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-   -   New Vessel Sink without overflow drains slow (https://www.askmehelpdesk.com/showthread.php?t=39837)

  • Oct 30, 2006, 06:31 AM
    racroo
    New Vessel Sink without overflow drains slow
    I installed a new vessel sink without an overfolw and it drains very slow. When I loosen a connection and let some air in it drains fine, just like it did with the original undercounter sink. So I assume I need to do something to compensate for the lack of an overflow. Any suggestions? Thanks.
  • Oct 30, 2006, 07:55 AM
    iamgrowler
    Quote:

    Originally Posted by racroo
    I installed a new vessel sink without an overfolw and it drains very slow. When I loosen a connection and let some air in it drains fine, just like it did with the original undercounter sink. So I assume I need to do something to compensate for the lack of an overflow. Any suggestions?. Thanks.

    Is the sink just resting on a slab countertop with the connections underneath exposed?

    Or is this a vanity situation with doors and unexposed connections underneath?

    If it is a vanity, you can put in a sanitary tee laying on its back where the drain comes out of the wall and install an air admittance valve.
  • Oct 30, 2006, 08:28 AM
    racroo
    Quote:

    Originally Posted by racroo
    I installed a new vessel sink without an overfolw and it drains very slow. When I loosen a connection and let some air in it drains fine, just like it did with the original undercounter sink. So I assume I need to do something to compensate for the lack of an overflow. Any suggestions?. Thanks.

    Thanks. Most of the plumbing is hidden in a cabinet. What is an air admittance valve and where can a find a picture or sketch re. installing it? Is this a common problem with vessel sinks? Can I just buy one of those bottle drains like Deco sells instead?
  • Oct 30, 2006, 08:51 AM
    iamgrowler
    Quote:

    Originally Posted by racroo
    Thanks. Most of the plumbing is hidden in a cabinet. What is an air admittance valve and where can a find a picture or sketch re. installing it? Is this a common problem with vessel sinks? Can I just buy one of those bottle drains like Deco sells instead?

    Tom posted a really good picture of the set-up in another thread.

    As for the bottle trap, it isn't going to help you with this situation.
  • Oct 31, 2006, 04:04 AM
    racroo
    Learned that the problem is with a lack of air ahead of the P Trap. Does anyone know if codes will let me put the air admissions valve in front of the P trap?
  • Oct 31, 2006, 04:09 AM
    racroo
    New Vessel Sink drains slow
    I installed a new vessel sink without an overflow and it drains very slow. When I loosen a connection between the sink and P Trap and let some air in it drains fine, just like it did with the original undercounter sink that had an overflow. So I assume I need to do something to compensate for the lack of an overflow. Does anyone know if Codes will let me put an air admissions valve in front of the P trap? Thanks.
  • Oct 31, 2006, 05:55 AM
    speedball1
    65535 Attachment(s)
    You have installed a standard lavatory drain on your vessel sink and now you are air locked.
    You need a vessel sink drain,(see image) For $31.00 this can be remedied. Click on; http://www.nextag.com/vessel-sink-po...in/search-html
    To check it out.
    Good luck, Tom
  • Oct 31, 2006, 07:53 AM
    iamgrowler
    Quote:

    Originally Posted by racroo
    I installed a new vessel sink without an overflow and it drains very slow. When I loosen a connection between the sink and P Trap and let some air in it drains fine, just like it did with the original undercounter sink that had an overflow. So I assume I need to do something to compensate for the lack of an overflow. Does anyone know if Codes will let me put an air admissions valve in front of the P trap? Thanks.

    Putting the AAV in front of the trap will suction the trap dry.

    I still think your problem has to do with your vent.

    It is either plugged, non-existant or is blocked by the bend of the trap that goes into the wall.

    Some people make the mistake of pushing the bend all the way into the back of the fitting, which blocks the drain opening.

    As for compensating for the lack of an overflow, look at it this way, kitchen sinks, bar sinks, mop sinks and floor sinks all drain just fine without an overflow -- Your lavatory isn't any different.
  • Oct 31, 2006, 11:16 AM
    dclynch
    Tom - How does a vessel sink drain work? Thanks - Dennis
  • Oct 31, 2006, 12:07 PM
    speedball1
    Hey Dennis,

    In a regular lavatory the over flow acts as a vent. You do not have this in a vessel sink so a drain with a opening in the tailpiece that acts as a vent takes the overflows place.

    You said, "Learned that the problem is with a lack of air ahead of the P Trap."
    Entirely correct and a drain that's made especially for vessel sinks addresses that problem.
    This is not a venting problem. Your house vent relieves the suction caused by the discharge leaving the trap.
    A vessel sink generates suction BEFORE it gets to the trap and that's what slows down the action. Change out the drain and your problem disappears. Good luck, Tom
  • Nov 2, 2006, 03:21 AM
    racroo
    Quote:

    Originally Posted by speedball1
    Hey Dennis,

    In a regular lavatory the over flow acts as a vent. You do not have this in a vessel sink so a drain with a opening in the tailpiece that acts as a vent takes the overflows place.

    You said, "Learned that the problem is with a lack of air ahead of the P Trap."
    Entirely correct and a drain that's made especially for vessel sinks addresses that problem.
    This is not a venting problem. Your house vent relieves the suction caused by the discharge leaving the trap.
    A vessel sink generates suction BEFORE it gets to the trap and that's what slows down the action. Change out the drain and your problem disappears. Good luck, Tom

    Thanks. I boought a grid drain for vessle sinks and it made no difference. Interestingly, I stucj a straw down one of the grid holes and then all worked OK. It seems likse the individula grid drain holes were too small, I need to try the vent solution, or I simply need a wide open drain hole. Commnets??
  • Nov 2, 2006, 11:30 AM
    racroo
    Speedball: From the research I have done online I think the drain in the picture is for a sink with an overflow. In my vessel set-up the sink sets on a countertop and is connected to the tail piece under the counter, so there is nothing the vent holes shown in the picture are open to - i.e. they have to be below the vessel and are either facing the countertop or open to the air space under the cabinet, I which case a block could cause water to overflow into the cabinet. Does this make sense?
  • Nov 2, 2006, 05:25 PM
    iamgrowler
    Quote:

    Originally Posted by racroo
    Speedball: From the research I have done online I think the drain in the picture is for a sink with an overflow. In my vessel set-up the sink sets on a countertop and is connected to the tail peice under the counter, so there is nothing the vent holes shown in the picture are open to - i.e.,they have to be below the vessel and are either facing the countertop or open to the air space under the cabinet, i which case a block could cause water to overflow into the cabinet. Does this make sense?

    Can you post a picture of the drain set-up underneath the countertop?

    That would be very helpful.
  • Nov 3, 2006, 05:59 AM
    speedball1
    Here's another grid drain designed for lavatorys without overflows.

    http://www.homedepot.com/prel80/HDUS...p?pn=100088013
  • Nov 3, 2006, 06:08 AM
    racroo
    If you go to this website you will see the Kohler grid drain for vessel sinks does not have the vent openings.

    http://www.us.kohler.com/onlinecatal...0102&section=2
  • Nov 3, 2006, 06:16 AM
    racroo
    Yes the golden color grid drain is just like the one I have - it has no vents. Now you know what my set up looks like. I guess I am wondering if the vessel sinks which do not have overflow vents have an inherent design problem. This is why I am going to try using a vent in between the Ptrap and the sink - much like a vacumm breaker, unless someone else has any other ideas. As a follow-up - the straw I used to test the vacumn theory was inserted in one of the grid drain openings. As long as the straw was above the level of water entering the sink, the vessel drained normally. When water got above the top of the straw or when there was no straw the drain started to work slow. This is why Iam pretty sure that either the grid drain holes are too small, or the lack of a vent / air is the cause of the problem. Thanks again.
  • Nov 6, 2006, 04:25 AM
    racroo
    [QUOTE=notmyjob]hey racroo,
    I am having exactly the same problem as you with the slow draining of a vessel sink. Have you found a solution? I would appreciate any help you could pass on. -Carl[/QUO

    First, put a long straw into one of the grid drain holes (or into the drain if you have a different style drain). If you see the water drain faster, then you know that the lack of an overflow is causing the problem. I put an air vent (vacuum breaker) in front of the P Trap and that made a slight difference - only cost ~$10 for the vent plus a T fitting and elbow at Home Depot which I attached to the tail pipe inside my pedestal cabinet. I also filed the drain holes a bit to make them bigger, which helped too. What would certainly fix the problem would be to have an open drain with a stopper, but I decided that it now drains OK. You could also shut off the supply valves a bit to slow the water inflow. Let me know if any of this helps.
  • Nov 10, 2006, 08:22 PM
    Mr Ada
    I have a danze faucet with an overflow drain pipe. I want to be able to use the rod to actuate the stopper and didn't want to have to spend $80+ on each drain as I have 5 vessel sinks with danze faucets.

    What can I do to reengineer that opening made for the overflow? Is there a T pipe out there that can be mounted?

    Chris
  • Nov 20, 2006, 12:27 PM
    Toast
    I too have the same problem.
    Basin sink with no overflow drains really slowly (and passes the straw test).

    So far I've heard that yes, an Air Admittance Valve will work, and no it won't. Which is it?!

    Racroo - it sounds like your solution worked (and it sounds like a form of an Air Admittance Valve). But by "in front of" the P-trap, do you mean between the trap and the sink, or between the trap and the plumbing in my walls?

    Also, if a vacuum breaker or Air admittance Valve will work, how high does it have to be? I've heard 4 inches above the weir. But I'm not sure I have that clearance inside my cabinet, and I REALLY don't want to start busting holes in the walls to install this. (I can't install, even a nice looking breaker above the platform of the sink, as the basin sits on a granite top that I am just not cutting through.


    Any ideas from people who have actually solved this problem?
  • Nov 21, 2006, 04:37 PM
    racroo
    My sink now works great without the air valve (which was placed between the Trap and the sink drain tail pipe. What I did was replace the grid drain with a mushroom cap drain that has a much larger opening (three large openings to be specific). When you look at the total area of the three opending vs. the little grid drain holes it is MUCH bigger. I'm convinced if you really want the grid drain look another option would be to enlarge the holes, or try a different grid drain with larger or more holes. In any case, do not make the mistake of using a drain meant for a sink with an overflow as it will not work / could leak. If you decide to enlarge the holes, like I did as part of my first attempt at a fix, I found the air valce helped a bit, still not as good as the improvement when I swithced to the musahroom cap. Incidentally, both of the drains I used were by Decolav. Let me know if this helps.
  • Nov 22, 2006, 12:45 PM
    tinadev1
    Vessel Sink Drain Problem
    Hey y'all! We just purchased a lovely vessel sink WITH overflow, and a totally cool faucet. You already know what the problem is, most likely. Yep, slow draining! Here's the question: The faucet came with a simple "grid" drain, (no stopper) not a pop up. From all the questions and answers I've been reading about sinks, drains, etc. on here, I'm wondering if we should remove said drain, and install one of these pop-up's? When I'm washing my hands, when I get done and the water is slowly draining, if I run my fingers right across the grid a time or two, the water drains out quickly.

    The house is 136 years old, but the plumbing, thankfully, is at the most only 15. Following all your advice posted here, I've checked all the fittings and seals, made sure all visible pipes are clear, run hot-hot water until I drained the tank (and damn near melted the plumbers putty!), plunged gently... then forcefully, yada yada yada. The tub and toilet have no problems. The only thing I have not done is snake.

    Should I try the pop-up drain thing first? I would WAY rather do that than see what's up in the walls, and I don't CARE that it's only ten to fifteen years old! NOT something I want to know! EEEEEWWWWE! Thanks much... Tina :p
  • Nov 24, 2006, 12:25 AM
    speedball1
    The reason you have a drain problem that can be cured by running your finger
    Across the drains grid is the grid holes are so small they set up "surface tension". Click on, http://www.bathroom-glass-vanities.c...?source=nextag to find a pop up drain for vessel sinks that really drains. Regards, Tom
  • Dec 5, 2006, 06:30 AM
    Toast
    Quote:

    Originally Posted by racroo
    My sink now works great without the air valve.... What I did was replace the grid drain with a mushroom cap drain that has a much larger opening (three large openings to be specific).


    Awesome, this is what I was hoping to hear, not having to bother with an AAV.
    I'm planning on ordering a push-button or pop-up mushroom drain for the non-overflow basin. (That way I won't need a stopper when I do want to fill the basin.

    Thanks for your input... I feel better now hearing about someone's "proven" solution.



    Thanks,

    Toast
  • Dec 5, 2006, 07:37 AM
    speedball1
    Let me give you a link to a vessel sink umbrella type drain; http://www.bathroom-glass-vanities.c...?source=nextag
  • Dec 6, 2006, 08:13 AM
    JEANBETTISTEVENS
    Slow draining vessel sink
    What can be done to correct a very slow draining vessel sink?
  • Dec 6, 2006, 08:17 AM
    btuchman
    Quote:

    Originally Posted by tinadev1
    Hey y'all! We just purchased a lovely vessel sink WITH overflow, and a totally cool faucet. You already know what the problem is, most likely. Yep, slow draining! Here's the question: The faucet came with a simple "grid" drain, (no stopper) not a pop up. From all the questions and answers I've been reading about sinks, drains, etc. on here, I'm wondering if we should remove said drain, and install one of these pop-up's? When I'm washing my hands, when I get done and the water is slowly draining, if I run my fingers right across the grid a time or two, the water drains out quickly.

    The house is 136 years old, but the plumbing, thankfully, is at the most only 15. Following all your advice posted here, I've checked all the fittings and seals, made sure all visible pipes are clear, run hot-hot water until I drained the tank (and damn near melted the plumbers putty!), plunged gently... then forcefully, yada yada yada. The tub and toilet have no problems. The only thing I have not done is snake.

    Should I try the pop-up drain thing first? I would WAY rather do that than see what's up in the walls, and I don't CARE that it's only ten to fifteen years old! NOT something I wanna know! EEEEEWWWWE! Thanks much..... Tina :p

    We had a pop up that was slow. We had the plumber put in a flat screen. It is still slow. I am pissed.
  • Dec 6, 2006, 08:27 AM
    btuchman
    I have a Vessel sink with an overflow and it is slow. I don't think it is a vent problem. Is the drain pipe smaller?
  • Dec 6, 2006, 08:37 AM
    speedball1
    Quote:

    Originally Posted by btuchman
    I have a Vessel sink with an overflow and it is slow. I don't think it is a vent problem. Is the drain pipe smaller?

    Lavatory drain pipes have always been 1 1/4". Your vessel sink has a over flow built in the sink? What type of drain do you have? Did the lav you replaced drain good before you replaced it with a vessel sink?
    Your turn, Tom
  • Dec 6, 2006, 08:46 AM
    speedball1
    Please read the posts on this page. They deal with your problem and that's venting the drain on a vessel sink. More questions? I'm as close as a click. Tom
  • Dec 6, 2006, 08:23 PM
    btuchman
    What's deal? Did everyong just get Vessel sinks and they all stink?
    We just got one with a lift plug, it was slow, we changed it to a plain drain and it is still slow.
    What is wrong with them?
    Does anybody really know?
    Bruce
  • Dec 13, 2006, 09:40 AM
    Toast
    Quote:

    Originally Posted by racroo
    My sink now works great without the air valve (which was placed between the Trap and the sink drain tail pipe. What I did was replace the grid drain with a mushroom cap drain that has a much larger opening (three large openings to be specific). When you look at the total area of the three opending vs. the little grid drain holes it is MUCH bigger. I'm convinced if you really want the grid drain look another option would be to enlarge the holes, or try a different grid drain with larger or more holes. In any case, do not make the mistake of using a drain meant for a sink with an overflow as it will not work / could leak. If you decide to enlarge the holes, like I did as part of my first attempt at a fix, I found the air valce helped a bit, still not as good as the improvement when I swithced to the musahroom cap. Incidently, both of the drains I used were by Decolav. Let me know if this helps.



    UHG!!

    Well - I installed a Decolav pop-up mushroom drain. Didn't work at all. Everything is still slow. However I think that part of the problem is the trap piping. AFTER the P-TRAP, the pipe leading to the wall goes straight up almost to half the height as back up to the sink's drain. (And the P-TRAP is 1'5" lower than the sink drain). So my thoughts are that there is too much space to go back up after the trap, and without a lot of pressure the water will not drain right. (Though the old sink worked just fine, weird.)

    At this point, I already have a nice hole in the wall. So I plan on seeing how faw down I can rip out the PVC pipes (post P-TRAP), a then run a flex-tube pipe downward from the P-TRAP to the now shortened pipes behind the wall.


    Can someone confirm the following though:

    1) That if I decide to throw a AAV (Air Admittence Value) into the mix, whether I install it between the sing and the P-trap, or between the P-Trap and the pipes in the wall?? (I may shorten the pipes as I said above, AND install the AAV 9as the nuclear option).

    2) Are there any screw-on based parts from going from one pipe size to another? All my local hardware stores seem to have are non-screw-on tubes with rubber washers/seals (like one pipe having sex with another larger pipe and an o-ring to keep them air/water tight). Logically these non-screw ones 'should' work given there is normal pressure, but I think the backup in my pipe is causing them to leak. (Guess my mistake is going to Home Depot instead of Lowe's... huge difference in customer service).

    If that STILL don't work, screw-it, I'm removing the P-TRAP together and will try to find some sort of gravity/spring valve to let water down, and keep the air from coming up from the outbound pipes.



    Moral of the story: I think it's better to have a crappy old ugly sink that works, than a fancy new one that don't.
  • Dec 15, 2006, 10:55 AM
    speedball1
    Quote:

    Originally Posted by Toast
    UHG!!!!

    Well - I installed a Decolav pop-up mushroom drain. Didn't work at all. Everything is still slow. However I think that part of the problem is the trap piping. AFTER the P-TRAP, the pipe leading to the wall goes straight up almost to half the height as back up to the sink's drain. (And the P-TRAP is 1'5" lower than the sink drain). So my thoughts are that there is too much space to go back up after the trap, and without a lot of pressure the water will not drain right. (Though the old sink worked just fine, weird.)

    At this point, I already have a nice hole in the wall. So I plan on seeing how faw down I can rip out the PVC pipes (post P-TRAP), a then run a flex-tube pipe downward from the P-TRAP to the now shortened pipes behind the wall.


    Can someone confirm the following though:

    1) That if I decide to throw a AAV (Air Admittence Value) into the mix, whether I install it between the sing and the P-trap, or between the P-Trap and the pipes int he wall???? (I may shorten the pipes as I said above, AND install the AAV 9as the nuclear option).

    2) Are there any screw-on based parts from going from one pipe size to another? All my local hardware stores seem to have are non-screw-on tubes with rubber washers/seals (like one pipe having sex with another larger pipe and an o-ring to keep them air/water tight). Logically these non-screw ones 'should' work given there is normal pressure, but I think the backup in my pipe is causing them to leak. (Guess my mistake is going to Home Depot instead of Lowes... huge difference in customer service).

    If that STILL don't work, screw-it, I'm removing the P-TRAP together and will try to find some sort of gravity/spring valve to let water down, and keep the air from coming up from the outbound pipes.



    Moral of the story: I think it's better to have a crappy old ugly sink that works, than a fancy new one that don't.

    (1) you shouldn't have to add a AAV.
    (2) I take it you're looking for a 2 X 1 1/2" reducing coupling (see image) To check farther click on, http://secure.data-comm.com/RBIS/Detail.bok?no=79665
    (3) you're not going to find any. Spring loaded and mechanical traps are outlawed.
    Good luck, Tom
  • Jan 15, 2007, 07:00 PM
    afiore
    2 Attachment(s)
    Quote:

    Originally Posted by racroo
    I installed a new vessel sink without an overfolw and it drains very slow. When I loosen a connection and let some air in it drains fine, just like it did with the original undercounter sink. So I assume I need to do something to compensate for the lack of an overflow. Any suggestions?. Thanks.

    Here is the solution that my contractor came up with:
    Vent the drain by adding copper tubing out of the drain just below the vessel, through the wall, to a height exceeding the height of the vessel. (see attached photos)
    This solution provides a safe air admittance route to the drain pipe on the vessel side of the P-trap where it is usually provided for by sinks with overflows. The copper tubing will never overflow in the wall because it is higher than the height of the vessel. The vessel will always overflow first in the unlikely case of an undetected clog in the P-trap, the same risk that exists if there is no air admittance tube.
    If the homeowner is afraid to drill a hole in the wall, the air admittance tube can terminate as high as possible within the cabinet, or the tube can be run through a hole in the countertop behind the vessel.
    This solution allows the continued use of the attractive and unobtrusive grid drains in the vessel.
    With the air admittance tube connected the vessel drains very, very quickly.
    I think that this solves the only potential drawback to using these beautiful vessels.
    afiore
  • Jan 16, 2007, 08:24 AM
    speedball1
    Vessel draining problem
    afiore
    New Member Join Date: Dec 2006
    Posts: 1


    --------------------------------------------------------------------------------

    I am so happy with the solution I want to share it with you.

    Here is the solution that my contractor came up with:
    Vent the drain by adding copper tubing out of the drain just below the vessel, through the wall, to a height exceeding the height of the vessel. (see attached photos)
    This solution provides a safe air admittance route to the drain pipe on the vessel side of the P-trap where it is usually provided for by sinks with overflows. The copper tubing will never overflow in the wall because it is higher than the height of the vessel. The vessel will always overflow first in the unlikely case of an undetected clog in the P-trap, the same risk that exists if there is no air admittance tube.
    If the homeowner is afraid to drill a hole in the wall, the air admittance tube can terminate as high as possible within the cabinet, or the tube can be run through a hole in the countertop behind the vessel.
    This solution allows the continued use of the attractive and unobtrusive grid drains in the vessel.
    With the air admittance tube connected the vessel drains very, very quickly.
    I think that this solves the only potential drawback to using these beautiful vessels.
    afiore
  • Mar 13, 2007, 02:32 PM
    Marlow
    The problem with the copper pipe option is that if a clogged trap temps someone to reach for a plunger (a normal method in my books) the excess water will not push through the blockage but rather out the copper 'vent'. If this is in the wall you run the risk of pushing water into the wall cavity and causing all sorts of problems. The other problem is that it is hidden. It would be hard for someone to quickly asses what was done and why.

    In my opinion, an AAV between the sink and traps works best (I have has great success with it) and will cause no future problems. Also, if there ever is a problem, than any plumber/homeowner will be able to assess everything that is there. If aesthetics are a concern (one of the open design vessel sinks for example) run a small diameter pipe (1 1/4 brass drain for example) into the wall and towards the ceiling hooking it into either the main venting system or capping it with an AAV that can be accessed through a vent cover or something. I do wish they would make a better system but for now this has worked best for me.

    Cheers,

    Marlow
  • Mar 13, 2007, 05:13 PM
    btuchman
    I had that problem. Took out the pop up drain and still had the problem. Then I drilled bigger holes in the flat screen drain. That solved the slow draining, and have no worry or expense of extra plumbing. Just remember to smooth out the drilling burs.
  • Sep 18, 2007, 12:12 AM
    vector1701
    So was there a final solution to this problem? I am trying to determine if the new vessel sink I have just had installed, that of course has this issue, needs an AIR ADMITTANCE VALVE or should I drill the holes in the drain (would rather not do that).

    Thanks and I appreciate an update.

    Patrick
  • Nov 4, 2008, 11:04 AM
    yottaflops
    In an attempt to revive this thread, I'll post my thus-far futile attempts at solving the slow-drain problem with my darn vessel sink.

    When I first installed the sink, I had a grid drain. It drained very slowly, but once in a while, if I agitate the drain by rubbing my fingers across the holes in the drain, some air bubble comes up, and all the water drains almost instantly. From this I concluded that it shouldn't be a clog in the pipes.

    I was initially convinced that the problem is due to the lack of an air vent because of having no overflow, so I went to the Home Depot trying to find an AAV. They didn't seem to have one, and the plumbing guy there told me it had nothing to do with not having an overflow. He said it must be due to a clog, and suggested that I snake something through the pipes to clear the clog.

    I wasn't sure I believe him, but I tried plungers and drano, and it didn't help. I'm not convinced that it is a clog, because otherwise why would it drain so quickly once in a while when the air gets out?

    Then I also read this thread, about the problems with the grid drain, how it could be that the holes there are too small, and surface tension in the water is not permitting enough flow. I also read here, that kitchen sinks also don't have overflows, and they work just fine, and that makes sense to me. So, I replaced the grid drain with the pop-up, mushroom type drain.

    That didn't solve the problem either. But it was a tiny bit better: as long as I don't let water to rise to the level where it covers up the holes in the drain, it drains fine. As soon as the water rises above the level where the holes are completely covered, the flow slows dramatically.

    This leads me to believe that it is an air vent problem after all. What I don't understand is, the old question, why kitchen sinks work just fine without overflows? Is there something different there somehow?
  • Dec 4, 2008, 12:23 PM
    fifilynn
    I have a question pertaining to the subject of slow-draining vessel sinks without overflows.

    Below are 2 photos of the vessel sink and the drain plumbing. The sink drains VERY slow. The owner is not certain that the grid drain was made for a vessel sink without an overflow. He wants to add some sort of air gap/vent to a portion of the drain line to help the water drain faster.
    http://i288.photobucket.com/albums/l...photos12_2.jpg
    http://i288.photobucket.com/albums/l...mphotos1-1.jpg

    Any comments on whether a drain made specifically for this sink would help better than the air gap/vent?

    Thanks!
    :)
  • Feb 7, 2010, 08:07 AM
    ZebraMike
    Good posts by all, and thanks for all your preliminary investigation and solutions. I am an engineer that deals with piping systems regularly, and recently purchased a new house with a sink that has this same problem - so I came looking for ideas also.

    As stated by many, the problem is with the surface tension of the water acreoss the perforated plate, and the differential pressure above and below the plate. Inserting the straw illustrates this point. Additionally, you will notice that if you let the sink fill up to about the same height that the P-trap offers, it will all "flush" out and begin refilling... That is because the pressure above the plate has overcome the pressure below the plate. Therefore, the issue is not with the piping downstream of the trap.

    Some comments on your suggestions, and then I'll offer mine...

    An AAV is not the solution. You need to EXCLUDE pressure from the space between the sink and the P-trap, and an AAV lets air IN. The copper piping up the wall will work fine, but looks like a pain to install and does present a slight potential for hidden issues. Loosening the fitting below the sink sets you up for a potential water leak not seen into the cabinet below your sink. Drilling bigger holes in the perforated sink drain plate is not particularly aesthetically pleasing, and changing the drain out altogether is costly and a pain as well. And nobody can have a straw sticking out of their sink...

    What you need in this case is a devisce that WILL let air out, but WON'T let water out. It is called an air trap, and is commonly used in industrial piping systems to exclude air from the system. I looked on the internet, and found a small and cheap one made by Honeywell (model EA122A1002) for about $30. I installed a PVC tee in the vertical drain line between the sink and the trap, then a PVC 90, then a 1-1/2x1/2 PVC bushing, then a 1/2x1/8 brass bushing. The air trap is mounted in a vertical position, and has a 1/8" male NPT connection. Don't forget to rotate the housing on the air trap once it is installed, to allow it to operate properly.

    Works like a champ. I ordered the trap off the internet, and got the rest of the fittings at Lowe's (in one trip, no less!). Total installed cost was probably $40 or less for everything.

    Hope this helps. It's amazing to me that the vessel sink manufacturers don't offer an easy, effective, and safe solution to this very common problem. Just about any do-it-yourselfer can do this one - no plumber required...

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