fairly complex and I’d like to avoid that task if possible. I am assuming I would need to locally host the weather service and call that to get the watering adjustment for the last day, then calculate the average correction since last watering after that ?
Our entire code base is open-source. The weather adjustment methods are here:
https://github.com/OpenSprinkler/OpenSprinkler-Weather
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