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Starting Member


Wednesday, July 26th 2017, 8:43pm

New system has two zones with low pressure

Hey folks! Really happy I stumbled on this site. I am looking for some ideas here. Pretty stumped at the moment.

The system:
I expanded a 3 zone system to 9 zones. To do this, I added the following two pre-built manifolds:

Using a new Rachio Gen2 16 zone controller.

All piping and joints for zones 4-9 are brand new 3/4" flex pipe.

The supply line from the house water main is also 3/4". My house has a steady 80psi.

The problem:
2 zones are for garden areas, the remaining zones are for my lawns (front and back between all of them). Each zone for grass has 6 or less fixed spray head sprinklers (Orbit brand again).

Zones 5 and 6 have about half the pressure the others do. None of the heads on either of those two zones pop up all the way, or spray their full range like the others.

Attempts made to fix it:
1) I swapped solenoids out between a full pressure zone and zone 5. No change. So, not a solenoid problem.
2) Replaced diaphragms, no change.
3) Inspected the valve housing, no dirt (shouldn't be it's brand new!), nothing of significance.
4) Manually turning the solenoid on gives the same low pressure. So with the above it does not seem like a valve problem.

What else can I try?



Supreme Member

Posts: 482

Location: Houston, Texas


Thursday, July 27th 2017, 8:44am

Its probably a flow problem
You may have too much water flowing through the the 2 zones that are giving you the problems with pressure.
Think of it like a garden hose with a couple of holes in it, you will have too much water flowing out the holes and not enough at the end of the hose.

If you exceed the capacity of your 3/4" line, Probably 8-10 gallons per minute, you will have very poor performance.

If that sounds like a reasonable explanation you may either want to split the zones into more zones or find a way to reduce the flow with water conservation heads like the Hunter MP Rotator or the Toro Precision Series Spray Nozzle.

Good Luck
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