johnson tee Archives - Charles Buell Consulting LLC

October 3, 2012 by Charles Buell

The Johnson Tee Dishwasher Air Gap Device—some more information.

I have done several other posts about the Johnson Tee and their use as an alternative to the countertop style air gap device for dishwashers.

Johnson Tees and Countertop Air Gap Devices

Johnson Tee’s—another way to vent your dishwasher drain

Johnson Tee Air Gap Device with Decorative Cap

While I like these devices quite a lot, because they eliminate the need for having a device installed on the sink or countertop, it has come to my attention that some modern dishwashers require a 5/8” drain line from the washer. In order to make these dishwashers quieter they use less noisy motors that do not have the pumping capacity of older noisier motors. The larger size drain minimizes clogging that might result with smaller diameter drains.

There are still lots of dishwashers—even really quiet ones—that still allow the ½” drains typical of Johnson Tee’s. The problem might arise if one has a Johnson Tee installed and one buys a washer that requires a 5/8” drain line. This is not a big issue as the Johnson Tee would need to be properly abandoned and a countertop style air gap device installed. The other option of course would be to find a washer that allows for a ½” drain line.

Some of the dishwashers that I found installation instructions for that require a minimum 5/8” drain lines were GE, ASKO and Bosch—there are likely others.

Some of the dishwashers that I found installation instructions for that require a minimum 1/2” drain lines were Whirlpool, Kitchenaid and Amana—there are likely others.

There also may be different “models” of many of the manufacturers’ that either allow or don’t allow a ½” drain line.

Some jurisdictions do not even require air gap devices—or are not enforcing codes that do require them.

Every dishwasher installation’s requirements must be met regardless, and this is why installation of a dishwasher should only be done by a qualified professional.

By Charles Buell, Real Estate Inspections in Seattle

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October 21, 2011 by Charles Buell

Johnson Tee’s—another way to vent your dishwasher drain.

The other day I got a nice email from someone in San Francisco wanting to know where they could find a Johnson Tee air gap device for the dishwasher they were installing. They said they had been asking around and no one had ever heard of one. They had found a previous post that I had done about these air gap devices and were looking for additional information.

Rough-in plumbing for a Johnson Tee air gap device

These devices are a great way to vent the dishwasher as the washer will then have its own trap and you won’t have to have that unsightly cap attached to the sink or the countertop. It also ensures that the air gap is well above the sink rim. It can be vented either through the countertop backsplash or wall—or to the exterior of the home. It also eliminates one more hose running through the cabinet space under the sink.

I replied that I thought they would be readily available at Lowe’s or Home Depot type stores or just do a Google search for them.

Much to my surprise, I could not find even a hint of them on the Internet in terms of where I could actually buy one. There were several articles about them—of which several were my own blog posts.

So I went to Aurora Plumbing, one of the big local plumbing supply stores, and bought one. This was proof that I was not in the Twilight Zone or that I had not otherwise lost my marbles—well regarding this topic at least.

But to go back to the Twilight Zone a minute, a very strange coincidence occurred at the plumbing supply store. While I was at the check-out line the area rep for Johnson Industries, Inc was standing there and overheard me talking to the cashier about the Johnson Tee. It turns out that they are manufactured right here in the NW and were invented by the owner of the company, Bob Johnson, in 1979.

The device has a registered patent dated 1980, which is just about the time I started using them in my houses in the early 1980’s all the way over on the other side of the country in Oswego, NY. The rep told me that they are only sold to plumbing supply distributors—hence you won’t find them at the wannabe plumbing stores like Lowe’s and Home Depot. This explains why when you Google “buying Johnson Tee’s” there just is not very much information.

It kind of makes one wonder what else Google doesn’t know.

The devices have a UPC stamp on them and should be acceptable in most jurisdictions, so check with your jurisdiction or ask your plumber. If your plumber has never heard of them you might want to find another plumber.

***

Charles Buell, Seattle Home Inspector

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June 26, 2011 by Charles Buell

Johnson Tees and Countertop Air Gap Devices

So what the heck is a Johnson Tee?

Most people are probably familiar with the air gap device that is present at the kitchen sink that prevents drainage water from flowing back into the dishwasher (nice thought). When they are plumbed backwards they make nice little fountains into the sink.

There is another method of venting the dishwasher that, while a little less common, does the same thing—-the “Johnson Tee.” These devices have been around for quite a while—-at least the early 1980’s when I was building houses in the Oswego, NY area. With this method of venting you won’t find the washer drain connected to the disposal or drain under the kitchen sink the way it would be with the countertop air gap. It leaves a much cleaner look and doesn’t use up the extra hole in the sink—which can then be used for something else—like a soap dispenser, a hot water tap or a push button vacuum switch for the disposal—or even a filtered water faucet.

With the Johnson Tee, the drain and washer connections are all behind the dishwasher and inside the wall cavity. The actual vent portion is at the exterior of the home (although sometimes it might be found on the countertop backsplash). This is what the assembly looks like inside the wall before the wall is closed in. At the very bottom of the picture you can see where the drain from the washer will connect.

At the top is where the Tee portion goes through the wall to the exterior and will have a finish cap installed that looks like the one in this next picture.

Like the countertop type air gap device, if you see water or foam coming out of the cap it is an indication of problems with the dishwasher drain and a plumber should be called to make repairs. The biggest problem that the Johnson Tee encounters is that the holes at the exterior get painted over—-which prevents proper function—-so the holes must be maintained open. Another thing that is common is that the test caps get left in place and never properly finished.

This can be remedied by simply drilling a few small holes in the cap or by cutting the cap off and installing the more decorative type pictured above.

So make sure your house is wearing its Johnson Tee or countertop air gap device properly.

***

Charles Buell, Seattle Home Inspector

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