Drains - Wyes or Combos

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  #1  
Old 01-03-19, 11:14 AM
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Drains - Wyes or Combos

My home was built in 1987. Since moving in the toilets have backed up many times. Not within the toilet itself, but I am pretty sure the toilet paper and waste is becoming lodged at the many sanitary tees used. Below is a typical connection where my hall bath toilet joins the main drain line. The waste from the 1/2 bath toilet upstream travels down to this connection. Just looking at it I could see how waste and paper could get lodged where these meet.
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It would seem you would want a connection more like the Combo below.


I have many connections exactly like the first photo. Here is a basic overview shot of the last half of the main drain line.

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Could someone who actually knows how this stuff please help me understand how this should be?
 

Last edited by SJMaye; 01-03-19 at 11:35 AM.
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  #2  
Old 01-03-19, 06:52 PM
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No plumber here, but I know enough to know that the sanitary tee in the first picture isn't allowed to be laid down like that, that calls for a Y fitting .......or combo. The way it is connected it's easy to see that waste from the half bath toilet and sink just drops into the main line with nothing to point it in the right direction so it just sits there. I am sure that is where your clogs are.

Lawrosa is the resident plumbing expert here and he has been pretty busy, but he'll eventually see this thread and comment.
 
  #3  
Old 01-04-19, 04:27 AM
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Thanks, Joe. It is nice to hear I am not entirely crazy. I have done some past work with PVC plumbing and feel I could make the needed changes. I just want whatever I do to be up to code in case of any questions during a home inspection etc. A nice by-product would not to have waste backup in to the bath tub as it has!

I look forward to hearing from Lawrosa and any others.

Thank you.
 
  #4  
Old 01-05-19, 03:04 PM
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Joe is right, the sanitary tees should have never been used. It also looks like the drain down the left wall doesn't have a very good slope (though it may have to do with the photo). It's also odd that the drain makes a huge U around the basement, it seems like it should have just cut across the crawl space.

Are you considering re-piping it all? It might be worth adding a clean-out and snaking for the next time you get a clog to figure out exactly where the clog is occurring.
 
  #5  
Old 01-06-19, 05:15 AM
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Zorfdt,

Thank for your reply. Yes, I am planning on changing out the fittings that are wrong. As far as the layout of the plumbing I have drawn a simplified picture of how it is laid out. The are no Combos anywhere.

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Are you saying I would be OK with codes if I replace all those sanitary tees with combos or should I be doing something else?
 
  #6  
Old 01-06-19, 01:00 PM
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I would try to reconfigure the pipes so they don't have to go through as many turns. From the half-bath on the right, it needs to make 3 90deg turns. It would be better for the half bath to drop directly into the main run to the septic.

Same with the half bath on the left, why not just drop into the main drain that's right there. The whole round and round isn't helping things - unless the pipe really needs to follow that path.
 
  #7  
Old 01-06-19, 02:06 PM
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I understand. The thing on my mind is something I read about having too steep a grade in a drain line can be bad. For me to tap directly in the the line going straight to the septic tank would make a fairly steep grade. Does it matter in a main drain line?

If the drain lines can run at a steeper grade I could do something line this.
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Last edited by SJMaye; 01-06-19 at 02:22 PM.
  #8  
Old 01-06-19, 03:19 PM
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I have never had problems with lines pitched more than 1/4" per foot. My main drain line slopes at 4-6" per foot after it exits the house and I've never had a clog or slow drain problem. Also if you consider buildings in a city. They don't maintain 1/4" per foot. Their drain lines must fall whatever is needed to meet the sewer main.
 
  #9  
Old 01-06-19, 03:53 PM
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I've heard of code issues with too-steep pitch. Supposedly the water can run faster than the solids. I don't know the truth of this, but I probably wouldn't push it. Doing some research, I haven't been able to find any code reference, but some plumbers do report more clogs on longer steeper runs.

That said, there's no reason you couldn't do a standard 1/4"-1/2" pitch, then 90 elbow straight down into a combo into the main drain. It's how many drains tie into a main usually.

I think with a standard 10-20' run, it doesn't much matter.
 
  #10  
Old 01-07-19, 03:46 AM
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"That said, there's no reason you couldn't do a standard 1/4"-1/2" pitch, then 90 elbow straight down into a combo into the main drain. It's how many drains tie into a main usually."

Yes. After thinking about it further I came up with the same thing.

At the beginning of this I was just thinking of replacing the fittings with long sweep combos, but your idea of simplifying the system makes total sense and not with too much additional work. I guess my lack of plumbing knowledge never allowed me to consider this in the first place. Thank you.
 
  #11  
Old 01-07-19, 05:02 AM
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"It's how many drains tie into a main usually."

I just re-read this. Are you saying there are some limitations as to how many how many drains I can drop in to that main line going to the septic tank? The distance of that pipe leading to the septic tank is roughly 50 feet.
 
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Old 01-07-19, 06:21 PM
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I just re-read this. Are you saying there are some limitations as to how many how many drains I can drop in to that main line going to the septic tank?
No. I should have worded "It's how most drains drop into the main."

Well, technically there are limitations based on drainage fixture units (DFUs), but with 3" or 4" pipe in a typical residence like you have, you don't have to worry about it.
 
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Old 01-08-19, 04:12 AM
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Got it. Thank you. I begin the re-piping tomorrow.
 
  #14  
Old 01-08-19, 10:28 PM
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I, for one, have never had to clear a drain that clogged due to 'too much pitch'. Pitch is good for a drain -- flat is bad.

The more downhill, the better, imho.
 
  #15  
Old 01-12-19, 07:54 AM
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Update. I got the first phase of these changes done this week.
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I am getting ready for phase 2, connecting the hall bath directly to the same main drain line.

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I have a question with regard to changes in direction. Combo vs. 2 - 1/8. I was looking at the need for cleanouts and saw the pic below and it made me wonder which was better for flow; a single combo fitting or 2 - 1/8 bends as shown.
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I just want the crap (sorry) to flow. Do you guys have any opinion on which is better?
 
  #16  
Old 01-12-19, 08:50 AM
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I use both interchangeably so it usually comes down to which I have on hand. If I'm buying the fittings I'll usually pick a sweep 90 or two 1/8 bends as there's less work involved with installing the sweep 90 but because of so many more joints in the two 1/8 bends it has a lot more adjustability if your having trouble to get things to line up.

And, I'm a big fan of clean outs. I install them anywhere I think they might be helpful in the future. I'd much rather snake out a drain in a dirty crawl space than remove a toilet and deal with a poo covered drain auger in the finished part of the house.
 
  #17  
Old 01-12-19, 09:35 AM
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I'd much rather snake out a drain in a dirty crawl space than remove a toilet and deal with a poo covered drain auger in the finished part of the house.

I'd also install a cleanout regardless of which diagram you follow and it it ever needs to be snaked, I would call a drain cleaning company.
 
  #18  
Old 01-12-19, 01:00 PM
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Hey guys, thanks for the replies. Based on what you have provided I will put in a clean just prior to a "sweep 90". I assume this means a long sweep 90 elbow.

A question regarding long sweep 90s. When looking at them at home depot I expected to see a very large sweep 90 degree elbow. What I found them calling long sweep looked remarkably like the standard 90. So much so that I had to check the box part number to the part to be sure.

Should the long sweep 90 be significantly different looking?
 
  #19  
Old 01-12-19, 02:50 PM
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Yes, a sweep looks very different than a standard 90. To me a standard 90 looks like a fitting while a sweep looks like someone bent a piece of pipe.
 
  #20  
Old 01-12-19, 02:56 PM
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I think for this one I will try going down to my local plumbing supply store and check theirs out.
 
  #21  
Old 01-14-19, 05:02 AM
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I went by HD and laid the standard 90 side-by-side with the long sweep. See below. They do look different.

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I guess what confused me was I was expecting a much wider sweep like the combination wye.


I wish I could lay one side-by-side with a long sweep 90. The sweep on the combo fitting is much larger.
 
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