Laundry utility sink replacement

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Tanner, Feb 18, 2018.

  1. Tanner

    Tanner New Member

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    Feb 10, 2018
    Location:
    Denver, CO
    I've got an old laundry sink that I'm looking to replace with a Mustee utilatub model 19. It has roughly the same volume, and I'd like to add a faucet. My current sink tends to fill up 80% of the way when doing laundry (standard non-HE washing machine), and tends to drain relatively slowly (5-10 minutes). I noticed that it currently has no P-trap, and seems to run up once reaching a cleanout, so I was wondering if I need to add a pump to it. I've added some pictures, but it runs from the sink, down to a cleanout which then runs up towards the adjacent bathroom where there is a vent and then the drain runs underneath the slab.

    Do I need a pump on the sink since the trap may not be above the nearest vent? Also am I going to have issues dealing with that galvanized pipe between the sink and cleanout? I was wondering if there is a cleaner way to arrange how the washing machine drains into the sink, if it could tie into a trap or if I should still have it drain into the sink directly. Any suggestions on how to properly replace this sink are appreciated.

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  2. cacher_chick

    cacher_chick Test, Don't Guess!

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    Water does not flow uphill. It appears to me that the sink is connected to a line going into the floor. If that is connected to the building drain, the sink needs to have a trap and a vent to keep sewer gas from coming back up the line. If the drain is slow, it may be that the galvanized pipe is largely clogged with rust and debris.
     
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  4. themp

    themp Member

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    Could be that the uphill portion of the line is providing a trap so sewer gases do not flow back out the sink. The weight of the water in the sink pushes it past the up hill(that is why it is slow to drain). In the one picture there is another vertical pipe into the floor. What is that draining? Or is that a vent of some sort?
     
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    FWIW, drain lines normally are never full. Therefore, a drain cannot provide a trap. A trap, typically one shaped sort of like a P on its side, will hold water, but when you add water, it will flow through, retaining enough water in the trap to do just that...trap that water to provide a gas seal from the sewer.

    Galvanized piping is a failure waiting to happen. Depending on use, it can take a long time. To replace that sink, you'd want to either run a vent line or, if your local area allows it, you could get by with a mechanical vent called an air admittance valve (AAV). You'd also need to add a trap.

    You should plan on replacing all of that galvanized piping into the vertical drain line. You'll need a BIG wrench to unscrew it. Once you get it off, you'll probably find that the insides is all rusted and clogged with lint and threads from the washing machine, which is why it runs slowly. When done, the basement will probably smell better, too.
     
  6. dj2

    dj2 In the Trades

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    From Jad: "You should plan on replacing all of that galvanized piping into the vertical drain line. You'll need a BIG wrench to unscrew it."

    I would definitely replace the galvanized. Trouble is, too much torque, and the galvanized pipe might snap, break or refuse to rotate at the thread in the CI fitting. Then it will be a much bigger job.
    I would cut it straight with a recip saw about 6" away from the hub and use a galvanized to PVC/ABS Fernco connector/adaptor. Then run a plastic pipe, trap and AAV from the new sink to the Fernco connector.

    Note: when you cut the galvanized, deburr it, so it doesn't damage the rubber connector.
     
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  7. Tanner

    Tanner New Member

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    The vertical drain line that goes into the floor just to the right of the sink (left of cleanout) is the drain for the kitchen sink and dishwasher directly above the utility sink. I looked at the roof and it is vented for that drain. The drain line that goes to the cleanout and then to the hub where it ties into the main stack and goes under the slab again and has a larger vent on the roof.

    I pulled the cleanout apart today and snaked the sink to the cleanout. There was just a ton of sediment in the cleanout and the pipe diameter seemed pretty small compared to the outer diameter. I plan on cutting the galvanized pipe near the stud (~6" from the hub) and using a fernco coupling as suggested. After snaking it, I realized that the slow drain is more likely due to the lack of venting on the sink. Are Studor vents acceptable to use in CO? I looked at their site and it says the vent needs to be at least 4" above the drain of the device. So would this be 4" above the bottom of the sink?

    So cut the galvanized pipe near the hub, add a P-trap to the sink and then a Studor vent as close to the trap as possible? I assume I don't need the cleanout if I add a trap? Or would it make more sense to cut the vertical drain and tee the sink drain into it for a vent?
     
  8. Reach4

    Reach4 Well-Known Member

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    Slow draining is seldom caused by lack of venting.
     
  9. Tanner

    Tanner New Member

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    Since the sink and toilet behind that hub drain just fine, would you suspect it's blockage between the cleanout and hub? Is there any way to test whether venting will help without actually adding an AAV to the line?
     
  10. cacher_chick

    cacher_chick Test, Don't Guess!

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    The sink is required to have it's own vent to prevent the trap from being siphoned. This fact is regardless of whatever might be wrong that may be causing slow draining.
     
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    A trap without a vent usually gets siphoned dry, thus, the trap doesn't always work as required. YOu need an actual, atmospheric vent, or, if allowed, an AAV will work. The AAV is a one-way air valve...if there's suction on the line from waste draining by the end of the pipe, instead of sucking the trap dry, air will get pulled in via the AAV.

    To work properly, the AAV must be on the sink's drain line before it turns down. Depending on the size of the drain line, there is a maximum distance. On 2" pipe, that's 5', it's shorter on smaller pipe and longer on larger pipe. IOW, it doesn't necessarily need to be all that close to the trap, just before that drain line turns down within the limits.

    YOu want to make sure the coupling you use is both the right size (pvc and the galvanized are likely different OD's), and is the reinforced, banded version with a metal sleeve...not an all rubber one. This is so that it can keep the ends of the pipes aligned. Once you cut the pipe, you may find that the end going into the stack is all corroded...if so, you really should replace it.
     
  12. Reach4

    Reach4 Well-Known Member

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    Location:
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    Is there any way to make a drain run slowly by having a blocked plumbing vent servicing the sink?

    If you were feeding water into something like an unvented septic pit, that could cause slow draining. But I don't think a drain at or near that sink can cause slow draining. For a situation like that, and AAV would not help.

    When you make that cut, I would shove a Brasscraft medium drain bladder in there, as far down as it wants to go, and turn on the water for a while. See if you can move more of the crud downstream. You can use mechanical means too. But for amateur use, that bladder can be easy and useful.

    You could maybe pick up a small also, but a medium should be able to go into a 1.5 inch pipe.
     
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