How do you install one?

What do you need to installed a johnson tee for? Thanks.

John

Never ran into one in the Atlanta area. After reading all the issues, glad we just use a high loop.

I am assuming that the Johnson tee is required in your area over a simple countertop airgap (or the even easier high loop), correct?

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.

See pictures:

Hello Mrfubu,

Please open the link below will gave images of Johnson tee and other dishwasher draining system, Thanks.

John

https://www.google.com/search?q=john...h=746&dpr=1.25

Why is there a copper line coming off the Johnson T?

Hi John

The copper line is where the discharge drain from the dishwasher will connect to after the wall has been plastered and the cabinets installed. The Johnson tee is an air gap device similar to the countertop air gaps used in most states. In my state we don't use any air gap...just a high loop and I have NEVER seen an issue at all. To me these air gap devices are only good for failing and causing floods!!

Yeah. That's exactly the impression I have gotten from reading posts here for a number of years. The high loop works and is fool proof.