How to add AAV

[saxsellers]

My wife and I just bought a home (built 1901) and are having an issue with our double kitchen sink barely draining and backing up if the faucet is on for about a minute or more. We checked to make sure there wasn't a clog. The run from the kitchen to the vent stack/main drain is 25+ feet, and I think we have a good enough slope (though that's another thing I need to verify). I'm thinking my best option is to install an AAV, but not quite sure how to make the plumbing work under the sink due to the tight plumbing. There actually is another vent pipe for the washer about 10 feet away, but would have to find a way to tie in through the basement (which I'm thinking won't work). I believe the drain pipes from the sink are 1 1/4" and at the bottom expands to a 1 1/2" pipe.
I've included a picture of the trap. Thanks for any help you can provide!

 

[Terry]

Normally you would have a santee with the AAV above that. The trap going straight out from the santee.

What you have is 1.5" tubular before it hits the PVC, which may be 1.5" too.

2" from the floor with 2" cleanout.

 

[Sponsor]

 

[saxsellers]

Normally you would have a santee with the AAV above that. The trap going straight out from the santee.

What you have is 1.5" tubular before it hits the PVC, which may be 1.5" too.

I think I've got it...thanks!

 

[saxsellers]

Another quick question...I'm afraid the P trap arm is going to be too long to squeeze between the tailpiece and the drainpipe. Can I swing the first part of the P-trap to the left and rotate the trap arm portion back around to the right without causing a draining problem?

 

[Reach4]

Can I swing the first part of the P-trap to the left and rotate the trap arm portion back around to the right without causing a draining problem?

Yes.

 

[Michael Young]

My wife and I just bought a home (built 1901) and are having an issue with our double kitchen sink barely draining and backing up if the faucet is on for about a minute or more. We checked to make sure there wasn't a clog. The run from the kitchen to the vent stack/main drain is 25+ feet, and I think we have a good enough slope (though that's another thing I need to verify). I'm thinking my best option is to install an AAV, but not quite sure how to make the plumbing work under the sink due to the tight plumbing. There actually is another vent pipe for the washer about 10 feet away, but would have to find a way to tie in through the basement (which I'm thinking won't work). I believe the drain pipes from the sink are 1 1/4" and at the bottom expands to a 1 1/2" pipe.
I've included a picture of the trap. Thanks for any help you can provide!

First, you have an S-TRAP (which is not allowed by code). No big deal. Just plumb it the way the picture showed. Second, in your installation, the drain piped is too close to your sink basin. You're going to hit the bottom of the sink if you go straight. Buy a street 45 and a regular 45 so you can dogleg that straight pipe over a bit so the AAV will fit.

 

[saxsellers]

Thanks all for your reply! Put in the AAV today (if any plumber took as long as me, they’d be in the unemployment line!) , but the only change in the backup is that it drains a bit faster. When I turn on the faucet wide open into the left sink, the right sink begins backing up (along with left sink) within 10 seconds. Ideas? I checked the slope on the drainpipe and made some height adjustments bc I could tell there were some low spots, but that’s 15 feet down the line...I don’t think enough time to cause a sink backup in less than 10 seconds? Thanks again for your help.

 

[Reach4]

You have a clog.

2 inch pipe holds about 0.1633 gallons per foot. So if it were a total clog, you could estimate how far along the clog is. But your clog is not total, so there will be some water getting by the clog as you are filling the pipe.

Clogs often happen where the pipe turns from vertical to horizontal. You may be able to stick a medium Brasscraft drain bladder down your pipe and clear it, or you can snake it with a big-enough snake.

Vents will not cause slow draining. The purpose of the vent is to keep the trap from siphoning and letting sewer gasses out.

 

[saxsellers]

You have a clog.

2 inch pipe holds about 0.1633 gallons per foot. So if it were a total clog, you could estimate how far along the clog is. But your clog is not total, so there will be some water getting by the clog as you are filling the pipe.

Clogs often happen where the pipe turns from vertical to horizontal. You may be able to stick a medium Brasscraft drain bladder down your pipe and clear it, or you can snake it with a big-enough snake.

Vents will not cause slow draining. The purpose of the vent is to keep the trap from siphoning and letting sewer gasses out.

Thanks...the backup was there before, that is why I put in the vent. However, after the vent, I get the same thing. The pipe is a vertical drop to a horizontal 90 in the basement. Is my next guess to replace that 90 with a 45, 12 inch pipe, and then another 45? I do have some clean outs further down the line as well, but none at this initial 90. Maybe check the clean outs first, and if nothing there, work on replacing the 90? Thanks again.

 

[Reach4]

Is the 90 above the basement floor? If so, replacing that with a long sweep 90 or two 45s would be good. You could add a cleanout while you are at it.


My elbow was under the basement floor. What I did is saw out maybe a 10 inch section on the vertical. I stuck a Brasscraft drain bladder down, and turned on the water. Then I put that same section back in place with flex couplers.

 

[saxsellers]

Is the 90 above the basement floor? If so, replacing that with a long sweep 90 or two 45s would be good. You could add a cleanout while you are at it.


My elbow was under the basement floor. What I did is saw out maybe a 10 inch section on the vertical. I stuck a Brasscraft drain bladder down, and turned on the water. Then I put that same section back in place with flex couplers.

Like yours, it's under the basement floor, so thankfully, easy access to the pipe. If I add the cleanout, I'll be using a wye connector, correct?

 

[Reach4]

Like yours, it's under the basement floor, so thankfully, easy access to the pipe. If I add the cleanout, I'll be using a wye connector, correct?

You could. I just used the open pipe, and then replaced the sawn-out piece. You are going to need access, what, every 10 years?

You would use shielded/banded couplers. I used unshielded rubber couplings, because that was all I knew then.