How about any dishwasher brand other than Miele that has this feature and documented installation instructions stating they do not require or recommend an air gap even if it is not a drawer type dishwasher?

Do you know about the DW drain hose being looped high up under the counter before it comes down to the drain connection? This is called a "high loop"; it's not a product, it's a way of routing the drain hose.

An air gap is one step farther along the scale of protection.

Both an air gap and a high loop protect you when the kitchen's drain gets blocked (temporarily slow or totally blocked). Gray water can get into a DW and then the DW can (and occasionally does) give you lethal bacteria (which have killed people); although my writing this out is not designed to scare you, it just gives you a clear picture of some ultimate threats. Plumbing is fundamentally all about hygiene health and safety.

There was a time when this forum was inhabited by a few people who said that the backflow preventer in those Euro dishwashers gave you a form of permission to delete the air gap and sleep with a clear conscience. They may have even said that one did not need to loop the drain hose high. Some of them were vocal about the backflow valve being perfect.

Asko was one of the other Euro style dishwashers with a backflow preventer. Maybe the BSH family too (Bosch, Thermador).

None of these manufacturers will put it into writing as you asked for it: quote: "... that has this feature and documented installation instructions stating they do not require or recommend an air gap ..."

There is no way in the world that they would want to go against the accumulated knowledge of centuries of science, plumbing norms, regulatory agencies, and so on.

There is no way they would turn their valve into a selling feature, documented.

Now, it would not be their concern, if some appliance salesperson said something somewhere to someone. Not their official and documented concern.

Also, it would not be their concern, if someone somewhere got some AHJ to accept that the installation of one make or another of DW allowed the homeowner to delete the air gap. Not their official and documented concern.

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long story short:
either a high loop (which you have NOT mentioned yet, in your query about eliminating the high loop), or an air gap.

ALL dishwashers can be installed with a high looped drain hose. This is not specific to a manufacturer.

A DW with a "valve" in its hose is not true protection against gray water contaminating your DW, according to plumbers who I deal with. And this explains once again why you will never see it in writing as a feature that replaces the "need" for an air gap. It can be described in writing, but not in conjunction with the "air gap or not" debate.

Double check this on various discussion forums that plumbers inhabit. E.g. terrylove.com/forums is a good one.

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hope this helps.

The Fisher Paykel DD doesn't require an air gap--just a high loop. But if your municipality requires an air gap, they may be sticklers. In my city, you could have a letter signed by every engineer and the president of the company and the inspector still won't care. Air gap required, even if the manufacturer claims it's redundant.

I called the building inspectors and they said as long as the manufacturers instructions said an air gap was not needed, they would sign off on it.
Miele was the only brand I found where this is specifically mentioned in installation instructions.
Are there others? The salesman in the appliance showroomdidn't know of any other brand.

david _ I disagree with your plumbers regarding greywater getting back into DW's with a backflow preventer - especially Miele's. In the abstract I suppose one could dream up a series of situations coupled with failures of multiple parts in which the greywater might get in. Even in such a case , things would be so bad that an air-gap would offer no more protection and I'd have to look at the ugly thing.

So, I don't think there is no reason to not have the high loop since I want to cut noise and the high loop doesn't add any noise.
It just seems that Miele is the only brand that was designed to not need an air gap. I don't think the building code even acknowledges high loops as an option. They always mention air gaps and air gaps only if they mention anything in the code.
I just don't want an air gap unless there is a way to have an air gap and not hear loud running, gurgling water at every drain cycle in an open floor plan home.
If the building code mentioned high loops as an alternative to air gaps, then that would open many more choices in dishwashers or I might just keep my current dishwasher.

Right now, I considering upgrading from my otherwise quiet $800 3 year old dishwasher to a $1500 Miele because of the drain cycle noise.
I'm having a plumber come out and run a new drain connection from the dishwasher that bypasses the garbage disposal to see how much noise is being caused by water splashing in the disposer drain.
With that new connection to the drain line and a high loop, I could keep my current dishwasher until in breaks. I hate to buy a more expensive dishwasher and still not even have the double drawers I'd want if I got a replacement.

If you're just replacing the DW, you won't need a building permit or have an inspection. If you are doing more of a remodel that requires an inspection you can do what many others do - put in an air gap to pass inspection and then replace it with a soap dispenser.

It just seems that Miele is the only brand that was designed to not need an air gap.I've personally owned four different dishwashers in two houses (1984 Frigidaire, 1992 KitchenAid, 2003 Fisher & Paykel, 2004 GE [for only a few days until the F&P was moved over]). None of them had/have air gaps. I've never seen an air gap on any dishwasher owned by friends or family in the past 35 years, and none of them were Miele.

I already have two holes cut in the granite and one is a soap dispenser. I never use it because, even though it's pointed towards the sink, it drips and stains the granite around the sink. I don't know what to do with the air gap hole except just leave the air gap cap in place to cover the hole.

Do they make soap dispensers with long "beaks" that will extend far out enough to drip in the sink instead of around the edge of the sink? Either that or a non-drip dispenser. If so, maybe one could be dish soap and the other hand soap.

I know you can skip an air gap in any dishwasher, but isn't Miele the only brand that is actually designed to deal with that and prevent backflow into the dishwasher?

I'm not sure why this type of one way drain isn't in every dishwasher or at least every higher end series dishwasher. I can't believe some people buy $2000+ dishwashers and still listen to drain cycle noise because they used an air gap to stay within code.
Maybe they all just run to their third floor east wings of their 8,0000 sq ft mansions to escape the noise.

The high loop is a more than adequate solution with any DW - that's why other brands don't bother with that valve. My understanding is that very few places require airgaps - maybe only California? Some inspectors in CA require an airgap even with Miele and as I said above, some people remove the airgap right after inspection.

To be honest I've never seen an airgap so I can't comment on the noise but I think you're really overthinking the issue.

Why are high loops not a recognized method to meet code by municipalities?
Either they have no related code at all and don't care what you do with the dishwasher drain or they have a code that says you must have an air gap.
My city has a code requiring an air gap, but they make an exemption for dishwashers that have a built-in air gap equivalent (so far only Miele). I haven't heard of exemption for high loop.

High loops probably aren't infallible but neither are airgaps or vavles. IMHO, this is a case of over-regulation - lack of an airgap isn't going to cause a fire, explosion, or other life-threatening situation. If it were, other locales would require them as well. You've got 3 choices - put in an air gap and live with it, put in an air gap and remove it after inspection, or buy a Miele.

Some people's drains block up. The theory goes, that with a high loop, one might not be aware of contamination. But with an air gap, one sees (and becomes aware) the situation if greywater rose and spilled out.

Anyone can add a valve to the dishwasher Tee. I don't know why people aren't doing that. Backflow preventer valves.

It has been said above already that all dishwashers drain well when their hose is high looped. Miele appears to have found a way to write text that makes it look like the valve specifically works in a way that makes an air gap unnecessary. A lot of good thought went into that "stance". It's funny to see how far people take it. I'd like to see one of these valves one day. It might just be a flap, gravity-operated.

In my first post above, i spotted a typo: "eliminating high loop" should have been eliminating air gap.

Rare circumstances do occur where it is useful. Imagine someone coming home after an absence, being unaware the dishes in the DW only appear clean but are contaminated.

About backflow valves in general: the thread linked to below is about backflow prevention in supply lines.

Here is a link that might be useful: Backflow-valves-Why

weismann - the others don't have one because it cost $$$ and its hard to sell.

davidro - the valve is (or was) an assembly with a ss ball bearing not a cheezy rubber flap that'll wear out and has tons of markup. Remember this coming from a Germany company so solutions are generally over engineered which is not always a good thing.

You also don't have to put the airgap on the countertop. You can put it in the wall behind the backsplash (though you need to know what you're doing).

The other issue is that if the GD stops up, the air gap prevents the backflow into dw from flooding your kitchen. That full sink could syphon back into the dw and flood the floor. The only way that happens with an airgap is if the water is about 2" above the countertop. And if it is that high, you have much larger issues to deal with.

This is correct, weedmeister.

I also wonder why more people haven't put air gaps into the wall, or through the wall. Send the gurgling noise outside! I also don't get it why so many people put up with gurgling standpipes where their washing machine drains. Standpipes and dishwasher Tees are indirect drains, which need access to regular air / atmospheric pressure. Like with the overflow on bathroom sinks, it helps drainage when there is room air before the P trap.

I'm sure there must be ways to make indirect drains be silent without cutting them off from air (which is a no-no). I have my dishwasher teeing into my drain line near a remote P trap, and it was all designed to keep noise down. Above my DW Tee is a vertical pipe which has access to room air but it basically acts as a sound muffler. Like a standpipe with an extension that goes higher than the minimum requirements.

I really doubt the cost of adding a non-return valve type system like Miele has is really an issue once you move past the cheapest economy dishwashers sold only on price.
It isn't very difficult to explain and market it as way to prevent backflow with out the noise of an air gap on the counter either. I don't see why it would be "hard to sell" $700 and up dishwashers and especially 4 figure price dishwashers.

It is SO not difficult to explain and market it as way to prevent backflow without the noise of an air gap on the counter, that I wonder why Asko isn't doing this too. Or, maybe Asko is doing this.

But, fundamentally, it only prevents backflow partially, not bulletproofedly.

But also, it doesn't stop the gurgling noise. You will hear it in the sink drain.

Amazing, what they can imply and get the market to believe (that it makes a bulletproof and silent draining DW.) Maybe this is why no other DW manufacturer is marketing it this way.

One day when I have the spare time, I'll go dig up the Miele manuals on the web and read the line describing the wondrous advantages of the valve. I'll guess there is no health or life insurance rider warranty, and that Miele has not submitted the valve to regulatory agencies for approval as an air gap replacement.

hth

What Miele did not tell people is the fact that there are two different types of Air Gaps described in both ANSI (American National Standard Institue)/ASSE (American Society of Sanitatary Engineering) 1006 / AMAM (Association of Home Appliance Manufacturers) DW-2PR-1986 (Section 3.1.1 Inlet Air Gap & 3.1.2 Drain Air Gap) and in 2010 California Plumbing Code (Section 203.0 Airgap, Drainage & Airgap, Water Distribution).

They are for different purposes to comply to with the Codes.

Inlet Air Gap is for âÂÂprevents reverse flow from the dishwasher to the house water supplyâ per ASSE 1006-1986 Section 3.1.1 Inlet Air Gap.
Water Distribution Airgap is for âÂÂunobstructed vertical distance through the free atmosphere between the lowest opening from any pipe or faucet conveying potable water to the flood-level rim of any tank, vat, or fixtureâ per 2010 CPC 603.2.1 & 603.3.7.

Drain Air Gap is for âÂÂprevents reverse flow from the house drain plumbing to the dishwasherâ per ASSE 1006-1986 Section 3.1.2 Drain Air Gap.
Drainage Airgap is for âÂÂunobstructed vertical distance through free atmosphere between the lowest opening from any pipe, plumbing fixture, appliance, or appurtenance conveying waste to the flood-level rim of the receptorâ per 2010 CPC 603.2.1 & 603.3.7.

MieleâÂÂs âÂÂinternal air gap of greater than 1 inch on the potable water supplyâ satisfies requirements in ASSE 1006-1986 Section 3.1.1 and in 2010 California Plumbing Code 603.2.1 & 603.3.7., but

its âÂÂinternal check valve and air break on the waste dischargeâ does not satisfy requirements in ASSE 1006-1986 Section 3.1.2 and 2010 California Plumbing Code 807.4, because there is not such option described within the sections; in fact, it requires âÂÂthe use of an approved dishwasher airgap fitting on the discharge side of the dishwashing machineâÂÂ, which we can find the listing standard in Chapter 14âÂÂs Table 14-1 of 2010 California Plumbing Code âÂÂDrain Air Gaps for Domestic Dishwasher Applicationsâ per ASSE 1021-2001 !!!!!

The provision in regards to domestic dishwashing machine has been published in Uniform Plumbing Code and/or California Plumbing Code for at least 28 years (the oldest version I found is 1982 Uniform Plumbing Code). The entire sectionâÂÂs text has never changed/revised with exactly the same words from first alphabet to the last alphabet including punctuation.

so, are you trying to say Miele's valve doesn't work???