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Thread: put in my own basement sink, forgot a vent for the washer ptrap

  1. #1
    DIY Junior Member majorwoo's Avatar
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    Default put in my own basement sink, forgot a vent for the washer ptrap

    Ok, history
    The previous homeowner had done a wonderful job of discharging the washer into a 2" pvc pipe about 7" overhead. It was literally 3 washer discharge lines connected end to end going to a 2" pipe with a single upturned 90" elbow and the discharge line stuck in that. There was a rag stuck in it to "seal" the smell. For some reason I can not quite explain this didn't leak all over(I guess the washer was just discharging straight into the line that led out and there was nothing slowing it). It did manage to smell though when you washed anything.

    The Plan
    I knew this wasn't right, so I set about doing some research to make it right by putting a sink in the basement(the wife wanted one), and a pump (http://www.waterace.com/sump_6.html from Lowes) to pump the water from the sink/washer up and out. I had never worked with a dry vent before but I thought I understood the concept, so I ended up with the following:

    Pictures
    http://www.woosworld.net/images/base...ntwdsink01.jpg
    http://www.woosworld.net/images/base...ntwdsink02.jpg
    http://www.woosworld.net/images/base...ntwdsink03.jpg

    Quick Picture Explanation
    Picture 1: Obviously the washer stack, washer p trap (and hot/cold supply lines). I used a P trap with a clean out because I thought I was being smart.
    Picture 2: The horizontal line on the left is the input to the pump from the sink/washer. The Front left vertical line is the discharge (notice the checkvalve) that runs up inside the drop ceiling and 90's over to the 2" drain line out to the septic tank(I know know why there is 2 lines into my septic tank). The rear right vertical line is the vent line that runs up inside the drop ceiling where it is capped with a studor AAV (As i don't have existing dry vent's anywhere in the house to tie into). All 3 lines have a flexible coupling in case I need to pull the pump back out. You can see the horizontal line running from the washer stack behind the 2 vertical lines over to the tie into the pump input.
    Picture 3: You can just see part of the wye behind the sink leg there. The wye simply goes up into a 90 elbow and you can see it in picture 2 running behind the pump lines over to the washer stack.

    Things I've figured out I did wrong
    #1) I've put my wye in backwards, so it's directing the water being discharged from the washer towards the sink and not towards the pump (I'm not sure how big of a problem this is, but easily fixed if needed)
    #2) I've not vented my washer P trap. I guess I thought that the vent from the pump was going to cover me but that does not seem to be the case.
    #3) I used the existing washer discharge line - this flimsy thing kinked on me and the washer blew 1/2 it's load onto the floor. This is easily fixed with a new hose.
    #4) It would have been smarter to put the flexible coupling I intended for easy removal of the pump before the check valve. As it stands now if I open the coupling any water above is going to come back down :/

    Real Problem
    Problem is the sink fills up rapidly, and the pump kicked briefly and then stopped. The sink was filled to the brim with water. After waiting a bit for the pump to kick in I shop vac'd the sink. After getting most of the water down and sucking a little up the drain the pump kicked in and did it's thing. (I had previously testing the pump by letting water run and did so again after the washer problem, it is happily pumping water again) I'm guessing that I somehow stopped the pump with a water seal (air lock?) or something? I'm not certain, but I believe the problem to be my lack of a vent on the washer's p trap. When the water is draining in the sink I can hear it gurgling in the pipe stack, so I know that's not right.

    What I think I need to do
    #1) I need to vent the washer P trap. I should be able to simple T off the line after the P trap and pipe it up and over to the vent. I am hopeful this fixes all my problem!

    What I don't know I need to do, but probably should do
    This is why I'm here. I thought I knew what I was doing, but obviously having missed venting the P trap I might do better to check in with some other people. Any thoughts, comments, tips? Please don't be afraid to show me something I've done wrong/offer your advice.

  2. #2
    Journeyman & Gas Fitter Doherty Plumbing's Avatar
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    Default

    Flip that wye around and run and 1.5" vent of the horizontal trap arm coming off the washing machine and tie it into the trap for the sump. Then you're golden.

    You'll be wet venting the sink through the washing machine and everything will be dandy. Some of the code guys might say something about this though because I remember reading that you can't wet vent through a washing machine down in the US.

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    Moderator & Master Plumber hj's Avatar
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    Default vent

    YOu are using a Studor type vent on the tank. It WILL NOT work, and neither will ANY other vent you connect to it. When water enters the tank there is NOWHERE for the air to go, because the Air Admittance Valve, ONLY admits air, it will NOT release it. IF you remove the trap from the sink it will work MOST of the time, as long as the water draining from the sink does not overpower the air trying to get out of it.

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    DIY Junior Member majorwoo's Avatar
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    Quote Originally Posted by Doherty Plumbing View Post
    Flip that wye around and run and 1.5" vent of the horizontal trap arm coming off the washing machine and tie it into the trap for the sump. Then you're golden.

    You'll be wet venting the sink through the washing machine and everything will be dandy. Some of the code guys might say something about this though because I remember reading that you can't wet vent through a washing machine down in the US.
    Basically I'm venting the washer line after the p-trap similar to
    http://www.terrylove.com/images/washer_rough_b.jpg
    Something like this?
    http://www.woosworld.net/images/base...02-addvent.JPG

  5. #5
    DIY Junior Member majorwoo's Avatar
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    Quote Originally Posted by hj View Post
    YOu are using a Studor type vent on the tank. It WILL NOT work, and neither will ANY other vent you connect to it. When water enters the tank there is NOWHERE for the air to go, because the Air Admittance Valve, ONLY admits air, it will NOT release it. IF you remove the trap from the sink it will work MOST of the time, as long as the water draining from the sink does not overpower the air trying to get out of it.
    According to the site these studor AAV's are a replacement for a open pipe system, but I do see what you mean about not allowing air out - and if I understand the problem correctly, I've airlocked the pump tank behind all the water trying to get in - so I need a way to let the air out of the tank so the water can get in to trigger the pump. (When I sucked the water out of the sink it lowered the pressure enough that the air was then able to force itself back through the sink trap and break the seal right?)

    So if this is the case and I actually had a proper open air vent then it would work - even though I've not vented the p trap after the washer? Or would venting the line as here
    http://www.woosworld.net/images/base...02-addvent.JPG
    Allow it to work with the AAV in place? Is there a way to correct what I have short of taking off the AAV and making a vent to my roof? (This does not excite me at all!)

    Another thought - I happen to be right below the kitchen sink (which if I understand the terminology is wet vented as there is no separate vent line) - could I tie my vent line into the kitchen sink and it would then share the wet vent? I'm not sure this makes sense or works, but I've seen several places where the talk about tying into another sink to make things work so I'm not following how.
    Last edited by majorwoo; 11-17-2009 at 09:19 AM. Reason: typo's

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    Homeowner geniescience's Avatar
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    Default

    are these pipes shown in your 3 images an independent system, not connected to the rest of the house plumbing? Answer this first, as this information determines a lot.

    You're making progress. But the vent concern hj explained is still there.

  7. #7
    DIY Junior Member majorwoo's Avatar
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    No, the only connection to anything else in the house is the discharge pipe from the pump going out to the septic tank. I hope that answers the question? I installed everything you see and simply discharged it into a 2" line that was already there (where the washer was previously discharged).

  8. #8
    Journeyman & Gas Fitter Doherty Plumbing's Avatar
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    Quote Originally Posted by majorwoo View Post
    According to the site these studor AAV's are a replacement for a open pipe system, but I do see what you mean about not allowing air out - and if I understand the problem correctly, I've airlocked the pump tank behind all the water trying to get in - so I need a way to let the air out of the tank so the water can get in to trigger the pump. (When I sucked the water out of the sink it lowered the pressure enough that the air was then able to force itself back through the sink trap and break the seal right?)

    So if this is the case and I actually had a proper open air vent then it would work - even though I've not vented the p trap after the washer? Or would venting the line as here
    http://www.woosworld.net/images/base...02-addvent.JPG
    Allow it to work with the AAV in place? Is there a way to correct what I have short of taking off the AAV and making a vent to my roof? (This does not excite me at all!)

    Another thought - I happen to be right below the kitchen sink (which if I understand the terminology is wet vented as there is no separate vent line) - could I tie my vent line into the kitchen sink and it would then share the wet vent? I'm not sure this makes sense or works, but I've seen several places where the talk about tying into another sink to make things work so I'm not following how.
    Oh I didn't know you were using an AAV!!!!

    Think about an AAV as an air check valve. It is designed to let air in but not let air out. If it let air out you'd get sewer gas smells from it and then what's the point of having one at all.

    So basically you are trying to vent the fixtures through the sump discharge line which is impossible because the sump will always have water in it and the air won't force it's way through the water, through the pump, through check, and so forth.

    You really should have your vent tied into a vent that goes through into fresh air.

    To answer you question about wet venting a sump through the kitchen sink.... DON'T DO IT!!!! I have never even hear or seen something like this attempted because it's really just bad piping practice. You would need to tie the vent for the sump into the vent for the sink ABOVE the flood level rim of the sink.

  9. #9
    DIY Junior Member majorwoo's Avatar
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    Right, so the AAV only lets air in, I understand that (And I understand now why I need to let air out). What I'm trying to gather is when an AAV does work? If they market it as a replacement to an open air vent (and if I understand things) if I had an open air vent things would be working, they sure don't seem like a replacement at all? From the studor site, "The Studor AAV can be used in lieu of expensive and complex plumbing (open pipe) vent systems that penetrate roofs of buildings. "

    Also, I put a washer/dryer/sink/toilet/tub/shower in our basement with my Dad years ago - I don't recall ever seeing these fresh air lines. I'm thinking we must have wet vented it all(perhaps we had used larger pvc?), so why is it that I can't get away with that here? (This is just me trying to understand things, not just being argumentative)

    Thanks for your help guys!

  10. #10
    Moderator & Master Plumber hj's Avatar
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    Default vent

    You cannot get away with it here, because you cannot violate the basic laws of physics. Two objects, air and water, cannot occupy the same space at the same time. The AAV solves one equation, "water out/air in", but cannot do the corrolary "water in/air out". Once you eliminate the air lock, everything will work properly without ANY additional vents. But conversely, you can install ALL the additional vents you want to, but if they do not connect to an atmospheric vent you will still have the same problem. You could connect to the sink VENT at a point 6" ABOVE the countertop, but that would usually involve a great deal of remodeling.

  11. #11
    Journeyman & Gas Fitter Doherty Plumbing's Avatar
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    Quote Originally Posted by majorwoo View Post
    Right, so the AAV only lets air in, I understand that (And I understand now why I need to let air out). What I'm trying to gather is when an AAV does work? If they market it as a replacement to an open air vent (and if I understand things) if I had an open air vent things would be working, they sure don't seem like a replacement at all? From the studor site, "The Studor AAV can be used in lieu of expensive and complex plumbing (open pipe) vent systems that penetrate roofs of buildings. "

    Also, I put a washer/dryer/sink/toilet/tub/shower in our basement with my Dad years ago - I don't recall ever seeing these fresh air lines. I'm thinking we must have wet vented it all(perhaps we had used larger pvc?), so why is it that I can't get away with that here? (This is just me trying to understand things, not just being argumentative)

    Thanks for your help guys!
    AAV work fine as an individual vent and that's about it (IE vents only 1 fixture). They can also be ok when used to feed air to a wet vent. But I try not to rely on them too often.

    And maybe you and your dad did the plumbing wrong years ago For a wet vent you still need a vent :P

    It's not working for you because you are dumping everything into the sump which is a sealed unit. So you're creating a postive pressure inside the tank that keeps the water in your sink.

    You could install 2 more AAV one each on the washer and sink. But having 3 AAV in one application is extremely DIY. I'd strongly suggest you tie the venting in properly for the best function of your design.

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    DIY Junior Member majorwoo's Avatar
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    Ok, then help me understand this.

    I need air to get out of my system, if I take my studor off I have an open air vent (and we expect the system to work). However, since the only source of actual septic air would have to come back through the check valve only open when the water is being pushed by the pump (ergo no gas coming in that way) what prevents me from simply taking the studor off? The only gas I can see getting out the vent that way is something that came from the sink or washer already so it would have already been able to escape into the air?

    If I did run the vent line to the roof (Ugh, I may need a pro for this, I'm not comfortable putting holes in my roof) do I still need to vent the p trap from the washer similar to http://www.terrylove.com/images/washer_rough_b.jpg or is it getting vented via the pump box vent itself since the pump vent is between the sink trap and washer trap?

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    DIY Junior Member majorwoo's Avatar
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    Quote Originally Posted by Doherty Plumbing View Post

    You could install 2 more AAV one each on the washer and sink. But having 3 AAV in one application is extremely DIY. I'd strongly suggest you tie the venting in properly for the best function of your design.
    Again, just trying to understand here but that would give me 2 more sources of air coming in - and I need to get it out right? (So how would it help?)

  14. #14
    DIY Junior Member majorwoo's Avatar
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    Ok, well proof of concept (for me really, you seem sure) - without the AAV everything works fine, I don't even get water in the sink. So I need a line to my roof, which I'm not sure I'm up to do myself.

    Thanks for the help.

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    Homeowner geniescience's Avatar
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    two problems. One, can you send a vent pipe outside to get an air exchange? (thru the same hole where you have the discharge...?) See hj's post about air coming out, to replace water coming in. This is a biggie. And 2. your previous post with a link showing new venting for your washer P trap is a good way to vent after the P trap, otherwise that P trap is too high, since without venting it should be on the same level as its discharge to the pump tank, while with venting it could be positioned higher. But without a solution to #1. above, you will have only solved a portion of the air exchange problem, although it might be possible to get lucky and have a balanced vent loop regardless, like what's under some island sinks. That's about all I can say.

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