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Slow flow toilet and AAV

Car_Mike's picture

Slow flow basement toilet with Air Admittance Valve on vent.  A few years back we finished the basement with a full bathroom and laundry room that all drain to an ejector pump. The laundry sink, washer drain, ejector pump and shower share a vent stack to a AAV.  The bath sink and toilet share a vent stack to a AAV.  A few weeks ago I noticed a sewer smell in the basement and then discovered that the cover on the holding tank was loose.  Upon tightening the cover, the toilet then began draining slowly.  I was certain that there may be blockage in the vent stack or the AAV had failed.  I removed the AAV from the vent stack and snaked the vent pipe all the way into the holding tank.  As a test, I flushed the toilet and all was good.  I then replaced the AAV to the vent stack and again the toilet drained slowly.  So I then concluded that the AAV had failed.  I replaced the AAV with a new Studor AAV; same result of slow draining toilet.  So in summary, with the AAV the toilet drains slowly; remove the AAV from that vent stack and the toilet flushes as you would expect.

Pictures attached showing rough plumbing drain and respective vent stack.

There are 3 other vent stacks in the plumbing system throughout the house that vent directly to the roof; however none are connected to the basement.

The AAV doesn't let air OUT, (post #211074, reply #1 of 1)

The AAV doesn't let air OUT, only IN.  It sounds to me like your problem is simply that the drain is clogged, so pressure builds up when you flush.

(And using an AAV in this scenario is a poor idea and would not be permitted in our jurisdiction, but that likely has nothing to do with your problem.)


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville