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, etc.installed.
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 it.
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 tell me?
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? ;^)
TIA