Sprinkler Update

So I got two free timers from Orbit after I called them.

I hooked up one of the new ones, and it still doesn’t work. There is supposed to be 24VAC at the terminal when it’s running, and the voltage is zero. Just to be sure, I checked the resistance on a couple of the solenoids, and it’s about 70 ohms (the reactance is no doubt quite a bit higher on AC). But clearly, if there is no voltage at the terminal, the solenoid isn’t going to open. I went to the Orbit site for troubleshooting, and it says that if there is no voltage at the terminals, the timer has to be replaced…

At this point, I’m wondering if the system is haunted.

[Update Saturday evening]

People commenting, go back and read the original thread. I’m not clueless. I’m pretty sure that if there was a short to ground, I’d see it when I measured the resistance on the solenoids.

[Noon update]

OK, it finally occurred to me to check that it was getting 24VAC input. It wasn’t. The upstream GFCI had tripped and the transformer wasn’t outputting…

One of the ones I took off had an indicator saying “No AC,” but I swear I didn’t see that when I was working on it. I now have five of them, four of them (AFAIK) functional. I’ll return at least three to Home Depot (since that’s how many I bought there).

[Update a while later]

And yes, I was a dumbass.

18 thoughts on “Sprinkler Update”

  1. Assuming you know how to use your test equipment here, so….

    Put a fuse inline with the load terminal from the solenoids, I bet you have a short to ground and that is why you don;’t have voltage at that terminal.

    Alternatively, put a couple of 12 v automotive lamps in series and use them to test the timer. See if they light when the solenoids should be energized (unhook the solenoids). See if it is the timer or the load.

    Another way is to hook the 24 v supply across the solenoids (bypass the timer) do they work then?

  2. Try plugging the solenoids directly to the 24 AC supply to see if the sprinklers come on. Do this whenever the lawn needs water. ^_^

  3. People commenting, go back and read the original thread. I’m not clueless. I’m pretty sure that if there was a short to ground, I’d see it when I measured the resistance on the solenoids.

    Dunno the original thread might say otherwise.
    Well you wouldn’t see the short if there a shunted capacitor in the microfarad range though that be very unlikely, considering there should only be cable and solenoid coils in the system.
    Did you check if your multimeter can read the 24 VAC from the transformer?
    The 60 ohm resistance might even be a little high considering the solenoids inductance.
    You didn’t try to put a different 24VDC power supply in your last go around?

  4. Good morning, Rand,

    It kinda depends on what is meant by “short to ground”.

    If the solenoids are themselves short-circuited, then you have a “short to ground” in the sense of one rail of the power supply being shorted to the other rail.


    **IF** (and these are definitely “ifs”) …
    1) one rail of the supply is tied to an earth ground (think “ground rod driven in the earth”);
    2) the solenoids have developed some sort of insulation-failure where the current is “leaking” out of the solenoids and into the earth;
    … there’s your “short to ground”.

    I can’t imagine that the timer is this finicky, but I see it all the time with in-the-pavement vehicle-detection loops — those rectangles you see in the pavement when you’re sitting at a traffic-light. A mass of steel sitting above the loop changes the inductance of the loop, which is sensed by a loop-detector, which in turns closes (or opens) a switch to signal the traffic-control equipment to perform some action.

    The insulation of the loop from ground should be somewhere above 100 megohms. If the insulation degrades, and the resistance falls into the neighborhood of 5 to 10 megohms, the operation of the loop and loop-detector becomes erratic, and the loop has to be replaced. (Happy happy joy joy. NOT.)

    Like I said, I can’t imagine your timer module is somehow finicky about grounding, but it’s worth checking out. The suggestion by “B” is definitely worth trying — if it works with the 12-volt lamps, but not with the solenoids, the problem is in the solenoids or in their lead-in wires.

    My two cents’ worth.

    Hale Adams
    Pikesville, People’s Democratic Republic of Maryland

    1. There is no measurable voltage at the terminal with no wires attached. There should be 24VAC on the meter, but there is not. It has nothing to do with grounding.

    2. It’s a sprinkler system, so I’ll assume all the insulation is good. Sometimes there can be bizarre (and dangerous) problems if a house’s water supply and ground aren’t done properly, and the valves are pretty much an interface between AC and the water system. But since that is so common, there’s no way the solenoids would be using their frame for any part of the circuit.

      Plus, if I recall correctly, he had a solenoid on the table and it doesn’t work either, though it could be hard to tell if it’s working if it’s a pilot operated valve without water pressure applied. Still, it would represent a proper electrical load and he should read 24 AC on one of the outputs, and it’s not working even without any possible electrical path through a water system.

      Triac outputs sometimes have trouble turning off under no load (due to leakage current), but his problem is that they’re not turning on. Even if they only turned on for half the AC waveform, he would see voltage on his meter. If his meter, in the same configuration, can show 120 VAC on an outlet, then the meter is good, too.

      We went over most of the other “duh” type problems in the other thread (not making a good electrical connection to the output, bad meter, etc), so perhaps it is a bad batch of hardware, a bad firmware revision, or something odd about the programming.

      Although there are variety of alternate solutions, such as using a cheap electro-mechnical lamp or aquarium timer to run the 24 VAC power supply and use that to directly run the sprinklers, or ordering an output board for his PC so he can run the Sprinklers as a Linux daemon, he would still have a bunch of possibly perfectly good and quite nifty electronic timer units that would continue to bedevil him.

      One of my friends in Florida suggested calling a local lawn sprinkler guy, on the theory that they’ve seen everything under the sun.

  5. You should perhaps figure out why your GFCI tripped. Those exist for a reason.

    Also, before you go returning your extra sprinkler controllers, remember all the poor people in Somalia who don’t have sprinkler systems for their gardens. Ask yourself “Can I make a difference”?

    Or perhaps act more locally. What if you used the controllers to make an even fancier sprinkler system for your yard, or perhaps used it to control the crossing gates or switch yards on an elaborate HO train set that represents California’s high speed rail system? Heck, even controllers with dead outputs should work great for that, so you’d be way ahead of the game.

  6. Okay a little confused now how the computer/display on the timer worked if the GFCI on the plug with the transformer was tripped. They have a separate battery to run the computer/display?

    1. Orbits uses a CR-2032 coin battery (at least in the video I watched) so it can remember the time through a power glitch. They say the battery should last a number of years. Obviously the system can run off the battery or it wouldn’t have an indicator saying there’s no AC power.

  7. Find out why the GFCI tripped.

    That (generally) indicates a pathway for current to ground (or somewhere else). It might be the transofrmer, or it might be the whole system is referenced to (earth) ground and there is another path for the 24 VAC (like the wiring to the actuators….usually buried underground).

    1. It could have been lots of things; it happened weeks ago. It hasn’t done it again since I turned it on. If I’d been using that circuit for anything else I’d have noticed the problem and just reset it without all of this sturm und drang with timer replacements.

  8. Oh, and don’t be a jerk when asking for help.

    Not checking the transwformer is a rookie mistake, and your sttement led many of us to go in a different direction, assuming that you had a clue as to what you were talking about.
    Sorry if our attempts to help irritated you after you asked for help.

  9. Rather amusing to follow along to the conclusion and a good example of the fallibility of smart humans.

  10. I think this is at least the second time you posted that an electrical problem was fixed by an upstream GFCI (the first one was an obscure GFCI you didn’t even know existed in the house at the time, I think).

    I’m sure I’ll forget by the time your next electrical adventure starts, but hopefully someone else in this thread remembers to ask if you checked all of your GFCIs the next time you post with an electrical problem.

    Glad you were able to get it all sorted out!

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