Air Chambers

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Oliver, Oct 13, 2005.

  1. Oliver

    Oliver New Member

    Messages:
    35
    Are they any specific requirements in terms of locations for air chambers in the UPC? In a simple one family home where should they be - washing machines (cloths and dishes), WC? Where else? Are they a must.
  2. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

    Messages:
    1,328
    Location:
    Columbus, OH
    I think Air chambers are a no no these days. They can get all mucked up if they don't fill up over time leading to stale air and bacteria getting into your potable water. Check out this article.

    http://www.builderswebsource.com/techbriefs/waterhammer.htm

    Discussion on air chambers, causes of water hammer and squeal and hammer arrestors.

    Jason
  3. Vitaliy

    Vitaliy New Member

    Messages:
    73
    Location:
    Massachusetts
  4. finnegan

    finnegan New Member

    Messages:
    250
    Location:
    CT
    I have read recommendations against air chambers as well. Same reason - stagnant water and bacteria. The mechanical water hammer arestors are supposed to work well, but you have to place them in accessable locations. Installing your pipes carefully can help reduce water hammer.
  5. casman

    casman New Member

    Messages:
    78
    Location:
    New York
    Well now I'm thinking I should replace all the air chambers in my home, is this really as bad as it sounds, are there any links to these studies, besides someone making claims about bacteria etc....Also I have a run of pipes that used to go to an upstairs kitchen. These were removed back to the shutoff valves. So there is about 6 feet or so of dead end pipes. Should these be removed as well?
  6. Terry Love

    Terry Love Plumber

    Messages:
    37
    Location:
    Bothell, WA
    The main reason air chambers are a no-no, is that they water log.
    If you have them in the system already, I wouldn't worry about them.

    Any hardware or plumbing store should carry hammer arrestors.
    I find them where they sell the copper fittings.

    If you have a closed system, (check valves, PRV's) then hammer arrestors are required at all quick closing valves.
    These would be
    Dishwasher
    Icemaker
    Washer

    If you're wondering about stars (***) in posts, I do block some web sites.
    If you've never seen the back end stats on a board like this, you would be amazed at the number of attempts to take over and shift it into a full blown advertising medium. Sometimes 10,000 attempts per day.
    Last edited by a moderator: Oct 14, 2005
  7. Oliver

    Oliver New Member

    Messages:
    35
    Quote: If you have a closed system, (check valves, PRV's) then hammer arrestors are required at all quick closing valves"

    Forgive my ignorance, what is closed system and the acronim PRV?

    Since the arrestors have to be accesible what would be the most suitable location for them in an One story house (in the basement/crawl space)?
  8. Terry

    Terry Administrator Staff Member

    Messages:
    15,112
    Location:
    Bothell, Washington
    A close system is a water supply system with either a check valve on it, or a pressure reducing valve.
    Without these, the water can expand as much as it likes and in the process, pressure builds.

    Quick closing valves are generally solenoid operated.
    They are required on ALL quick closing valves.
    Washer, dishwasher, icemaker.

    Tub and shower valves are not considered quick closing.

    An approved hammer arrestor may be hidden in walls.
    We do this all the time.

    It's air chambers that need accessible drains.
  9. Oliver

    Oliver New Member

    Messages:
    35
    Thanks

    And I assume that both hot and cold supplie pipes need arresters.
  10. kordts

    kordts In the Trades

    Messages:
    551
    Location:
    exurban Chicago
    I have found that not running any 1/2" pipe in a house will eliminate the need for air chambers. When I do work that is going to be inspected, I install them. Otherwise, the minimum pipe size I run is 3/4", with 1/2" only as risers to fixtures. Water hammer is a function of velocity. Smaller diameter=higher velocity. Larger diameter=slower velocity.


    Peace out,

    Kordts
  11. Oliver

    Oliver New Member

    Messages:
    35
    That was my approach - running 3/4" pipe and only the risers being 1/2". But I am subject of inspection.
  12. Terry

    Terry Administrator Staff Member

    Messages:
    15,112
    Location:
    Bothell, Washington
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