Trap primer needed on unused floor drain?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by karsc01, Jul 31, 2006.

  1. karsc01

    karsc01 New Member

    Here's a simple question. I'm planning on installing at least one (probably two) floor drains. It is a dry basement and they will only be there in case the water heater or the washing machine spring a leak. So most likely they will never be used.
    Now I could install a trap primer to make sure the trap under these drains always has water in it. However I was wondering.. would it be possible to just poor antifreeze or oil down these drains to fill the trap similar to when you winterize a house? Then I wouldn't need to bother with a trap primer. Is this a terrible idea for any reason I'm missing? Would it smell or something? I don't recall our house ever smelling after coming back from having it winterized all season long so I don't think it would be a problem but I've never heard of someone doing this (though it seems obvious).
    Thanks for your thoughts...
    Last edited: Jul 31, 2006
  2. Terry

    Terry Administrator Staff Member

    Bothell, Washington
    As far as I know, inspectors still want trap primers.

    The fact that the drains aren't used, is just more reason to have the primers.


    This trap primer keeps both the trap above primed, for the condensate pumps of both the furnace and the refrigerator in the next room, but also the floor drain.
    The floor drain line is in blue going into the slab.
    Last edited: Mar 4, 2014
  3. Gary Swart

    Gary Swart In the Trades

    Yakima WA
    When you winterize traps, never use oil of any kind. RV antifreeze is OK, but do not use automobile antifreeze.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    I have used anitfreeze when the drain does not have an existing trap primer and there is no way to install one. You just have to remember to replenish it if you dump water on the floor.
  5. Recurring dilemma. How to keep floor drains functioning properly.

    The question is the same one I faced when I decided to add floor drains in my two bathrooms.

    This is a recurring question. Does anyone have a solution?

  6. GregO

    GregO Member


    You may want to check out

    Anybody else out there ever use this or similar type of product?

  7. Spaceman Spiff

    Spaceman Spiff Architect

    Salt Lake City, Utah
    We have these installed on every commercial job we design. We have stopped using trap primers all together. Primers were always clogging up and there was a call back to replace the primer. No call backs in past 4 years and numerous buildings... (Plumbers are sceptical at first but now think we're geniuses. We just stumbled onto them...)
  8. With a P-trap, could work.

    i looked into this option back in the days when their promotional material said they could REPLACE a P trap. I rejected that option. Some smell still does come back out, is what I heard from several Master Plumbers and other sources.

    This thingie looks like it could slow down the rate of evaporation (of the water in the P trap) by a lot.

    In conjunction with a P trap, it is a good idea. The P trap would still need to be refilled occasionally.

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