My girlfriend bought a below the counter Kohler sink - I believe they
call them a vessel sink, which has no overflow on it. The issue is
slow drainage associated with it. It does have venting, proper P trap,
Reading the newsgroups - apparently this is a common issue (I read)
because the lack of the overflow (which also acts as a vent)
essentially creates a 'vacuum'. Sort of like trying to pour water
quickly out of an inverted pop bottle.
Ok - so this made sense to me and what I saw was some suggested a
'cheater valve' between the sink and the P trap. others said that a
mushroom valve(?), others said make bigger holes in the grill to
relieve surface tension if you have that type of drain, others went so
far as to run copper piping instead of a cheater valve out behind the
wall above water level !!(sheesh)
To me, it seems they sell a zillion of these things and they would not
if there was some inherent major issue with them, so there must be
something I am missing. I dropped into my local electrical and
plumbing place to see what they had to say.
They said they sell tons of them, with no complaints about drainage,
but they always sell them with a push type pop up drain, as opposed to
the pull a lever and it raises and lowers the drain to open and close
Ok - fair enough, but if the issue is indeed one of a vacuum, how does
using a mushroom (I think they are called) popup solve the problem? Is
it simply that the design on the push on, pull off with a lever system
blocks too much of the drain without a vent to drain quickly? Or is
there something else that needs to be done that they are forgetting to
In other words - how the heck do I fix this thing so it will drain
properly and I can gain major brownie points in the process? ;^)
Before you spend any money, verify that the vent pipe works. Go up on
the roof and run a garden hose down the vent stack. You can even turn
on the water if you believe that it's clear.
One symptom of a clogged (or badly designed or nonexistent) vent stack
is "glugging" when you empty the sink. The water, when it finally gets
going, sucks all the water out of the trap just after the sink finishes
emptying, making a "glug, glug" noise and leaving the trap empty. This
doesn't *always* occur, but if it does, it's a dead giveaway.
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