OpenSprinkler Forums Hardware Questions Choosing the right coil

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    Hi, I am trying to figure out how to replace a relative small residential irrigation system (currently I use two independent hose timers) with opensprinkler. Most of the time the mains water pressure runs low (that’s why two timers).

    So, initially, I thought that a semi-direct solenoid valve (assisted lift) would be a preferable choice (operating range 0-10 bar). When I requested the power consumption from the manufacturer I got back “inrush power (24vac coil) is 44VA, the holding power is 10W” which was a bit of disappointed. 44VA/24V=1.83A means it’s above the capacity of OS AC version (800mA). Although DC version can handle much more current (3 amp continuous and 30 amp impulse current) probably 9vdc is not enough to drive this solenoid.

    Finally, after a lot of searching, I found one company with servo-operated classical irrigation valves that works from 0.5 up to 10 bar (most manufacturers needs at least 1 bar). I think this should operate fine in my system. Now I have to choose amongst five different coils (see attached). I would like to order the 9V OS DC version so I would much appreciate if anyone can help me to choose the right coil that will best work with DC opensprinkler.

    Can 9vdc drive the 12vdc coils (number 1b and 2) with 705mA and 475mA, respectively? if the answer is yes that means I could use a 9v battery to power opensprinkler in case of power outage? After all, according to attached table, it seems that the 24vac coils (number 2) have better chances to operate normal with DC opensprinkler. Am I right?




    It looks like 2 (12VDC) and 3 (24VAC) should work fine with OpenSprinkler DC. 1b should also work fine, although it uses more power than 2. Yes, I believe that you can drive these with 9VDC (1amp) power supply that comes with OpenSprinkler DC. Generally these valves require a high inrush current to open, but once it’s open, the voltage required to stay on can vary over a wide range. So 9VDC to power 12VDC valves should be fine (and OpenSprinkler DC has internal booster to provide high inrush current needed).

    If you need to open two or more such valves at the same time (note: simultaneously), you may need to upgrade the power supply to 2amp or more to provide additional current capacity.



    Hi Ray,

    thanks. I am happy to hear that OpenSprinkler DC should drive both code 2 (12VDC) and 3 (24VAC) coils.

    Best Wishes

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OpenSprinkler Forums Hardware Questions Choosing the right coil