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leifweaver · Feb 20, 2010, 06:35 PM

I am remodeling my home and need to tie into the existing vent and drain of a toilet - BUT - there is NO existing vent on that toilet and the soil pipe drops vertically from the toilet. So, can I a vent tie into that vertical pipe? If not, how do I correct this? If so, how far below the toilet can I tie in? I have some joists and ducting that is in the way of the first 16" below the toilet, but can be moved if manditory.

massplumber2008 · Feb 20, 2010, 07:00 PM

Hi Leifweaver...

If you're lucky then the toilet is vented by the sink drain/vent... called wet venting a fixture. Here, the sink vent acts as the vent for the toilet (and can for the tub/shower, too) when not in use and unless you're a monkey trying to wash his feet in the sink while using the toilet this will vent the toilet properly... vent is increased to 2" for this to be correct.

That vertical drop in the toilet is allowed as the toilet has an integral trap... the vent or the wet vent (sink drain) just needs to roll above the center line of the horizontal toilet drain to be a proper vent (or wet vent).

Now, so I can really help you...tell me...exactly why are you trying to connect into this drain with a vent...hmmm...??

MARK

leifweaver · Feb 20, 2010, 07:20 PM

Originally Posted by massplumber2008

If you're lucky then the toilet is vented by the sink drain/vent.
MARK

Hi, thanks for your time, but perhaps I was unclear. The toilet drain drops straight from the toilet for a full floor and hooks into the main sewer drain, just before it exits the house. Currently, there are NO other lines that come off this 13' vertical drop.

Originally Posted by massplumber2008

Now, so I can really help you...tell me...exactly why are you trying to connect into this drain with a vent...hmmm...??MARK

So, the reason I want to hook into that drain is that I think that the toilet needs a vent (even though it has a built in trap). In the past, I have always had the vent at the end the toilet's drain's horizontal run, so the vent comes off the TOP of the sanitary T. What I want to know is: Can I have the vent come off the 45 of a sanitary Y?

massplumber2008 · Feb 20, 2010, 07:52 PM

O.K.

Curious... where do the sink and tub or shower connect into the drain system if not into the drain pipe that connects to the toilet?

Otherwise, to answer your question...

You need to connect a vent within 8 feet of the toilet... best is to roll a sanitary tee fitting at a 45 degree angle on the horizontal pipe. Traditionally, we connect into the horizontal drain for a toilet and not on the vertical riser going to it.

Back to you...

leifweaver · Feb 20, 2010, 08:02 PM

Massplumber, thanks for your help. To answer your question, this toilet is stand-alone. It is not part of a full bath. It is a water closet that comes off the entry from the barn. There is a sink in the entry (it used to be a milking room I think), but the sink just drains into the center concrete barn drain, while the toilet drains goes straight down into the basement and hooks into the house septic.

I am not sure what you mean by "best is to roll a sanitary tee fitting at a 45 degree angle on the horizontal pipe." There is no horizontal pipe. I can connect within 8 feet of the toilet without a problem, but only on the vertical riser. Does code require that I create a horizontal drain to connect too, and then jog it back to the original drain?

massplumber2008 · Feb 20, 2010, 09:19 PM

Believe it or not, code does require that a vertical tailpipe/drop cannot exceed 24"... so in this case, yes, you would be required to have a horizontal portion to the drain pipe for this toilet.

I can't imagine the pull on that toilet with a 13 foot drop and no vent... must suck the integral trap almost dry... yes?

I would start by adding a vent. If that doesn't improve things then you may need to consider adding a horizontal component to the design. The vent would then connect into the horizontal drain at a 45 to 90 degree angle off the pipe... see picture.

Back to you...

leifweaver · Feb 20, 2010, 10:02 PM

I just went out to check it out. It does suck the trap nearly dry. I want to bring it up to code as I am doing other work, and it is easy to do right now, so in addition to adding the vent, I will put in the horizontal run, as is standard. I am glad that code allows for a 2' drop, as I need about 14" to get around the joists. Then it is all pretty straight forward.

Thank you so much for your help. It is an odd situation, and I definitely needed some advice!