Advance Watering Calculations

I am new to Rachio as well as to the community. I am trying to figure out some of the parameters after my Rachio controller was installed. I live in Connecticut. I feel that this “Nozzle Inches Per Hour” should be dependent on 4 parameters: 1) how big is the area of the zone, 2) how many sprinkler heads are covering the zone, 3) what is the output of inches/hour for each of the sprinkler head, 4) the size of the area is each sprinkler head measured when measuring the output. Otherwise, there is no way to correctly calibrate the correct amount of time needed to cover the zone. Am I missing something?

Thank you for your response. But my question is that if you have 3 sprinkler heads covering a 500sqft area, you will have a different nozzle inches per hr than if you only have 1 sprinkler head for the same area even you do the cup test. For the same reason, 3 sprinkler heads covering 500sqft should have a different nozzle inches per hour than 3 sprinkler heads covering 1000sqft.

In that case you’ll need to put in an average or minimum or maximum rate — whichever you’re most comfortable with — since there’s no way to independently control each nozzle unless they each have their own valves. Ideally those nozzles in a zone would have matched precipitation (MPT series) to avoid this dilemma.

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You aren’t trying to calculate water usage with this field. You are just telling Rachio how much water each sprinkler puts down in a given period of time. Every nozzle manufacturer has data sheets showing the in/hr based on sprinkler setup, ie square or triangle spray patterns. This parameter will get you really close to your correct setting in Rachio. If you really want to fine tune it for your yard, then you need to do the catch cup test that @franz recommended.


@tmcgahey using your chart above for a single zone, square plot of grass with a 90 degree in each corner at 45 psi in a square pattern what calculation would you input in Rachio’s “Nozzle Inches Per Hour?” Would it be .45 or 1.8 (.45 x 4) or something totally different?

I want to know what Rachio wants us to put in Nozzle Inches Per Hour? Is it precipitation rate? Is it the total of how much each nozzle in a zone is putting out in the zone? Is it the average? You can see why there is confusion.

Thanks for any clarity you can provide.

BTW, tech support at Rachio cannot answer this question!!!

@SBelin, don’t overthink it. Precipitation is measured in in/hr, so yes, you just need to enter that value into the zone advanced section. In this case .45" is correct. You could make the case that you are trying to find an average precipitation rate if you have multiple arcs (90, 180, 360 degree) in your system. If you really want to dial in your precipitation rate, you need to do a catch cup test because in real life, you may have more or less overlap than ideal, giving you a higher or lower PR than a chart might show.