New Zone, Double the irrigation time! Why?

[rraisley]

@4puf

I am not a sprinkler system engineer but to me “Nozzle Inches per Hour” is a very confusing definition. What if I have multiple sprinklers covering a certain area? Do I add each unit in/hr numbers? What if the surface is much bigger? or smaller? Anyway, I believe what Rachio means for this field is the “precipitation rate” which should be calculated by using catch cups placed in the zone. I haven’t done this yet but I will soon.

I’ve used catch cups. They’re a pain in the butt. In fact I’ll send the ones I have to anyone that want’s them if they pay postage. The reason I don’t like them is the results vary SO VERY MUCH depending on the location of them. Move them a couple feet one way or the other, and get a completely different result. Yes, my sprinkler flow isn’t even, and these tells you that, but it can be so very different. I prefer to simply (for me, at least) measure the total water flow to a zone for a given time (using the water meter), to calculate total GPH to the zone, and measure the area of the zone being watered, and calculate that to a final Nozzle Inches per Hours, as you have correctly done.

“Precipitation Rate” may be more understandable, but this isn’t really precipitation, it’s irrigation. Maybe Irrigation Rate?

For now I came up with a Precipitation Rate (in/hr) of 0.46 by entering my rotor head manufactured provided 3 GPM and the irrigated area of 630 ft^2

Well done on the calculation! Seriously, most people have no idea how to do this! But do you have only a single 3GPM rotor head that irrigates that entire 630 ft^2? You are absolutely correct that if that 630 sqft zone has a total flow of 3GPM to any and all rotor heads, then the Precipitation Rate would be 0.46 "/hr.

Why would a rotor head be 1" per hour? wouldn’t this number change dramatically based on the set throw and the angle covered?

I think they have used standard tables of manufacturer’s sprinkler head types, which usually have spacings and such and total "/h rate based on that. My experience is that most installations are not done to the book, and usually provide less water than the manufacturer (and Rachio) intended.

As you can see I am very confused about all these numbers and to me they make no sense because some should be absolute number, like in a fixed nozzle head and some other relative numbers like in a rotor head. I think the Rachio App should only be asking one information which is how much water is deposited on the lawn in a certain amount of time, that’s it, no area, no sprinkler type, no number of heads.

They kind of are asking that, in the Advanced settings, with the Nozzle Inches per Hour, but I agree that the terminology isn’t great.

Anyhow, thank you for providing the calculation. That makes things so much clearer! As you guessed zone 6 and 7 are identical and all the numbers you used in the formula are exactly the same for both however zone 6 gets half the time of zone 7

Probably you are right that there might be a bug or there is a manual time setup somewhere, can you help me find the manual time setting? I looked everywhere in the App but I can’t seems to find it.

It’s not very intuitive. You enter all this fancy information for Rachio to calculate times with, and it tells you the times, but then you can go to the Schedule and change all the times manually. Once that’s done, IMHO, no zone changes will change the time. The schedule uses the calculated time, unless you change it, then it always uses the time you entered, but doesn’t warn you about it. I would create a new Schedule with the zones that you want. I think you will find similar zones to have similar times that way.