New user: flow rate questions

post by jpw94 on Apr 7, 2021

I have just installed Rachio 3. I also have a flow meter installed as well. I calibrated the zones and each of them are pretty high: 17.5 down to 11.5

Does the controller adjust water duration based on flow rate? When I set up a test schedule, it has it running for over an hour which means many thousands of gallons of water. I want to do things properly but I don’t want to have a second mortgage to pay the water bill.

Any suggestions on proper set up?

Thanks in advance.

post by rraisley on Apr 7, 2021

Duration is calculated based on Nozzle Flow Inches per Hour. Since you’ve measured the flows (I assume they’re 11.5 to 17.5 gpm), if you can measure or approximate the area of each zone, you can calculate the flow by:

Flow GPM / Area (sq ft) x 96.25.

Example: 11.5 GPM with 2,000 square feet: 11.5 / 2000 x 96.25 = 0.55 "/hour.

If you measure the areas and calculate each zone’s flow rate, enter it into Advanced settings flow, that will calculate each zone’s watering time.

post by jpw94 on Apr 7, 2021

WOW! I need to add those settings into my app!

Thank you.

post by ProWater on Apr 10, 2021

Yes, the basics.

post by fpuig on Apr 12, 2021

I have to do the same with mine @rraisley where under advance the calculation results needs to be entered? There is multiple settings there.

post by rraisley on Apr 12, 2021

My calculations above are for the Nozzle Flow Rate inches per hour, the last value on the Advanced screen.

post by fpuig on Apr 12, 2021

Could be possible to use the flow meter results for the GPM value?

post by fpuig on Apr 12, 2021

Just checking one of my zones, that I always believe its over watering, the zone is 634 sq. feet and the Nozzle inches is setting to 0.5 in.

The flow according to the Rachio flow meter is 8.6 gpm.

The formula results tells me that should be 1.30”.

No wonder why it was overwatered.

@rraisley this sounds right?

post by rraisley on Apr 12, 2021

That is right, per the calculations. It’s a good bit of water in a relatively small area, so I’d say go with it. Make sure you check your other zones; they usually won’t be the same.

post by fpuig on Apr 12, 2021

Thanks much for that info. I will re-adjust all my zones that I know are not properly adjusted.

In your experience the other values are ok with the default settings?

post by rraisley on Apr 12, 2021

If you’ve selected your crop and soil properly, I’d say they’re normally pretty good. Sometimes recommended root depth can be off, IMHO. And Rachio just has no way of telling how much water your system gets per hour, so doing a simple calculation can really help.

post by fpuig on Apr 12, 2021

Just re-adjusted all my zones and the new schedule time looks right with the default settings without needing to tweak them.

post by jpw94 on Apr 14, 2021

How do I know the nozzle flow IPH?

post by rraisley on Apr 15, 2021

There are 4 methods:

1. Use the Rachio default value for your sprinkler head type (least accurate IMHO).
2. Use the head manufacturer’s specs for your heads, allowing for pressure and distance range.
3. Do a test using Catch Cups (time consuming and results VERY dependent upon cup location).
4. Calculate from GPM used and Area being applied to (best AVERAGE method, does not tell about high or low water areas).

I use #4. Using your water meter, measure how many gallons of water are used during a given period of time (Total gallons used divided by minutes on) and Area in square feet for the area being watered (can be measured, use Rachio app with version 3, use Google Maps add-in, etc.), then use the formula above to calculate Nozzle Flow Inches per Hour (Flow GPM / Area (sq ft) x 96.25).