Roughing in Heights..
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That's considered an S trap in that configuration, no?
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Yes. From that picture, that would be considered an -S- trap.
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Sometimes life is such, you just have to live with it. Of course you don't want to siphon a trap.
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The last time I checked, the maximum tailpiece length is 18”; 24” for a washing machine standpipe. It’s considered a “fouling area”, not protected by the p-trap. All that cat food sticking to the inside of the pipe can start to smell.
And the inspectors don’t like offsets of the tailpiece.
Vertical offsets on the trap arm can and will cause the p-trap to be siphoned.
Good eye, mad dog.8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
Boy did I get this wrong, I though you guys were talking about roughing it in the mountains (heights)
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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A good chance it is not vented, just tied into a waste pipe? Ideal location for an auto-vent if that is the case.
Maybe it was roughed in for a deep laundry tray sink :)
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
So this brings me to a question I have been meaning to ask for a long time. I put a 3 bowl sink in my kitchen with one very deep bowl. I roughed it in low, they connect in the wall with a tee and a cross stacked if I remember then that goes up to a mechanical vent in the attic. The rough in is low enough that the drop under the sinks is still probably around a foot. It seems to drain poorly, like it is slow to drain until almost like a siphon gets started. Is the big drop in the tailpiece before the p-trap a problem as far as drainage goes?
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Those auto vents tend to stick after time. A hot attic may shorten the life even more. Either they stick closed and don't vent, or the disc warps and they allows sewer gas to seep out. The Studor brand seemed to last the longest.
I think washers are allows an 18- 24" standpipe, not sure about lav sink tailpiece length. The long tailpieces tend to stink, toothpaste and other slime accumulates. A dose of BioClean now and then, at nightime, helps eat away the scum :)
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream
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I wonder if that was roughed in Before making the vanity ADA compliment.
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It is possible the mechanical vent clogged itself with cellulose insulation too. I shoved the vent on the end of a piece of pipe up the wall cavity and in to the attic with the intent to eventually remove the mechanical vent and tie it in to the vent stack in the attic. Sticking would maybe explain very nicely why it seems to go through periods of draining poorly and draining great. It is pvc that connects in to a galvanized stack in the basement. I replaced the part in the wall with pcv up to well above where it was a vent only while I had the kitchen wall open. It would have required bringing the vent through a lot of framing to tie the vent in within the wall.
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when people custom build a really deep P trap, that can slow down a drain. A long tailpiece with a standard p trap should not cause an intermittent drain issue
If the vent is in the attic, offset it and go through the roof near the peak?
Auto vents are a last resort and should be easily accessible for service and replacement Under the vanity for example
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
A restricted vent might cause a slow drain condition? It will cause the trap to siphon but how does it slow the draining water down? Lots of air should not be going down with the water while full flow draining. The water pulls air after it at the end of a water slug going down. A partly clogged or a poorly pitched drain pipe would be my first suspects for slow draining. Anyone have a logic explanation (physics) of how a clogged vent slows draining?
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I'm not sure how a stuck AAV could possibly make a sink drain slow. I could see it allowing the trap to be siphoned dry but that's about all.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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I just noticed I said something very similar as you many hours later.
I'm not sure how I missed your post.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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@mattmia2 Like this?
What is the drain size? What about the dirty arms, left and right?
Does the drain tie into the old kitchen drain? Or does it join a larger drain.
When drained individually, do they all drain at the same speed?
Take one of the p-traps off to allow air in to see if one of the other sinks drains better.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
Wet vents should be 0ne size larger.
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Chris..Take a straw and put down in to soda....finger over top ...them lift out keeping finger of top. You'll pull the whole slug of soda out w it. Hold in a vacuum...super slow drainage.
Take finger off...whewwww
Vg drainage..you added a Vent Mad Dog
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Alan..."Dirty Arms"?? Is that California Plumbing vernacular? Mad Dog
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With an open drain in a sink you don't have a finger on the straw. It'll just vent right from the sink, no?
Some could argue a sink or tub will drain substantially quicker without a vent because gravity is actually siphoning the water out of it.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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."Dirty Arms"?? Isn't that what deodorant is for? That's why I take a bath once a month whether I need it or not.
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If that mechanical vent is in the attic it is probably too far away to vent properly. Especially if it is a single-fixture vent.
This type of vent is rated for a certain fixed amount of venting measured in drainage fixture units. A large whole-house mechanical vent should be in your attic space. If it's not and is a smaller single fixture-rated vent, then you will want to change it.
Or, add a small mechanical vent at the kitchen sink for extra venting.
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What does the distance above the drip line have to do with it? It is only venting the sink.
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AAV's are generally rated to open at 0.25"WC.
Code requires no more than 1"WC of vacuum at a trap.
I've never seen a maximum distance specified on AAV's?
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Welp looks I need to do more reading
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Yes, that's what we call them. Dirty, because they get………
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab1 -
I actually have a bathroom sink that does that.
It's one of those cheesy ones without the built in overflow. The thing is, it seems like air gets stuck in between the trap and the sink it self and I guess bottlenecks it? I saw the same exact behavior where I used to work with a similar designed sink, no overflow. If you remove the stopper assembly while it's draining you'll get a big burp of air and it'll drain beautifully.
In my case, the P trap goes into a 2" vent which is wide open right to the roof and to the 3" it ties into via a wye. It's 100% piped correctly and there's no way that's causing the issue.
It's confused me for years because I've never seen a kitchen sink behave that way and they don't have overflows.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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This is all a trap arm. There is a length & slope for a trap arm. No 90 deg allowed, max is 45 deg.
This is how you do it.
Or
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Which code is that from Homer?
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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When I learned it, it was the Uniform Plumbing Code, which was what my jurisdiction followed.
If the length of the trap arm discharge is below the trap weir, there may be a siphoning of the trap, think S trap. I think that was the reasoning.
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Only once when I had no other choice did I use an Air Admittance Device inside a cabinet as high as it would go, connecting it to the trap arm because of the slope of the trap arm.
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See i have kitchen sinks that do that but it seems more like it is a bubble of air gets stuck between the j bend and the wall but i suppose it could be in the long tailpiece. If i remember if you take out the strainer it starts draining fast so I guess it could be in the tailpiece(I usually just wait instead of sticking my hand in the water and then having to wash my hand). The bowls are 3 different levels and the shallowest bowl has a disposer on it. I keep the stopper in the disposer in the open position to prevent silverware and such from falling in.
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Water moves down a pipe at its own head. That's why drain pipes are sloped. A level pipe isn't going to drain as fast as a vertical pipe. The right slope is important. 1/8" drop per foot is the minimum slope and 1/2" is the maximum slope for horizontal runs.
Any restrictions in a pipe is going to slow the flow thru that pipe. I have found pipes half filled with grease, ugh, or filled with garbage disposer debris that didn't drain out.
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The finger over a straw explanation for a slow drain holds no water. It doesn't represent the physics of a drain and vent system regardless of how wide spread the belief is that it does.
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The plumbing codes address the vent as a means to keep the trap from siphoning. A deeper dive explains the vent also allowing for adequate drainage. Although 2 phase flow gets complicated. Something engineers talk about.
I see the vent accomplishing multiple tasks
@Jamie Hall may know more
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream2 -
HA! This started about rough in heights. @hot_rod Are you suggesting an improper vent creates restrictive two phase flow in a residential sink drain? Is this phenomena relevant? Small pipe diameter" and "has to push air out of the way"? I'm not sure how the phenomenon applies to code compliant sink drain and vent systems. It seems to be related to vertical drops but I don't claim to understand it well. Maybe I'll learn something down that rabbit hole. "Because of the collapse of the quantum wave function" is always good "it's complicated" reference material 😁
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