Max vertical distance out of p-trap before going into trap arm

**Hammerlane** · 03-31-2012, 07:40 AM

In the following photo disregard the dishwasher drain hose and address the vertical distance between the green lines.

Is there a max vertical distance the water has to rise out of the trap before going into the trap arm?

**Hammerlane** · 03-31-2012, 07:41 AM

I think ideally the setup should be like this: but wanted to know if there is a max height like on post #1

**Hackney plumbing** · 03-31-2012, 07:46 AM

What your asking is the maximum trap seal. I believe the answer is 6"

Thats from the bottom of the trap to the outlet.

hj · 03-31-2012, 08:35 AM

There is a "normal" max/min dimension, but in your case we CANNOT disregard the dishwasher drain because it is connected WITHIN the trap seal, so your dishwasher COULD siphon the trap seal into the dishwasher during every cycle after the water is discharged. Actually, none of the rest of the installation is proper anyway, because that appears to be a "vent tee" rather than a "center outlet baffle tee". I would take a SawZall to the whole thing and start over. Why is the horizontal line at that height. How about a picture from a little further away so we can see the entire system from the bottom of the sinks down.

**jimbo** · 03-31-2012, 09:31 AM

UPC 1005.0 says trap seal shall be 2" min 4" max unless a deeper seal is found to be necessary by the AHJ.

As a practical matter, I believe experience tells us that a deep trap seal will drain more slowly. And as hj noted, the location of your DW tie in would be an absolute disaster.

hj · 03-31-2012, 02:04 PM

As a practical matter, a deep seal trap will drain almost, if not exactly, the same as a standard seal, unless you get ridiculous on the depth of the seal. The Tyler deep seal cast iron trap is 3 1/2" to 4" deeper than the conventional one. But, in this particular case, there is no need to go "deep seal" if it were plumbed correctly.

**Hammerlane** · 03-31-2012, 02:18 PM

Originally Posted by jimbo

UPC 1005.0 says trap seal shall be 2" min 4" max unless a deeper seal is found to be necessary by the AHJ.

As a practical matter, I believe experience tells us that a deep trap seal will drain more slowly. And as hj noted, the location of your DW tie in would be an absolute disaster.

Thanks Jimbo.

And to the others: This is not my setup. Something I found online at another site and I was wondering about the height of that trap seal. The people on the other site were not providing answers so I figured I'd come here.