Very helpful. Just one question, is nozzle output per nozzle or total? Oh. One other- what is the .6234?
That’s collectively, at any 1ft x 1ft section of yard. Of course some parts of the yard may be slightly more, some slightly less, depending on how well placed and adjusted your sprinkler heads are.
.6234 is 7.481 divided by 12. There are 7.481 US liquid gallons in a cubic foot.
Or one could simple look up their sprinkler/nozzle manufacturer online and find what the nozzles put out in in/hr…but what do I know.
Yeah, what do you know? Sprinkler manufacturers rate their product by gpm per nozzle. This isn’t what the Rachio’s app is using. It’s using inches per hour collectively. Inches per hour requires square footage to calculate output.
Every nozzle manufacturer has the PR of their nozzles on their website these days…
Here are the nozzles I have in my yard. Shows GPM, GPH, and…would ya look at that! Precipitation in in/hr!
I’m not going to argue that PR calculation doesn’t require square footage, but the manufacturer has done it for you based on the radius of the nozzles reach (sq ft area), GMP, and sprinkler overlap (assuming a relatively well executed irrigation system).
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That is true, there are multiple ways to get the in/hr rate. First the nozzles typically have a screw that gets adjusted to tailor the radius, Also, there is overlap from head to head, and that is hard to estimate.
Easiest just average the GPM over the available square footage. If you have the flow meter that is more accurate IMHO. Then you are just assuming a uniform distribution. That should be reasonable assumption for a well designed system.
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That’s why if you are looking for more accuracy than just using the manufacturers spec sheet, you should just do a catch cup test. I think people would be surprised with how bad the uniformity of their system really is. I’ve resorted to readjusting my nozzles every spring to make sure I get the optimal overlap, as I’ve found that each year it can/will change. Also, replacing old nozzles has been a game changer in my aging system.
These figures are based on a consistent flow rate / pressure. I had to purchase a $124 pressure reducing valve to achieve this. Rachio’s app was no help in that regard and would be worthless without it. Again, their flow meter and software should be doing this calculation for us, as advertised. That was my argument throughout this thread.
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AT the end of the day, unless you have 1 zone per sprinkler head you’re going to have to go with the average, even if you sample with a catch cup.
The catch cup’s main value would seem to be in improving the overall uniformity.
True, but since its mostly a static value the workaround of manually calculating and entering a value does not seem to be to big a hill to climb.
Every sprinkler system I have owned has had its own pressure regulator. Most municipal supplies are way to high in pressure for a residential irrigation system.
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At the end of the day, Rachio already knows how much water my yard needs and can measure it via the flow meter and calculate watering time via my footage value. I already know my sprinklers are placed properly, equally spaced and adjusted properly. I don’t have a problem with uniformity, I have a problem with Rachio.
Probably not…but if it makes you sleep better at night. 
Like I mentioned earlier, most every nozzle on the market has less than a 10% difference in PR from 20psi to 80psi.