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Starting Member

Posts: 1

Location: Delaware


Monday, August 27th 2018, 8:25am

Well pump capacity and zone design

This is a Rainbird irrigation system that was already installed at the home we purchased. The irrigation system uses the same well/pump as our house water. The pump is a 10 gpm and the tank is designed to activate the pump when it drops to 30 psi. So, except at the start, the irrigation system is basically operating at 30 psi. 8 of the 9 zones are standard rotary heads and they are configured to be less than or equal to 10 gpm. The 9th zone is a mix of two (2) 1800 15-VAN and four (4) 18-VAN heads. When that zone comes on, it starts fine but within 2 minutes is dribbling. Using the Rainbird spec sheet, the 15-VAN @ 180 arc @ 30 psi pulls 1.85 gpm, and the 18-VAN @ 180 arc @ 30 psi pulls 2.66 gpm. The total of the 6 heads is 14.34 gpm. They are all configured to reduce the spray distance, but Rainbird techs said that does not reduce the gpm.

First, does my analysis sound right? Second, is anyone else having this problem? Third, and most important, what suggestions do you have to address the problem (I'm trying to avoid the cost and hassle of running a 10th zone).


Active Member

Posts: 42

Location: Washinton


Sunday, September 2nd 2018, 5:10pm

Sounds like you definitely have a flow or volume problem. It sounds like your system can not keep up with the demand of the zone.

The good news is, there are alternatives. Rainbird's VAN nozzles eat up more water than the standard Rainbird nozzles. Although when you compare the standard nozzle spec sheet to the VAN nozzle it appears they put out the same amount of water.

As an alternative Rainbird has the RVAN line, which is basically a Rotating Van nozzle and puts out about half the water as a standard van nozzle and can be found here.

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