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Thread: Solenoid problem

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    Default Solenoid problem

    I have installed 12volt solenoid valves in my house plumbing (new home) to return cold water from the hot taps. Trouble is they open fully instantly, which isn't a problem but when switched off they close instantly as well causing water hammer. Is there some way of making them close slower? I tried a capacitor but it didnt seem like it made any difference. Am I on the right track or what?



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    LSemmens
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    Solenoids are mechanical, they are either on, or off. You may need to install expansion tanks, too.
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    Yes its mechanical in a sense but operated by an electromagnet. If the voltage could be ramped down instead of cut off will it close slower?

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    All solenoids have a operating voltage .If the voltage could be ramped down instead of cut off will it close slower? the answer is no !! the hammering is caused by the sudden stop of water flow ,So when you reduce the voltage you will get to a point where the solenoid shuts and it hammers , a tap doesn't hammer as it closes slowly reducing the water flow until its off , so you need motor driven taps
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    The valve is the mechanical part. As hinekadon has explained the solenoid bit (the cylinder where the wires go in) is either on, or off. If you pull one apart all you will find is a needle and seat. once the needle hits that seat, the water flow stops because of the pressure differential on the diaphragm.
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    Think you need one of these :

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    Oh well here goes to stop water hammer you need to absorb the water pressure at the point that its generated ie at the solenoid , as you cant compress water ! you have to change it to a medium that can be compressed , hey presto air is easily compressed so if we put a large enough air tank tee,d into the hammer-side of the solenoid it will absorb the shutoff shock and dissapate the hammer into the traped air as they do on pumps to get them started , understand ??????>? say if you dont
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    Ok thanks guys I realise now that nothing can change the way they operate. If the electromagnet loses force the water pressure takes over and slams the valve shut, hence the inertia of the water column causes water hammer. I could use air filled arrestors but I would need 5 of them. I will try closing down a valve on the downstream side to slow the flow.

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    It would be a nice gesture to click on the little thanks button to thank posters , dont you think ?????? try it , then your numbers will show an improvement . You run the risk of not getting a reply if you dont have any numbers here regards don
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    depends on your house construction , but sometimes if the hammer is caused by a loose pipe ( maybe a long straight run ) and you can locate the loose pipe , try injecting some of that expanding foam filler into the surrounding cavity , which will restrain the pipe a bit.

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