air gap device Archives - Page 2 of 2 - Charles Buell Consulting LLC

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.

Johnson Tee Air Gap Device with Decorative Cap

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.

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Charles Buell, Seattle Home Inspector

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August 2, 2011 by Charles Buell

Air gap devices

While it is most likely an excellent idea for any Bungee Jumper to have a proper “Air Gap”—-that is not the kind of air gap I am talking about here. I am sure most of you recognize the little chrome shape cap located on your Kitchen sink or countertop. This “thingy” is called an Air Gap Device and assists in proper drainage of the dishwasher. Many jurisdictions require them nowadays. Water coming out of the cap during operation of the washer is signaling a plugged drain—-and cleaning is necessary.

Some jurisdictions also allow a “high loop” under the sink to do this job but it never actually gets the drain above the flood rim of the sink so in the event of a blocked drain from the sink water could flow back into the dishwasher.

But this post is not about the device on top of the countertop. It is about the part of the device “under” the countertop. Because of its location, behind the sink, access and installation become difficult. The hoses from the washer to the air gap device, and from the device to the drain connection, should be properly connected with hose clamps. When the connections are not properly connected, or only loosely tightened, the hoses can work their way off the device resulting in leaks under the sink. Sometimes these small leaks go un-noticed for long periods of time.

It is a good idea for the home inspector to check these connections to make sure they are in place. In this picture we see the “camera-eye” view of the device attached to the underside of the countertop. One can see that the black hose is barely holding onto the turquoise colored air-gap device—ready to pop off entirely—and certainly ready to leak.

In this next picture we can see the hose clamps stacked on top of each other at the drain connection—with signs of past leaks.

As a side note, there is another issue here that is totally unrelated to the Air Gap Device. The connection of the black ABS plastic pipe to the white PVC plastic connector is not allowed in most jurisdictions. I know in my own area, that even though there are adhesives that claim to be satisfactory for both types of pipes, it is still not allowed. In this instance, the black adhesive used on this installation is NOT the correct adhesive. I guess the thinking behind the prohibition of joining the two types of pipes is that the jurisdictional inspectors don’t want to be in the business of determining if the proper adhesives were used.

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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.

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Charles Buell, Seattle Home Inspector

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