I’m getting my new Rachio 3 configured with an older irrigation system I inherited when I bought my house. In Advanced Settings for each Zone there’s a Nozzle Inches Per Hour field which has a very large effect on Rachio’s Flex Daily schedule calculations. I’ve read a few posts here about this field with conflicting information, so I’m hoping someone can clarify its exact meaning.

If it’s some specification of the actual nozzle in the sprinkler head, I don’t think I have much hope of getting an accurate number. As I said, this system is ancient and there’s likely a mix of older and newer parts that have been replaced over the years.

I do have a set of rain gauges (little plastic cups that you stick into the ground), that measure inches of water. So I can use those to estimate inches of water going down per hour in a zone by taking the mean amount collected by each gauge. My question is, does this equate to the intended meaning of “Nozzle Inches Per Hour” in Rachio’s settings? Or is there a better way to estimate it?

YES! Throw those around your zones and measure the amount of water at each one. I’d follow the instructions from Orbit on how to do a catch cup test. You can enter it into the calculator on the Orbit website to figure out the inches per hour and the efficiency of the zone.

What I will say is that if the system is a hodgepodge of mixed sprinkler and heads, you may find horrible efficiencies. It is a fairly cheap option to go through and at least replace the nozzles with the same manufacturer and model. Getting as uniform and efficient as you can with the watering will be extremely helpful with the success of Flex Daily!