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  1. #1
    Join Date
    Oct 2007
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    3

    Default Air valve on water faucet

    Faucets on water lines leading outdoors have air valves/vents. When are these air valves to be opened? What prevents water to escape? What's the purpose of the vents?

  2. #2
    Join Date
    Aug 2007
    Posts
    6,481

    Default Re: Air valve on water faucet

    You're probably referring to "backflow" preventers. Basically, it's a spring loaded rubber washer that only allows water to flow in one direction - out of the faucet. Water pressure closes the valve and water flows out. When the faucet is turned off, spring tension pushes the washer to the open position and excess water pressure is relieved, preventing a siphon from occurring that could maybe draw non-potable water back into the house system.

    IMHO, this is not a bad idea, however the practice of which could be carried out in a fashion that didn't provide the user with a shower when the faucet is turned off. It is this shower that prompts many homeowners to remove the backflow device in the first place.

  3. #3
    Join Date
    Oct 2007
    Posts
    3

    Default Re: Air valve on water faucet

    [QUOTE=A. Spruce;5908]You're probably referring to "backflow" preventers. Basically, it's a spring loaded rubber washer that only allows water to flow in one direction - out of the faucet. Water pressure closes the valve and water flows out. When the faucet is turned off, spring tension pushes the washer to the open position and excess water pressure is relieved, preventing a siphon from occurring that could maybe draw non-potable water back into the house system.

    No, this is not what I'm referring to. I have these too and they're a good idea in preventing insecticides from back flushing into my water supply.

  4. #4
    Join Date
    Oct 2007
    Posts
    3

    Default Re: Air valve on water faucet

    Quote Originally Posted by DwarfWytch View Post
    The bleeder valve is opened (the third step)after you: (step one)shut off the inside supply valve, and after (step two) the outside valve is opened; in order to drain the line through the wall and outside for the winter/freeze danger periods you have to open this "air vent" or "bleeder valve", otherwise the water remains in that part of the water line after the inside shutoff valve,
    This sounds like the answer. The vent valve is a short 1/4" by 3/8" brass fitting on the faucet/hose bib. I guess I've been lucky over the years because I've never messed with it and I've never had pipe problems. Now to look for some wood to knock on...

    Thanks for the answers folks.

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