Kitchen Sink Drain

marcopolio · 11-29-2012, 03:13 PM

I am having a few plumbers come by my place to quote on what it would cost and how they would plan on running a new section of plumbing. However I am not well versed in the world of plumbing so I'd like to know a little before they stop by.

I have a kitchen sink that has been moved and it needs to run to the main stack. Here is a drawing showing the existing floor joists, the existing drain and where the new drain is. What would be your plan of attack to run a new drain?

I am guessing it would use 1-1/2" pipe and it would run 48" to the right and then a 90 degree elbow to have it run to where the old drain started? Could you even do a 90 degree elbow on a drain? Or cut through the joists to have it run directly from the new drain to where the old one is?

I won't ask what would a plumber charge, as I'm sure the rates vary.

tylernt · 11-30-2012, 01:30 PM

The drain needs to be vented near the sink. A quick search suggests a 1.5" drain needs a vent within 10 times the diameter of the pipe, so, within 15" of the P-trap.

Even with a 3" pipe you only get to run 30" before venting, so I don't think that 48" + 90" run isn't going to fly without adding a vent.

Assuming you can add a vent at the new sink location, I don't think the 90° bend is a problem if a sweep ell is used and there is adequate pitch everywhere. However you'd better ask a real plumber to be sure.

marcopolio · 11-30-2012, 03:20 PM

Quote:

Originally Posted by tylernt

The drain needs to be vented near the sink. A quick search suggests a 1.5" drain needs a vent within 10 times the diameter of the pipe, so, within 15" of the P-trap.

Even with a 3" pipe you only get to run 30" before venting, so I don't think that 48" + 90" run isn't going to fly without adding a vent.

Assuming you can add a vent at the new sink location, I don't think the 90° bend is a problem if a sweep ell is used and there is adequate pitch everywhere. However you'd better ask a real plumber to be sure.

Yep no worries about the vent, there is a 1.5" dia vent going through the wall which will be connected after the p-trap in the cabinet via a sanitary T.

**TheEplumber** · 11-30-2012, 08:02 PM

Quote:

Originally Posted by tylernt

The drain needs to be vented near the sink. A quick search suggests a 1.5" drain needs a vent within 10 times the diameter of the pipe, so, within 15" of the P-trap.

Even with a 3" pipe you only get to run 30" before venting, so I don't think that 48" + 90" run isn't going to fly without adding a vent.

Assuming you can add a vent at the new sink location, I don't think the 90° bend is a problem if a sweep ell is used and there is adequate pitch everywhere. However you'd better ask a real plumber to be sure.

FYI- Your quick search was not thorough enough. UPC allows 42" trap arm for 1.5" and 6' for 3"

marcopolio · 12-03-2012, 10:03 AM

Thanks for the advice. Plumber is routing it the 48" to the right, with 1/4" slope per ft. When it changes and goes down, he'll be using two 45 degree bends. From there it will have 1/4" slope per ft all the way to the main stack.