“ETO Adjust Factor” Off Target WaterSense Algorithm
Topic: “ETO Adjust Factor” Off Target WaterSense Algorithm
I am currently experiencing WaterSense Algorithm problem with the RainMachine HD12. I have watering times set to adequately water during the summer’s peak. However I am now over watering as we come into fall and I expect the same next spring. I know WaterSense should be smart enough to compensate for seasonal adjustments but in our area it doesn’t do it very well. It is a pain to individually decrease each zones time every spring and fall and increase in before the peak of summer.
I base this request given my six years of experience and knowledge of the RainBird ESP-SMTe controller which is also “EPA WaterSense Certified”. The RainBird ESP-SMTe controller has a setting; “Special Features / ETO Adjust Factor” that would allow a custom setting for the seasonal watering. Settings that are “off target” from WaterSense algorithm. It would universally readjust all the zones run times with one setting, ETO Adjust Factor. This worked quite well.
I had the misconception that the RainMachine HD12 “Hot Days” setting might accomplished this. It does not. As explained by RainMachine; “The hot days algorithm has to do with a jump in temperature. So if ,normally, it would be 80 degrees that time of year and it jumped suddenly to 90 the machine knows that this larger differential change throughout the day will increase the amount of evapotranspiration occurring. The machine will then water more then it normally would to maintain the moisture levels in your soil.”
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I agree, when September rolls around I have to make manual changes to avoid over watering. I find that in my area daily summer watering simply works best for consistency and avoiding long make up sessions from a 3-4 day a week schedule. But by time I get to September however my Rainmachine does not make sufficient adjustments to water less and I have to scale it back myself. I would love to keep it on a daily schedule during Sept-Oct and have the machine know when enough is enough or to change from daily to every other day on its own.
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Yes! There should be an ETo Adjust Factor on the RainMachine unless they have a better solution. We have been experiencing much colder night temperatures and longer shade time. The grass roots need to dig in for the winter. ETo Adjust Factor is merely offset for the ET value used for calculating run times. Presently the only other RainMachine solution that I can find is to either
- Manually calculate run times reduction and enter zone values individually or,
- Change the soil type to one with more field capacity to universally change zone run times.
(field capacity table at https://support.rainmachine.com/hc/en-us/articles/228001248-Soil-Types)
FYI: Rain Birds definition for the ETo Adjust Factor setting: Fine-Tune Watering
[If minor adjustments are required to calculated run times, you can increase or decrease run times for ET zones by a selected percentage. These adjustments will apply until you set the value back to 0.
The Fine Tune % By Zone value can be adjusted from -60% to +60%. For example, if a +50% adjustment is set, then a calculated run time of 10 minutes will become 15 minutes.]
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Agreed - Currently I have three different programs. Spring, Summer and Fall - turning/switching them on/off when the season changes. This fall I am going to play around with 'Crop Coefficient' settings for the 'zones' different for each month. In theory lowering this in Spring and Fall should work.
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The weather adaptive watering is set for Your program types? That should take care for most of the spring-summer issue (exp. if et0 is 10mm in summer and 5mm in spring Rainmachine will irrigate ~50% of the set value in spring). To see how ET changes over the year You can take a look at the Settings/Wather tab to ET and Seasonal ET adjustments.
However there are cases where it is necessary to have monthly values for plant coefficient - most notable are the crops which have different water needs on different phases of their growth. You could use that at custom plant settings - I don't recommend using too low values since there is already a reduction of irrigation amount due to low ET's at spring vs summer but You can set 12 values for the 12 months of the Year.
If You don't know what to set for the rest of the values just use our preset ones:
You can experiment with the rest of the values too, root depth and crop coefficient lists are existing on the internet so any kind of custom setup can be met.
There is a good list for plant coefficients here on Table 12: http://www.fao.org/docrep/X0490E/x0490e0b.htm
And rooth depth list in Table 22 here: http://www.fao.org/docrep/X0490E/x0490e0e.htmBut be careful and check Your irrigation's a few weeks if You set different values since both values will influence heavily how much irrigation will be done and how much rain can be "stored" in the soil.
Hope this helps,
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For now I am following Jeff’s idea and have installed 6 new programs that reduce the zone watering time in 10% increments (keep it simple). In the future I may try and implement the solution you propose. Sure would be nice to have two RainMachines and compare the algorithm results using crop coefficient setting or soil capacity.
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