I am replacing a horizontal iron 1-1/2 " T that sits outside the wall between an 1-1/2 vertical drain and a kitchen sink trap. The T vents to a 1-1/2" vent line in the wall. The original 1906 install used a horizontal straight T rotated about 20 degrees from vertical to allow connection of a 1-1/4" sink arm between the T and the vent elbow. Is it acceptable to use a test T to replace the iron T? If not, should it be a wye, and if so, in which direction?
Type of Horizontal T to Vent Kitchen Sink
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wwhitney
In the Trades
I didn't follow your comment about 20 degrees, because you used the term "vent elbow". A dry vent should come off vertically (at most 45 degrees off plumb) and stay vertical until above the fixture flood rim, so I'm not sure why you'd have a "vent elbow".
Anyway, Minnesota uses the UPC. So if you have a horizontal trap arm, and you want to take off a vertical vent while keeping the drain horizontal, you need to use a wye or combo. The wye or combo is arranged so that if waste backed up into it the vertical portion, it would drain out properly once the clog is resolved.
Cheers, Wayne
Anyway, Minnesota uses the UPC. So if you have a horizontal trap arm, and you want to take off a vertical vent while keeping the drain horizontal, you need to use a wye or combo. The wye or combo is arranged so that if waste backed up into it the vertical portion, it would drain out properly once the clog is resolved.
Cheers, Wayne
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The horizontal T is out of plumb about 20 degrees so that the vent pipe (uses a trap arm to connect between top of T and the vent elbow in the wall) can allign with the vent in the wall. I'm not much of an artist but I have attached drawings to show the situation. Sounds like I will be OK using a wye that is arranged to flow back toward the wall DWV should there be a backup into the vent. Also sounds like I can't use a test T (the female thread would be more convenient). Thanks for your help.
Attachments
wwhitney
In the Trades
Terminologically, the trap arm is just the portion of horizontal drain line between the trap outlet and the vent connection. So a trap arm is never a vent.
Your 3rd picture is fine, but the vent taken off must rise to an elevation of 6" above the fixture flood rim while remaining vertical (that is, up to 45 degrees off plumb, but no more, and not horizontal). Your first and second drawings make it look like the vent turns to horizontal to enter the wall. If this is happening under the sink, rather than 6" above the sink flood rim, that is not allowed. The wall will need to be opened up and the vent line reconfigured.
However if the vent is entering the wall at a 45 degree angle above horizontal, that is allowed, as that still counts as vertical.
Cheers, Wayne
Your 3rd picture is fine, but the vent taken off must rise to an elevation of 6" above the fixture flood rim while remaining vertical (that is, up to 45 degrees off plumb, but no more, and not horizontal). Your first and second drawings make it look like the vent turns to horizontal to enter the wall. If this is happening under the sink, rather than 6" above the sink flood rim, that is not allowed. The wall will need to be opened up and the vent line reconfigured.
However if the vent is entering the wall at a 45 degree angle above horizontal, that is allowed, as that still counts as vertical.
Cheers, Wayne
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