Would this be a proper way to run drain line for basement sink?


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Old 10-17-20, 08:02 PM
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Would this be a proper way to run drain line for basement sink?

On the other side of my mechanical room's wall, we are putting in a small powder room. The sink is going to be on the wall below the boiler valves, which is represented by my awesome graphic. I was hoping to just pop the drain through that wall and down to the current ABS drain line in the photo. The drain just services the boiler and the hot water tanks relief valve, so hopefully never used besides testing the valve. The slope is adequate from there going to my stack.
  1. Would this be appropriate to do?
  2. Should I have a little trap on the bottom of the vertical pipes coming down from my tank and boiler? I was once told I should, but these would be dry since those relief valves hopefully aren't releasing water often. So, would that do anything?



 
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Old 10-18-20, 05:13 AM
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Where is the vent?

What is the upturned portion of pipe for?
 
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Old 10-18-20, 02:22 PM
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The sink will be vented with a studor. The upturn pipe in the pic is the drain for the water heater's relief valve.
 
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Old 10-18-20, 02:27 PM
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There has got to be a trap somewhere on that line already (not pictured) or you would be venting sewer gas out the hot water heater overflow opening. Assuming that is the case, you may not put a second drain with a trap on that same line.
 
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Old 10-18-20, 02:41 PM
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There has never been any smell down there and when you trace the current pipe back, it connects into the waste line from the upstairs sink/shower. Then it drops into the ground next to the stack. There is a floor drain there, so would it be possible that is where the trap is for the current pipe? Regardless, that line can't have a second trap on it so I would need to run new pipe. Correct?
 
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Old 10-18-20, 02:52 PM
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The floor drain should have its own trap.
 
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Old 10-19-20, 10:01 AM
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I too find it odd that the overflow pipe doesn't have its own trap.

If I was in your situation, I would install the new sink as you have planned, using a combo wye to connect to the horizontal drain pipe.
I would then add a trap to the existing standpipe for the water heater. You may have to keep that trap filled, but with the way it's installed, your new sink will probably keep it filled.
And ensure the pipe is sloped properly. It's hard to tell from the pic if it has a slope to it at all.

Also realize, that standpipe probably doesn't meet code as it's not 18" high. I wouldn't lose sleep over it, but it will be the first thing to overflow if there's a clog in the line. That's the only downside of keeping it.
 
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Old 10-19-20, 07:22 PM
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Thanks for the feedback. We only have 1 floor drain down there which is about 5ft away through finished basement. That is why the "clever" way they ran the drains for the water heater and boiler. I have a few follow up questions below.

We will have an upflush macerator toilet in the the bathroom there so we don't need to tear up concrete in the finished basement. I can run the drain from the sink to the toilet, which will then pump it up and out. We just don't want the grinder/pump running every time we just use the sink and we are unsure if that will be the case? Anyone know if this would be the case since this may be the easiest option.

From my calculations, I need a 3.5" drop, which this pipe has. I have attached a drawing of the situation since the pic can't show it all. The sink would be connecting in between two standpipes because my boiler is on the right. So the boiler definitely wouldn't maintain water in a trap that I add on to it. Would this impact the situation at all?

Lastly, so I would be able to put another trap on this line? Reading online and feedback here, it is confusing if I can do this or not.

Thanks for the feedback.





 
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Old 10-20-20, 10:26 AM
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I can run the drain from the sink to the toilet, which will then pump it up and out. We just don't want the grinder/pump running every time we just use the sink
No, it's like a typical sump pump. Once the reservoir fills to a certain level, the pump goes on. The only difference is the pump is intended to pump more than just water. So if you wash your hands, the pump won't trigger on unless the tank happens to be almost full already.

As for the traps, the rule is each fixture requires its own trap and you can't have 2 traps for one fixture.
If you install the sink the way you have it drawn, you'd need 3 traps, one for each standpipe and one for your sink.
Another option would be to trap both standpipes together, and a second trap for the sink.

Regardless whether you install the sink, I would still trap the standpipes, you've been lucky that you haven't been getting sewer gasses out of them.
 
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Old 10-27-20, 10:11 AM
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Thanks. It seems like the best option is the easiest and just connecting into the toilet. I will take your advice with the standpipes as well.
 
 

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