Weak zones and Maxi-Paws help needed.

Discussion in 'Irrigation' started by jcom, May 14, 2007.

  1. jcom

    jcom LawnSite Senior Member
    Posts: 791

    I posted a few days ago about a system that had all zones virtually inoperative. MaxiPaw all the way. 1" supply, 1" Dv 100 valves. 50 static psi. Thinking it was a flow issue, I put a stopwatch on the meter and just over 17 gpm available.

    #1 zone has 8 MaxiPaws and 1 1804 with a 8van nozzle. Total zone nozzles was at 20. Duh. I renozzled 4 of them, removing blue and installing reds. One RB was a replacement and had a green nozzle that did not appear to twist out like the others. Left that one alone. Replaced two black with a red. One had a red already.

    Now if the red nozzles are 1.8 gals., I thought they would work. Two worked fine. The rest would not rotate.
    I moved the spring as well.

    I repalced two of the inop RB's with the Hunter retros with #4 nozzles and they work just fine.

    Now the problem. This home has six zones with probably 40 Maxi's installed. After doing the above on zone 1 and the remaining 4 will not turn, what are my options? What am I missing? Should I keep trying to renozzle and then end up changing out the heads anyway?

    Am I going to have to change out all of the Maxis?


    Thanks all you RB folks.

    John:confused:
     
  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,997

    If the original nozzles were blues, and you replace them with reds or blacks, you also reposition the arm spring hook from the default position.
     
  3. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 22,063

    I know Boots has a soft spot in his irrigation (or any other) heart for impacts,
    but...hello???? those are water wasters; the seals leak, they rotate when you
    kick them..& then stick. Get the client ready to swoop into the 1980s. Gear-
    drives have proven their place.:hammerhead:
     
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,997

    For low pressures, though, nothing but a Maxipaw is going to cover the distance. No gear drive will throw over 30 feet with 25 psi at the head. The green nozzle would be a 9/64" Minipaw head, which is very close to the blue nozzle.

    Starting from scratch, I'd likely be using PGPs, in whatever quantity fits the job, even if I knew I could save on heads with Maxipaws. On an existing system, the option to switch away would depend on pressure and head spacing.

    The basic Mini/Maxi paw mechanism is fairly sound. In the absense of sandy soil, they can last a long time. I know my first install of Minipaws was over 20 years on the original heads.

    One situation an impact head fits, is when you have a stand-alone rotor on a high post. Gear drives don't have that splashing to drop water in the vicinity of the head.
     
  5. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 22,063

     
  6. Ground Master

    Ground Master LawnSite Senior Member
    Posts: 505

    Boots, at 25 psi the rainbird 5000 rotors are throwing 32' (1.5 nozzle), the 3.0 nozzle (actually 2.26 gpm at 25 psi) will throw 36' ..........very similiar to the maxipaw
     
  7. jcom

    jcom LawnSite Senior Member
    Posts: 791

    Thanks, guys for the info.

    I moved the spring when I changed the nozzle. I know that the design is seriously flawed and I am just trying to get the zones so they will operate. At the request of the seller of the property as he promised the buyer the irrigation system would operate. No guarantee as to coverage, but that it would operate. This is where I came in.

    So what I was doing was basically about all that could be done? Nothing major I was missing as to the operation of the RB's themselves?

    Do the Hunter retros just work that much better in a marginal zone? It would certainly appear that they do.

    This could get real ugly legally if we need to swap a pile of heads. For the seller if he refuses to ante up the cash for the upgrade.

    John
     
  8. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,997

    I'd consider the using black nozzles instead of the reds. Better low pressure operation. I still wonder what happened to make the whole system inoperative. Has there been a pressure drop in the neighborhood?

    As for the performance charts of gear drives, I take them with several grains of salt. I know for a fact that the Rainbird plastic impact will reach further at 25 psi than any gear drive, period.
     
  9. jcom

    jcom LawnSite Senior Member
    Posts: 791

    There may have been a pressure drop in the area. The new homeowner thinks there may have been a pump installed at one time. I could believe that based on the plumbing at the POC. But it is not there now.

    Any kind of booster pump that would help me out in this application?

    I thought the RB's would operate with the pressure we had.
    the longest zone run is maybe 150'. Maybe the cumulative total psi loss with so many heads on the zones?

    Why would a higher flow nozzles operate better than a lower flow with the pressure we have, WB? Oh yeah, WB, I think you have forgotten more irrigation stuff than I will ever learn. What an encyclopedia you are. Thanks.

    Thanks for the input.

    John
     

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