(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 7 of 7

Thread: Air chamber--drop elbow vs drop tee?

  1. #1
    DIY Junior Member Neptune's Avatar
    Join Date
    Oct 2012
    Location
    Illinois
    Posts
    5

    Default Air chamber--drop elbow vs drop tee?

    Why does it seem customary to install an air chamber as a water hammer arrestor using a brass drop elbow with a tee fitting beneath it to branch off to a separate arm, like a saquaro cactus? Wouldn't it be easier just to use a brass drop tee and extend the piping up to form the air chamber? When the stub out the wall is just a copper pipe, it seems common to do this with just a sweat fitted tee.

    I'm aware of the debate as to whether air chambers are useless, anyhow, but I intend to install one for the feed to a new toilet, just in case. I want to make sure I'm not overlooking something on how this should be done.
    Last edited by Neptune; 11-03-2012 at 08:10 AM.

  2. #2
    DIYer, not in the trades LLigetfa's Avatar
    Join Date
    Feb 2011
    Location
    NW Ontario, Canada
    Posts
    3,680

    Default

    Are you talking about a low-tech hammer stop that is just open-ended? Those will waterlog over time as the air gets absorbed. They should be mounted on the top of a Tee so as to collect any air that may be in the water stream.

    The better hammer stops have a piston with a pre-charged, closed air reservoir that are not prone to waterlogging so the air supply need not be replenished by accumulating air. They can and should be installed as you say, with an elbow so as to not accumulate air, thereby keeping the O-ring seal on the piston lubricated.

  3. #3
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,638

    Default

    Three things;
    1. You already know that air chambers are only effect for a short time, until the water absorbs the air.
    2. It is almost impossible to recharge an air chamber, regardless of what anyone tell you about turning off the water and draining the pipes.
    3. A toilet is the one fixture that seldom, if ever, needs an air chamber.
    Licensed residential and commercial plumber

  4. #4
    DIYer, not in the trades LLigetfa's Avatar
    Join Date
    Feb 2011
    Location
    NW Ontario, Canada
    Posts
    3,680

    Default

    Quote Originally Posted by hj View Post
    Three things;
    1. Assumes low tech, not pre-charged piston type.
    2. May depend on how and where they are installed.
    3. Very true.

  5. #5
    DIY Junior Member Neptune's Avatar
    Join Date
    Oct 2012
    Location
    Illinois
    Posts
    5

    Default

    Thanks for your observations.

    I agree that an arrestor of any sort is probably not necessary, but I happen to have on hand a drop ear tee but not a drop ear elbow. So, I'm thinking--why not just use that and add another 14" of pipe with a cap, just to cover old school practice?

    This, then, led me to wonder why you see the "cactus arm" configuration so often, which takes extra fittings and joints, and not nearly as elegant as using a tee.

    Maybe the answer has nothing to do with flow characteristics or the like, but simply that plumbers typically have in their trucks a supply of drop elbows but not drop tees!

  6. #6
    Forum Admin, Expert Plumber Terry's Avatar
    Join Date
    Aug 2004
    Location
    Bothell, Washington
    Posts
    14,201
    Blog Entries
    1

    Default

    It's been a long, long time since I've installed an "air chamber"

    In the plumbing code; if there are installed, there must be a way of draining them down.
    What is approved is hammer arrestors. In a tight (closed) system, those would be installed on quick closing valves.
    Ice Maker
    Dish Washer
    Clothes Washer

    All of these have solenoids.

    And yes, a hammer arrestor can fail too.

  7. #7
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,638

    Default

    quote; 1. Assumes low tech, not pre-charged piston type.
    2. May depend on how and where they are installed

    1. Mechanical styles are "shock absorbers" NOT air chambers
    2. A filled air chamber is like a straw with your finger over the end of it. The liquid will NEVER drain out until air can get into it, and there is NEVER enough "pressure" to force air in, AND even if there were few systems are installed so that ALL the water can be drained.

    As far as the location, good hydraulics specifies that the inlet to the shock absorber be in line with the direction of water flow.
    Licensed residential and commercial plumber

Similar Threads

  1. How deep is your Drop Ear Elbow ?
    By Telemarkjim in forum Shower & bathtub Forum & Blog
    Replies: 8
    Last Post: 02-04-2011, 06:27 PM
  2. Shower Arm & Drop Ear Elbow
    By bricksnsticks in forum Shower & bathtub Forum & Blog
    Replies: 4
    Last Post: 11-14-2009, 04:11 PM
  3. Securing 1/2" drop elbow
    By BimmerRacer in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 7
    Last Post: 08-21-2009, 01:15 PM
  4. Drop Elbow for shower bar rough in
    By Xenomorph in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 4
    Last Post: 11-10-2006, 04:30 PM
  5. Stripped drop elbow HELP
    By daves in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 6
    Last Post: 06-28-2006, 08:38 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •