drum trap or not?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by rick.a, Apr 25, 2007.

  1. rick.a

    rick.a New Member

    Jan 11, 2007
    Palmer, Massachusetts
    As part of a total kitchen remodel I need to reinstall a kitchen sink drain. The existing 1 1/2 pvc goes straight down thru the floor to the crawlspace. The prior setup had a drum trap. I was told that this was because of the long drop from the sink. Should I put in another drum ( I have heard negative references to them) or use a P-trap? If I use a P-trap followed by an ell to go straight down it will then be an S which is not good. Is this correct? So what should I do?

    The vent is also a problem since I cannot go up. I want to use an AAV to solve this.
  2. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    Last edited: Apr 26, 2007
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  4. Peanut9199

    Peanut9199 Customer Service Manager Plumbing Wholesale

    Apr 23, 2007
    Customer Service Manager Plumbing Wholesale
    Ontario, Canada
    A p/trap with an elbow is fine (s/trap) drum traps are good to catch straws or popsicle sticks that fall down a kitchen sink, but a union p/trap works just as well.
  5. markts30

    markts30 Commercial Plumber

    Sep 25, 2006
    Commercial Plumber
    Phoenix, AZ
    I would have to disagree and go with what Terry said...
    PTrap into a santee with a "studor vent" style AAV above it...
    STraps are illegal/not code compliant and tend to cause problems....
  6. dubldare

    dubldare Plumber/Gasfitter

    Sep 14, 2005
    Being this is a "total kitchen remodel", why can't the budget be found to bring your plumbing up to standards that have been around for over 125 years?

    Why can you not go up? Six inches above the flood rim of the fixture allows you to route horizontally to where you can go up. 45 degree offsets are considered vertical runs below the tops of fixtures. Relocating the waste line going through the floor and 'dirty' arming back toward your fixture's trap is a good way to clear windows that may be above the sink. Another option is an island vent, yet this still requires an accessible vent, which may be in an interior wall.

    I usually look at it as this, if it is structurally impossible to provide venting for a fixture at a given location, consider an island vent or a different location. If there's a bit of wallboard in the way, it can be patched. If it's too much work to do it correctly, consider not having the fixture alltogether.
    Last edited: Apr 25, 2007
  7. Master Plumber Mark

    Master Plumber Mark Master Plumber

    Feb 6, 2005
    Sensitivity trainer.. plumber of mens souls
    indianapolis indiana - land of the free, home of
    Dubldare.... overkilling a project....

    Their is doing things the right way and then their is makeing a mountain out of a mole hill.

    this is not the space shuttle or a hospital, its a kitchen sink drain.---in a kitchen

    So why in the world would you want to find a way to make an island vent for something that would work fine for the next 50 years with a Auto air vent and p trap????

    They make those Auto Air vents and have been useing them for at least 25 years.....they are legal almost everywhere...because they work great.....

    so why would you want to beat your braines out trying to
    tear up a wall and install an isalnd vent and do something
    that way...

    especially when that drum trap did an ok job

    for 100 years already??
  8. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    One problem is that most places do not allow the sink trap to be under the floor, except maybe Wisconsin.
  9. dubldare

    dubldare Plumber/Gasfitter

    Sep 14, 2005
    Mark, with all due respect, I'm going to re-iterate my stance.

    Since when is correctly venting a fixture during a "total kitchen remodel" making a mountain out of a mole hill? Since when are non-vented fixtures the "right way"? Since when is the "let sleeping dogs lie" mentality ok because it's too much like work to do it right; or to even let the asker consider what is approved from a code perspective v/s 'what you got has worked'.

    Does not matter from a code perspective. Fixture is a fixture no matter where it is.

    The island vent is listed by me as a code approved alternative to conventional venting methods. This brings me into your next statement:

    You imply that something that's been around for at least 25 years is going to become something that will last 50 years. AAV's have been used for over 25 years in trailer houses, per the very relaxed HUD and DOT codes which govern such dwellings.

    Now I don't beat my drum, but I too am a master plumber in both Minnesota and North Dakota. Minnesota has a proprietary plumbing code which predates the UPC (1933), and North Dakota has an amended 2000 UPC. Neither code allows for AAV's.
    Minnesota will allow an island vent (boston loop or as seen here: https://terrylove.com/images/island_vent.gif ) if structural limitations prevent conventional venting methods. North Dakota will allow the boston loop, or the more common method of increasing the fixture branch sizing twice to 3", and venting the 3" within 15' of the fixture.

    Because I know better.

    One thing that the AAV does not account for is backpressure. The AAV can only prevent backsiphonage, it cannot relieve the drain of any positive pressure that may exist due to upsteam fixtures discharging, downstream blockages or foaming from nearby suds producing fixtures. Additionally, up north where it gets cold, we are required to ventilate the city's sanitary sewer system through our DWV systems. Come on up here next time it's cold, I'll take you on a roof of any vacant building you choose. We can bask in the warm air that's coming up through the VTR's. :D

    Perhaps the biggest issue as to why I find myself typing this, (rather than doing stuff that I might get benefit from) is we, as professional plumbers, have an obligation to provide information that is codeworthy. Now, some may say that's overkill, but codes are nothing more than minimum standards. Doing something to code is not overkill, it is the bare minimum of what is needed to be found sufficient. We do have an obligation not only to our craft, but to the end user, to ensure that they have a system that is safe and requires minimal maintainance.

    I, as a professional, shouldn't be in the buisness of circumventing minimum standards and neither should the rest. I treat my responses as if someone were paying me +$100/hr to do their work. I treat myself as a resource of information. If that information goes against the grain somestimes, so it goes. I don't find myself at the doctor asking for only the good news or what I want to hear.

    Sorry for the schpiel, had to get that out.
  10. geniescience

    geniescience Homeowner

    Nov 27, 2005
    humid summers hot, humid winters cold
    wow. Can i quote this?

    I'll try to make a little summary for the original thread question, and include some background information.

    A long distance drop down to a P trap can lead to the P trap being sucked open by the water's own inertia, so it is not recommended.

    An S trap, even on a low-flow drain like a little sink, has a permanent problem since it relies on the rest of the plumbing system to compensate for its lack of venting. There is never any guarantee what is, or is not, happening in the rest of the house.

    A drum trap has so many problems that it is not acceptable anywhere, AFAIK.

    The only bulletproof option is a P trap, and a vent, near the sink.

    A few ways to do that (vented P trap) have been described; the easiest way (with an AAV) is far from being bulletproof, for the reasons described eloquently in the previous post.

  11. Dunbar Plumbing

    Dunbar Plumbing Master Plumber

    Apr 18, 2005
    Service Plumber, Outdoor Temperature Relief Owner
    Northern Kentucky/Greater Cincinnati Area
    To add to dubldare's statement I know without any doubt that KY has some of the strictest codes in regards to plumbing. So when I hear about AAV's and wet vents, loop vents or any other SHORTCUT that is allowed by one state and NEVER by KY's standards....I look at the necessity and function theory behind the logic.

    I got a friend in Michigan that they allow AAV's for everything. You'll see a new addition wiht small vent covers throughout the home with them being used as access to those AAV's.

    Now folks, the majority of homeowners don't fix their plumbing until it fails. Remember that AAV's are a mechanical device: it will fail. Either the diaphragm ripples and loses it seal or the spring weakens/tempers/breaks just like in a backflow assembly from repeated use.

    AAV's are a shortcut. They'll fail and the non-knowing homeowner will then be subjected to sewer gases which can cause health problems, create bacteria enriched atmosphere.

    I really wish all states followed the strict standards that KY and NY follow. Such a better design and creates a better operating system with less failure. I've heard of 2" or 1.5" stacks going through the roofs, no cleanouts at the base of stacks, no isolation valves on toilets and kitchen sink faucets or lav's ....??!?

    I personally like my state having a difficult code.
  12. Master Plumber Mark

    Master Plumber Mark Master Plumber

    Feb 6, 2005
    Sensitivity trainer.. plumber of mens souls
    indianapolis indiana - land of the free, home of
    Codes are diffferent everywhere

    I completely understand what you are talking about..

    dont take me personally......

    codes are different everywhere.....so be it....

    Indiana is pretty rlaxed when it comes to plumbing
    compaired to all around us...that is true.true ..true...

    I really ought to post some of the things I have seen that
    is considered code here......

    so you can all GAWK and laugh at
    the new home plumbing
    that is considered ok here....

    I have seen stuff done in new homes that actually
    made me stop in my tracks and stare for a while...

    here in Indiana you can run a kitchen with no vent ,
    only a aav under the sink, we can run a 3 inch drain to the kitchen
    and then reduce it to 2 inch and simply put a 2 inch elbow tothe trap...

    the downside to all this is just about anyone can do plumbing here
    and get away with it......

    a difficult code keeps real plumbers in business and
    makes plumbing more of a trade or a guild. that it used to be.....

    but it has to be enforced all the way into the hardware stores....


    you got to do what is code in your state..
    and ..I completely understand....

    but I would venture to bet you that if you were to go to

    LOWES in your home town...
    you will find the Auto Air Vents...and the average
    do it your selfer will install it before going to the troubles
    that the plumber would ....

    so their is a fine line between code and economics and

    landing the job ......

    if you tell someone you have to do this and that to meet
    code for $350 more

    and they see a 2 dollar auto air vent at LOWES
    that they can install themselves......with a can of glue , a hack saw
    and a little advice from the dummie at LOWES...

    what do think the odds are he might do it himself
    and tell you to take a hike....???
    Last edited: Apr 28, 2007
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