Air Gap needed/required?


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Old 03-04-08, 05:50 PM
N
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Air Gap needed/required?

Hi,

I'm installing a completely new kitchen. I was advised I may be required to install an airgap for my dishwasher. My understanding is that to install one you need to drill through your countertop and install the airgap on top of the counter.

Contemplating drilling additional holes in my new granintertops and is making me nuts and I'd like to avoid it if at all possible.

From the research I've done so far, it looks like it's there to prevent a siphon forming, drawing water from the sink, or sink's trap(???) back into the dishwasher. Suppose I put in a separate drain line for the dishwasher, i.e. a separate vertical drop to the main horizontal trunk in the basement ceiling? This way, the sink drain and the dishwasher drain are isolated?

Another possibility is that the counter backs up to a wall. Could I install the airgap inside the wall cavity so the airgap is above the top-of-sink level?

Any advice would be appreciated.

thanks
njescapee
 
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Old 03-05-08, 03:59 AM
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Some local codes require them some don't, check local code. Our code does not, but I have never understood the reason for them. Anyone??????
 
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Old 03-05-08, 09:36 AM
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Just as Bill says, some jurisdictions require them and some don't. And yes, they are to prevent siphoning of water back into the dishwasher.

What is typically done where an air gap is not required is to run the dishwasher drain hose upward and then loop it back down to the drain connection. This sort've accomplishes the same thing.

I would not put an air gap inside a wall. Probably against code, but in any event they need to be cleaned once in a while and water would back up inside the wall if your sink drain line got clogged.
 
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Old 03-05-08, 12:01 PM
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Somewhere around here (can't find it at the moment) I have a picture from a home inspection of a counter-top air gap with a blockage on the drain side backing up *lots* of water onto the counter-top.

At least when this happens, the air-gap is usually near the sink, and with luck the water (or most of it, anyway) drains to the sink off the counter. - that's why indirect waste receptors are supposed to be in plain sight, and why I would not want to put an air-gap in the wall...
 
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Old 03-08-08, 04:28 AM
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Michael, if you find that picture, pls post. Every now and again my wife finds a small amount of water in the bottom of the dishwasher and I'd like to fix this.

Thanks,
DFS
 
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Old 03-08-08, 06:13 AM
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FWIW, there are lots of reasons why water can be left in bottom of a dishwasher after the last cycle: misadjusted cycle time, misadjusted float switch, clogs in the pump mechanism, clogs in the drain line, obstruction at the food waste grinder knockout and attachment of the drain to the wrong side of trap come to mind offhand. Also, on most models of dishwashers there is normally water in the sump (to prime the pump) but usually itís out of sight.

If you ask in an appliance thread, someone can likely held you track down the source of your problem.
 
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Old 03-08-08, 06:42 AM
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Dishwasher require an indirect drain. It is not a siphon issue, but simply to prevent water in a clogged sink or drain from backing up into the dishwasher, since, to paraphrase an expression from my submarine days, that would result in poop in the people tank....not good!

The UPC requires an air gap, some other codes do not.
The inspector does not really care about your granite counter top!

Before air gaps came around, dishwasher drains were high-looped under the counter top, which was pretty effective unless the sink was filled right up near the brim.

You can't put anything in the wall. I have seen dishwashers piped to an indirect drain on the OUTSIDE of the house.


Yes, if the downtube from the air gap to the drain gets plugged, the dishwasher pump will cause water to spill out of the air gap onto the counter top, or into the sink. That happens often enough that putting and air gap under the counter or in the wall, would be a disaster.


Not to chastise you personnally, but to others just starting to plan a project, you do need to be aware of codes and other requirements before you get started.

For another example, when planning for granite, not all faucets will mount. You need to find a faucet with a long enough shank, or an available extension kit. You can't believe how many people show up at the plumbing store..." my plumber is here to install my faucet, and it doesn't fit in my granite"!
 
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Old 03-08-08, 03:35 PM
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FWIW - I've lived in 5 states over the past 7 years - and California is the only place that required one..... check the codes locally - you might be able to avoid a headache....


Or - visit a new home and see if the builder installed one... if they don't have to - they won't.
 
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Old 03-12-08, 09:50 AM
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I would high loop the DW drain so that the top of the drain line is higher than the top of the sink. There are probably millions of DWs installed that way.

If an air gap is required in your area and the inspector catches it - then you can call a granite guy to come drill your countertop. If it's not required or it is and the inspector misses it, you're ahead of the game.
 
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Old 03-14-08, 06:57 AM
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Originally Posted by 594tough
to paraphrase an expression from my submarine days, that would result in poop in the people tank....not good!
Man, I haven't heard that expression in a long time (SSBN-654, 1970-1975).
 
 

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