Basement Sump Pump Siphoning & Air-locking

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by jasonw83, May 28, 2010.

  1. jasonw83

    jasonw83 New Member

    May 28, 2010
    Alberta, Canada
    I have a basement sump pump which operates as it is suppose to. The pump operates till the water level drops and the float switch kicks the pump off. But at this point the outgoing water effectively siphons the remaining water out of the sump causing the pump to become air-locked. After becoming air-locked, once the sump has filled the pump will run continually for days without pumping any water.

    I'd like to know if there is a anti-siphon valve I can put in this system to stop this from happening. Alternately I've also been thinking about drilling a hole in the discharge line above the pump but before the check valve.....Just wondering if this is allowed by code.

    Any suggestions would be greatly appreciated.

  2. cacher_chick

    cacher_chick Test, Don't Guess!

    Jan 5, 2008
    Test, Don't Guess!
    Land of Cheese
    The pumps I have dealt with (Zoeller) included instructions to put a small hole in the discharge pipe in the crock between the pump and check valve.
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  4. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Jun 22, 2009
    Red Seal Journeyman Plumber & Licensed Gas Fitter
    Penticton, BC
    I doubt code would have anything to say at all about drilling a hole in the discharge of the pump. It's done all the time......

    You could also try leaving more water in the sump when you pump it out.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    There is NO WAY to leave more water in the pit if it is being siphoned out. IT will siphon until ALL the water is gone and the system sucks water or the water level in the pit drops to the elevation of the pipe's outlet. A hole in the pipe will allow the air trap to be evacuated as water fills the pit. If the pump is running without pumping water, your shaft seal is probably damaged and you will need a new pump shortly.
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