How can this be? Hunter solenoid.

Discussion in 'Irrigation' started by jcom, Jul 24, 2005.

  1. jcom

    jcom LawnSite Senior Member
    Posts: 791

    Zone runs perfectly when opening with solenoid. No good off timer. With new solenoid, all is well. New and old solenoid all show 17 ohms with meter. How can this happen? Making me crazy!!!! 24V at manifold
     
  2. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Posts: 2,781

    I can think of a number of possible reasons and I am sure there is a reason your old solenoid is bad. Just because the coil is good doesn't mean the whole device is good. A bad spring, trash, a voltage spike that magnetized the coil, and the list goes on. They are mechanical devices and as such will fail. The coil is only part of the device (it is also the part we see fail most often). This was much easier to explain back when you actually changed the coil out and the plunger and post were a seperate part of the valve. Anybody else ever play with the old 36V RB solenoids? I remember upgrading to 24V. We had buckner mechanicals, and you had to install a seperate transformer for the solenoids, but you had to keep the 36V transformer for the clock mechanism. We changed out one full controller at a time and kept the "good" 36V solenoids for repairs on the systems we hadn't upgraded yet. Ahh the good old days of in house maint. at the country club.
     
  3. jcom

    jcom LawnSite Senior Member
    Posts: 791

    Thanks for the info, WB.

    I thought the solenoids were good as long as the coil would read the right ohms. The old solenoid will only pull it part way open apparently and for whatever reason. I believe they have another one doing the same thing on
    a different zone as I could hear the flow different on one of the valves as I cycled through the controller. Hmmm!

    This is the partner property that I changed out a solenoid on two weeks ago. They have had three other of these solenoids replaced since the installation last autumn. All Hunter SRV valves and Hunter controllers.

    John ;)
     
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,004

    If this is that system with the undersized wire, you might take an ohms reading of the wire itself. Also, some, but not all, multimeters have AC current settings, which would allow you to see what a particular solenoid is drawing, in the system itself, by connecting the meter between the controller and the zone wire. An intermittent solenoid problem would take a while to show up, once it receives voltage, and warms up.

    A straight voltage reading, even in the valve box (unless the solenoid is connected) won't tell you everything, because the meter doesn't draw any current to speak of, so it doesn't duplicate field conditions.

    If you do see some resistance in the cable, and there is a spare conductor(s), connect the spare(s) in parallel to the common wire.
     
  5. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Posts: 2,781

    Curious now, are the solenoid wires red or black? Right before they switched to red wires, we had a LOT of solenoid issues.
     
  6. jcom

    jcom LawnSite Senior Member
    Posts: 791

    YES, THESE ARE THE PROPERTIES WITH THE SMALL WIRE. I WILL DO SOME MORE CHECKING. IF I NEED A DIFFERENT METER TO CHECK CURRENT DRAW, IT WILL BE IN MY TOOLBOX BEFORE DAYS END! I BELIEVE THERE ARE EXTRA CONDUCTORS SO WILL DO SOME MORE RESEARCH.

    THE SOLENOID WIRES ARE RED.

    THANKS FOR ALL THE HELP, GUYS.

    JOHN :rolleyes:
     
  7. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,004

    I haven't had to check AC current in years, since most of the troubled solenoids I switch out are obvious duds, but when I ran into a solenoid that wouldn't short out while I was looking (on an old electromechanical controller) I was able to find the one bad one by checking current draw. A lot of solid-state controllers have some functions to tell you about electrical problems.
     
  8. betterlawn

    betterlawn LawnSite Senior Member
    from MI
    Posts: 426

    If the problem is that it isn't shutting its not electrical at all. If this one works the way I'm thinking it does, than its a spring or plugged pilot port or something (like the first reply said I believe).
     
  9. jcom

    jcom LawnSite Senior Member
    Posts: 791

    I ASSUME THESE SOLENOIDS ARE NOT ABLE TO BE DISSECTED AND REPAIRED.

    I TOOK THE ZONE WIRE AND COMMON TOGETHER AND HAD ZERO RESISTANCE ON THE 1K SCALE. NO CURRENT READING YET! :rolleyes:

    JOHN
     
  10. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,004

    You could never repair a solenoid coil. It either worked or didn't. (Or it worked intermittently and drove you nuts) - Very old solenoids could have the coil as a removable assembly. I think Superior brass valves, and some high-end Buckner brass valves still have them. If 1K ohms is the lowest range on that multimeter, keep an eye open for another one, with a lower range. (although some digital multimeters might be good enough at the 1K range)
     

Share This Page