Design Flaw: Air Gap on top of Kitchen Sink

[LilyT]

I've run a number of dishwashers over 40 years and NEVER ONCE had a clog in the line.

Hi Mitchell, I guess you run your dishwasher quite frequently?

I have asked my tenants to run the dishwasher at least once a week to prevent odor and drain hose clog. I even provided them cleaner brush and showed them how to unclog from the air gap. If he is a non-frequent user, I suggested him to stay on site when it drains. As you can imagine, these are too much to ask from any tenant!

I’m starting this thread because I’m seriously considering to change the air gap into a high loop.

 

[Mitchell-DIY-Guy]

...the blockages are not caused by the food crumbs coming from the dishwasher where the Bosch mesh can catch, but from the garbage disposal.

OK, this is very weird.

On the disposals I've installed recently, the attachment for the dishwasher is at the TOP of the disposal chamber. See photo.
The drain is at the bottom of the chamber; again, see photo.

That tells me you have stuff building up in your disposal chamber from not being properly disposed; or it's being partially clogged and backing up into the dishwasher drain. This is not good, and not correct, and should have little to do with how often you use the dishwasher or disposal.

The best disposal unit I've owned is about the least costly; it's the $99 unit they sell at Costco branded as American Standard. Nothing will clog that beast. The ISE Insinkerators I've had (Badgers, a series of them) all sucked. They all clogged on the slightest of things. Right now I have a GE, very small, but seems to be "bigger than it looks" and I've tried clogging it with asparagus and it ate right through it all with no issue.

Not all disposals do their job well. A good one will clear the mess with a minimal amount of effort or grinding. Maybe you need a better disposal...

As for asking your tenants to run the dishwasher once a week? Are you kidding? I run mine every other day, and there's just two of us living in the home, and we wash all pots and knives, etc. by hand. The only things that go in the dishwasher are plates/bowls and utensils.

 

[LilyT]

I'm a loyal customer of Costco products. Yes, I'm using Costco disposals in my house and my rental places. They are all installed correctly. The clogging happened in multiple properties.

In your frequency of every other day usage, I don't expect the drain hose to clog at all. Thanks for posting the picture. Yours is not even a high loop setup, but it'll be okay with your usage frequency.

There are people like me who do not use dishwasher that frequently at all. No kidding. Although I asked my tenants to run it at least once a week, I myself don't even do that - I run it occasionally after throwing a party. I'm aware of this possible built-up problem, so I would do a rinse only cycle first to test before I run it for the full cycle.

 

[Mitchell-DIY-Guy]

In your frequency of every other day usage, I don't expect the drain hose to clog at all. Thanks for posting the picture. Yours is not even a high loop setup, but it'll be okay with your usage frequency.

To be clear: the disposal of my preference is SOLD by Costco, but is an American Standard; 1.25HP model, very powerful. The same essential unit is sold elsewhere including direct from American Standard, but at a higher price.

That was a generic stock photo, not of my setup(s); I have a high loop setup in this home, and also had them in my two prior homes. I once had an air gap in a home I sold in 1992, only because the sink had a pre-made hole and I figured "what the heck" and rather than some blanking cover, put in an air gap.

If you have clogs because you, and your tenants don't run the dishwashers frequently, I'd probably take them out (the dishwashers). Why have appliances that aren't used? The chances of other problems (seal failures, etc.) are more likely to occur on something not used often than something used regularly.

On one of my homes, it was a vacation home and sometimes months would go by before we used anything. Still no clogs.

Personally I think something else is going on that nobody has put a finger on yet. Whether you use your disposal daily or weekly, and ditto for the dishwasher, should not cause clogs in the line.

 

[Mitchell-DIY-Guy]

...flow from the dishwasher will keep the line to the grinder clean, and if you add waste to the grinder while the water is running, and the grinder is on, it will flush it down the drain. The problem with the grinder putting solids back into the line from the dishwasher occurs when you over fill the grinder with it off, and then back up a bit of water before you turn it on.

Also, I install a tailpiece with the connection for the dishwasher drain, instead of hooking to the grinder. Simplifies thing in my mind.

Yes.
Yes.
Great Idea!

 

[LilyT]

On one of my homes, it was a vacation home and sometimes months would go by before we used anything. Still no clogs.

It is not practical to take out the dishwasher which will leave the weird gaping hole behind.
For your vacation home, you’re not using the disposal either so there is nothing to build-up at the disposal end of the hose.

 

[LilyT]

Yes, use the grinder always with running water, that part is clear. But it’s more common that people use the grinder with backed up water in addition to running water.
Suppose that I empty big amount of water after washing big pots or from washing vegetables in big plastic containers, and I notice water kind of drains slow, my first instinct would go turn on the faucet and reach for the disposal button, and satisfyingly watch the half-sinkfull of water to quickly swirl down. I wouldn’t wait for the backed up water to totally drains then go turn on the running water & disposal.

 

[LilyT]

Also, I install a tailpiece with the connection for the dishwasher drain, instead of hooking to the grinder. Simplifies thing in my mind.

How does this help?
A tailpiece is just a plain white cylinder tube. You add it horizontally between the disposal and the drain hose. Right? How long do you use?

 

[Mitchell-DIY-Guy]

It is not practical to take out the dishwasher which will leave the weird gaping hole behind.
For your vacation home, you’re not using the disposal either so there is nothing to build-up at the disposal end of the hose.

Obviously you replace a 24" dishwasher with a 24" cabinet, you don't leave a gaping hole.
You have a very rare issue with clogging lines. This is NOT common. You have tenants that don't use dishwashers very often, but lines that clog regularly enough for you to come here. None of this makes a lot of sense. I've never had a clogged line on a dishwasher in 40 years across many dishwashers, disposals and homes. I had air gap and high loop. I've had cheap $200 GE Dishwashers, and a $1,200 Bosch that worked for 20 years before I moved. A number of Insinkerator, GE and American Standard disposals. No issues, generally--except those ISE disposals loved to choke on things but never clogged a dishwasher line.

I pointed out that the entry point for a dishwasher hose is at the TOP of the disposal chamber. Used properly as noted in other posts, debris will clear out of the disposal, and NOT migrate its way up the dishwasher line--unless your tenants don't know how to use a disposal. They need to work with a lot of water and run until they are clean and clear.

Under a normal connection scenario, the output of the disposal goes right to your trap, and the trap goes out to your drain pipes. What @FishScreener is probably doing is installing a small tailpiece on the end of the disposal BEFORE it gets to the trap. The tailpiece he is probably talking about is something like that pictured below. This is the one normally used on a sink w/o disposal--but I think you could probably find one to fit on the drain of a disposal. In this way you are tying in after the disposal.



If this is a continuing problem I'd put the drain from the dishwasher on a separate connection away from the disposal/sink, just ensure it's on the correct side of a trap.

 

[LilyT]

Thank you for posting the picture and the detailed explanation! I see what you mean now. The dishwasher’s hose does not go to the grinder but after the grinder, this way, no build-up from the disposal which solves my issue. Make sense!

Second thought: why do we often see dishwasher drains into garbage disposal? Because sometimes there are food crumbs coming from dishwasher and it’s better to grind them before they go down the waste line. If the hose ties in after the grinder, it defeats that purpose.

My disposal is Costco’s ASD-1250. A good model but still clogs my drain hose.

 

[LilyT]

Interesting finding:

I was browsing online, just accidentally clicked into this YouTube video. GE has implemented its own high loop drain hose. Watch this:

 

[FishScreener]

The problem is caused when people overload the garbage grinder by filling it with waste before turning it on, or have a sink full of waste and water, and then turning it on.

This forces the waste back out the discharge port for the dishwasher.