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c0dist · Mar 24, 2014, 11:15 PM

Greetings all,

I just replaced the garbage disposal and realized that my drain trap is horribly incorrect. I would appreciate some advice on how to fix this (what kinds of pipe sections to connect and in what order).

The difficulty I'm having is that the existing drain is a vertical pipe coming up through the floor and almost directly underneath the sink. It doesn't lend itself to a P-trap and a horizontal section.

Thanks in advance!

ma0641 · Mar 25, 2014, 05:51 AM

How old is the house? Was this a remodel? What you have is an S trap, not code in any areas I know of. Some places will allow a retrofit with an AAV above the flood rim of the sink. I had to do that with a log home drain because there was no wall cavity to run plumbing through.

speedball1 · Mar 25, 2014, 07:48 AM

Ahh, the good old days when houses had one 4" cast iron main that went through the basement and up and out the roof. All fixtures connected directly to the main after the trap. Things are different now. You may still keep your basic configuration but you will have to add a AAV,( automatic air vent) downstream from the trap as shown in the image. Good luck, Tom

c0dist · Mar 25, 2014, 08:00 AM

The house was built in 1952. Yes, parts of it have been remodeled by the previous owners (the kitchen being one of them).

Hmm, short of ripping out the cabinets and installing a new drain behind the wall, is the AAV the only workaround here? No way to get crafty with some pipe sections to make a better trap?

I'm assuming the AAV would have to stick out above the counter top, since the sink sits flush with it? Or is this something that I can install beneath it?

Thanks!

speedball1 · Mar 25, 2014, 08:21 AM

Hmm, short of ripping out the cabinets and installing a new drain behind the wall,

NO,NO and NO! No one said anything about going into a wall. Simply install the AAV past the trap and connect back to the drain in the floor. More q2uestions? I'm as close as a click. Tom

c0dist · Mar 25, 2014, 08:53 AM

I think I understand now and will look into picking up an AAV, but just a couple more questions, please.

ma0641 mentioned retrofitting the AAV above the sink rim. I know for sure I wouldn't be able to get my wife to agree to that. Is it sufficient to keep the AAV under the sink, so long as it's a few inches higher than the trap?

Also, since there's very little space between the outlet of the garbage disposer and the drain pipe, I'm wondering how to best connect the horizontal section after the trap? Can I use a flex pipe or will that reduce the flow too much? I'm sorry I'm probably not framing my question clearly.

massplumber2008 · Mar 25, 2014, 10:47 AM

AAVs are NOT required to be run above the flood level of the sink (Brian is thinking of regular vents). AAVs need only rise six inches above the PTRAP to be a valid installation. I would cut the copper pipe lower and then get an 1.5" copper x 1.5" PVC shielded transition clamp (the fernco clamp you have now is as illegal as the whole setup), offset the pipe using a street 45 degree fitting into another 45 degree fitting and then install a sanitary tee fitting to pick up the vent and the new PTRAP. Buy a PVC female adapter and an AAV (threads into the female adapter) for the top of the sanitary tee and an 1.5" trap adapter (also called a desanco fitting) to install the 1.5" TUBULAR PVC PTRAP you'll also need to pick up. Although not perfect, it is certainly a lot closer to perfect than you are right now...;)

Mark

c0dist · Mar 25, 2014, 07:26 PM

Thanks for all the input so far; this is helping me and I've learned a lot. If I read the comments correctly, something like this is in order (excuse my hand-drawing). I tried to use the names of parts as I found them on the home-improvement store website.

Does this look about right? If so I'll commit to buying the parts and giving it a whirl.

Couple questions:
1. Is it okay to put the 45 degree street elbow directly into the shielded rubber coupler, or should it be fitted to a small section of PVC first?
2. If the disposal drain output doesn't line up with the PVC trap input when all is said and done, can I connect them with a flex coupler?

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massplumber2008 · Mar 26, 2014, 05:17 AM

The shielded clamp cannot be the clamp with two SS clamps...must be a shielded clamp that transitions from copper to PVC....see image.

You can insert the street part of a street 45 into the clamp.

You should not require the additional flex coupler if you install the sanitary tee fitting in the proper place.

Good luck!

hkstroud · Mar 26, 2014, 05:23 AM

Basic question here. If the S trap is working, that is, the trap is not getting sucked dry and creating an odor problem, why mess with it?

c0dist · Mar 26, 2014, 02:21 PM

Originally Posted by hkstroud

Basic question here. If the S trap is working, that is, the trap is not getting sucked dry and creating an odor problem, why mess with it?

Fair point; I just assumed that the current trap is no good based on what I've read. It seems to be illegal for new construction and for remodeling / repairs. Wanted to nix it now so it doesn't turn into a problem later, or if/when I go to sell the house.

A counter question: is there a way to tell that it's not working, besides the presence of an odor? Do I have a guarantee that it won't break the seal if I happen to drain a lot of water all at once? Say my wife puts in a stopper and fills the sink, then lets it all out. Or, if the dishwasher discharges a high volume of water. It seems to me like a P-trap would eliminate the guesswork (?)

I saw that they make clear traps so you can see the water seal, but that doesn't sound like a good idea for aesthetic reasons.

hkstroud · Mar 26, 2014, 02:58 PM

I say that if normal use does not create a odor problem leave it alone. If you occasionally have an odor, simple run a little water down the drain. Worry about it not being legal when you sell the house. If the trap police come knocking on your door, say you didn't know.

talaniman · Mar 26, 2014, 03:23 PM

How long have you been at this home and had problems with it? I would have assumed you tested it thoroughly already.

c0dist · Mar 26, 2014, 03:36 PM

Originally Posted by talaniman

How long have you been at this home and had problems with it? I would have assumed you tested it thoroughly already.

Haven't had problems. Just wondering how one would test such a thing? I can't "see" into the trap.

Curiosity more than need.

talaniman · Mar 26, 2014, 03:42 PM

Fill up the sink with water and see how it drains, and run the disposal with ice cubes and observe how its working.

massplumber2008 · Mar 26, 2014, 05:27 PM

Hi all!

I'm actually gonna call out my PLUMBER CARD here and I'm gonna say that if cOdist wants to remove an Strap that is illegal everywhere and is known for siphoning and allowing sewer gasses ("odor") into the home, especially if the sink is filled and drained, then I say he should continue.

COdist asked,

A counter question: is there a way to tell that it's not working, besides the presence of an odor? Do I have a guarantee that it won't break the seal if I happen to drain a lot of water all at once? Say my wife puts in a stopper and fills the sink, then lets it all out. Or, if the dishwasher discharges a high volume of water. It seems to me like a P-trap would eliminate the guesswork (?)

Sorry, nope can't guarantee that, so if you are willing to put the time and money in here, I say you do it! By your drawing, you are detail oriented and this should be a pretty quick job. As suggested by Talaniman, you ALWAYS fill the sink to the rim and then drain it to test your work any time you work on the drain/vent system of a kitchen sink. In this way you can be sure to find the leaks while it is convenient and not on say, a holiday that family has gathered and the drain chooses to back up AND the sink finally shows your leaker!! I swear, I've seen this quite a few holidays, guys!!

Anyway, that's my thoughts!!

Mark

speedball1 · Mar 27, 2014, 08:11 AM

Join DateJan 2008LocationAlex, VAPosts10,054

Basic question here. If the S trap is working, that is, the trap is not getting sucked dry and creating an odor problem, why mess with it?

1- :S" traps are against code and
2- There's always the chance that the trap can be sucked dry.
Cheers, Tom

talaniman · Mar 27, 2014, 08:20 AM

That begs the question of how it passed inspection in the first place doesn't it? If you bought it like that then someone may be liable for it's correction. Did you buy this house as is?

speedball1 · Mar 27, 2014, 01:21 PM

how it passed inspection in the first place?

Tal, You may be too young to remember when houses had a single 4" cast iron pipe that ran from the street through the basement and then up inside the rear of the house and out the roof. All the fixtures connected directly into the 4" using "S" traps. Traps were deeper back then and the fixtures vented through them. In my area of Wisconsin they were grandfathered in. This might be one of t5hose older homes that just replaced the old metal with PVC. Anyhow, why sweat it? It's vented now. Cheers, Tom

massplumber2008 · Mar 27, 2014, 05:16 PM

Yeah, issue isn't one of "liability"...issue is one of old plumbing and the fact that cOdist simply wants to update and improve the plumbing for him and his family, so I'd say it's about time to end this thread and let cOdist decide what to do next...;)

Let us know what you decide, cOdist!

Mark