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Ed in WI



Sunday, May 3rd 2015, 6:09pm

low pressure on just some rotor heads 1 zone

I have had Hunter I-20 rotors installed for 6 years now. I have a 5 zone system with 4 rotors on each zone. Last summer I noticed that in zone 5 my number 4 rotor wouldn't pop up on it's own. When I manually pulled it up the pressure on rotors 2 and 3, along with 4 would decrease. Rotor 1 always has full pressure. If I plug any of the 4 rotors the other 3 have full pressure. As soon as I open up all 4, rotors 2, 3 and 4 have low pressure. Rotor 1 sprays like it has since day 1. I have replaced the solenoid, and diaphragm (Hunter PGV 100 Jar Top). I have dug up rotor 4 and cleaned what I could to see if there was sediment in the body.
I have a well system and no way to see if I am using water with all 4 rotors shut off and the system on to see if I have a cracked pipe. If it is a crack it must be small because I can never seem to hear our water pump cycle on telling me the system is using water when it shouldn't be. I have very dense soil and have yet to find a soggy spot in the yard.
All my sprinkler installer tells me is I have a rock in the line. I haven't dug all 4 rotors up yet to flush each one but did flush number 4 when I had it removed.
What else can I trouble shoot before digging up each head and what to look for when I do? My thought was the rotors were getting plugged with sediment but that would defeat the reason why they spray fine if one is shut off.
Any ideas will be appreciated. Thanks.


Supreme Member

Posts: 5,306

Location: Metro NYC


Sunday, May 3rd 2015, 6:46pm

Get some plugged nozzles and install them in place of the existing ones, then run the zone and look for a leak.

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