Johnson T advice?

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P.Dieter

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In Seattle, where high loops don't give the inspectors the warm fuzzies I'm doing a kitchen w/ granite counters and I don't want the airgap on the counter and I don't care for filling the hole with a soap dispenser after final. So I'm back the the Johnson Tee (which I haven't installed in years). So I'm attaching a photo/diagram to see if I've got the plan right. Red is 1.5"ABS, Blue is 2" and black is 1/2" copper. Do I need a cleanout between the san t's? Have I got this right?

johnson_tee_hasil.jpg



Your observations are appreciated.
 
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Calif_Pilot

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I have never seen anything in the uniform plumbing code called a Johnson T..as far as i know the only approved dishwasher connection is through an airgap mounted on the countertop..let me know if i am wrong..thanks
 

P.Dieter

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calif pilot,

I don't know about wrong when it comes to plumbing but here's something from my county health folks

Date: August 8, 2005 Decision No. 05-001


Subject: Dishwasher Drainage Discharge Piping and Airgap (Johnson Tee)

Code / Section: 2003 UPC 807.4

Decision. The PVC extension of the Johnson Tee dishwasher drainage airgap may be extended to interior or exterior locations for the purpose of providing air to prevent backsiphonage. When extended to the outdoors, they shall not extend to an upper level, nor shall they extend to an exterior wall of another unit in multi-family construction. When extended to the interior, they shall terminate within the same room as the dishwasher. Solvent cement meeting ASTM D3138 may be used for the transition from ABS to PVC in a non-pressure application. Where the termination is extended to a location away from the Johnson Tee, no portion of the extension shall be trapped and horizontal runs exceeding 12-inches shall be installed with a minimum of ¼-inch per foot slope back to the Johnson Tee.


The pressurized discharge piping to a Johnson Tee drainage airgap fitting may be of copper or CPVC. Other materials may be used if approved for such use by the piping manufacturer and where the fittings do not reduce the internal bore of the piping. The drainage airgap fitting shall be located in the same room as the dishwasher.
 
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Calif_Pilot

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section 807.4 of the uniform plumbing code states"No domestic dishwashing machine shall be directly connected t a drainage system or food waste disposer without the use of an Approved dishwasher airgap fitting on the discharge side of the dishwashing machine. Listed airgaps shall be installed with the flood-level [FL] marking at or above the flood level of the sink or drainboard,whichever is higher"..
I would guess that your local Building and Safety Dept..would have jurisdiction over local codes..The Uniform code book says nothing about a Johnson tee..I would call a building inspector in your area for advice..sorry if i have confused you at all..
 

Furd

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My house was built in 1987 and there is no "visible" air gap for the dishwasher. The dishwasher drain connects to a 1/2 inch copper pipe that exits the wall just above the bottom of the sink cabinet. There is a 3/4 inch copper pipe that barely protrudes from the siding (outside) well above the top of the sink. This outside tube is definitely connected to the dishwasher drain as it rumbles and gurgles when the dishwasher is draining. This drain is about fifty feet north of the King County line. :rolleyes: I have no idea of what is inside the wall but I suspect it must be something like this Johnson Tee.
 

Terry

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In the Seattle area, an inspector with the last name of Johnson, came up with the design for the fitting.

It's my prefered way of providing an air gap for a dishwasher connection.

The drawing at the top, is a way that we used to plumb them.
Then the inspectors decided that the sink waste was too large for being used as the wet vent for the dishwasher.
Now we use a fixture cross so that neither are wet vented.
One side for the dishwasher, and the other for the sink.

johnson_tee_2.jpg
 
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P.Dieter

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Thanks Terry

I assume that I need to still have the cleanout above the cross and a vent up from there as well as a vent coming up from the sink T. And can I do the sink line in 1 1/2 abs since no DW?
 
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P.Dieter

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I'm afraid I don't know the difference. How's it configured (can't seem to google it up either)
 

Terry Love

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Have you glued it?

1) for a kitchen sink, you can have a 1.5" trap arm and vent, but it requires 2" waste

2) the way you have it pictured, everything works exept that the waste going to the sink santee should be 2", and then a 2x1.5x1.5 santee

3) or you could have put the fixture cross the same height as the sink outlet, and trap armed over with a 90 el

The center pipe from the fixture cross would have been the vent for both the dishwasher and the sink.

It would work that way. Older homes are done that way. I've never done it that way, I started plumbing in the 70's and 1.5" pipe for kitchen waste wasn't being done then.
It does look nice as far was workmanship. Fun isn't it.
 
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Geniescience

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The dishwasher drain is run with 1/2" copper with at least a 42" riser where it turns back down and connects vertically into a Johnson tee. The tee allows for the 1/2" connection on top, with a vent to the outside on the branch, with a regular 1 1/2" connection going down to a P trap which is vented normally.I found that description at https://terrylove.com/wwwboard/messages2/29837.html fwiw

Sound to me that this solves the problem of the having gurgling noise inside the house when the dishwasher is draining. I want that. It is good for all those open concept kitchens.

david
 

P.Dieter

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Terry
redone with the 2" line to the sink but now another plumber suggest that the 90 to another San T is a real no no and it needs to be done as you described in #3.

theseplumbersarekillingme. ;) ;)
 
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