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Old 03-10-2008, 12:29 AM
jpk jpk started this thread
 
Location: Redmond, WA / Henderson, NV
531 posts, read 1,155,574 times
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Default Does Las Vegas code require an air gap above your sink for dishwashers?

OK, I thought maybe someone on this forum might be a plumber or just happen to have the answer.

I have a new construction home in Henderson and I want to install a reverse osmosis drinking water tap at the kitchen sink. Problem is, there is a dishwasher air gap installed at the extra sink hole where I'd like to put the RO water tap.

Where I'm from an air gap is for old outdated dishwashers and plumbing and is not required for new systems. Is the air gap in my new home there just as a precaution or is it actually required by code? I thought it was kind of quaint to see an air gap installed with new plumbing and appliances.

I'd like to remove it and connect the dishwasher drain hose directly to the food disposer to free up the spot on the counter top for a RO tap. But if its code then I guess I will have to get a hole cut into my granite for the tap.

Thanks!!
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Old 03-10-2008, 04:21 AM
 
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When I was building homes there in the late 90's it was a code requirement. I don't know what plumbing code they're following now, but I know that in GA (where I am now) they're no longer required. I'd probably just play it safe and either punch a hole in the granite, or punch another hole in the sink- whichever is easier.
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Old 03-13-2008, 07:34 AM
 
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The air gap mechanism that is currently in the hole you explained IS required by code to be there. It is the Nat'l Buliding Code.

It is totally unnecessary to have it, you could run the DW hose straight to the disposal, but you might find come home sale time that code compliance laws will require you to return that to it's original condition. Again, totally overkill to have the air gap.
You could remove the air gap from the sink top, and install it just under the sink, as code requires that the air gap be 6 inches above the fixture it serves. (Which in this case is the pump from the DW, which is 6 inches above the floor.)

You could get handy, and either creat a new hole in the sink for the water spigot, (by way of renting a hole punch to get through the stainless sink - assuming it is stainless) or just drill a new hole in the counter (if it's laminate/wood) right directly next to the sink in order to still be in the sink cabinet.

Good luck.
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Old 03-13-2008, 12:31 PM
jpk jpk started this thread
 
Location: Redmond, WA / Henderson, NV
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Thanks for the info. I think I'll just move the air gap under the sink and but the RO water tap in the hole.
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Old 03-13-2008, 07:21 PM
 
Location: Las Vegas, NV
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im confused - i thought the point of the air gap was this. The drain for the dishwasher connects to the plastic air gap, and the hose to the disposal also connects to the plastic air gap. So, when the dishwasher motor drains the water, it drains water into the disposal....

However, if there was a blockage, in the disposal, which is common, the water would backup and then overflow out through the air gap into the other side of the kitchen sink that has a drain.... therefore, no flooding.....

so why would you NOT want this protection?
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Old 03-14-2008, 08:48 AM
 
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You are correct in your schematic vegas_4u except...

The air gap does not connect to the non-disposal side of the sink.

IF the disposal were to back up, the dishwasher would not drain correctly. You would notice it in the side of the sink that the disposal is on, by obviously gross water sitting in the sink. BUT the disposal in an of itself IS an air gap. If you've ever looked at the disposal, you'll notice the inlet for the dishwasher waste hose is a good 2 inches ABOVE the outlet of the disposal itself, thus creating the air gap required. Basically it's double protected by installing the mechanical air gap ABOVE the kitchen sink. It's redundant.

Different parts of the country do things different ways. Vegas is on the Nat'l Building Code, which obviously requires the mechanical air gap. Parts of the country that do not go by the Nat'l Code (They usually have their own code) only require the drain hose for the DW be connected to the disposal, but the kicker is that the hose has to be run to the highest available point underneath the sink. (Like it needs to touch the under side of the counter), thus making it almost impossible for the DW hose to back up and drain back to the DW pump, before noticing it in the sink.
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Old 03-14-2008, 09:07 AM
 
Location: Slaughter Creek, Travis County
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Henderson has adopted the 2006 International Plumbing Code. However, this a single family dwelling so the 2006 International Residential Code is applicable.

IRC Section P2717.1 requires either a air gap or integral backflow preventer for the water supply serving the dishwasher. For disposal of the wastewater an air gap is not required but a single trap with a minimum diameter of 1 1/2 inches is requird.
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Old 03-14-2008, 09:44 AM
 
Location: NW Las Vegas - Lone Mountain
15,757 posts, read 19,764,773 times
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Quote:
Originally Posted by jpk View Post
Thanks for the info. I think I'll just move the air gap under the sink and but the RO water tap in the hole.
That you do not want to do..Easily get a blockage that floods the cabinetry...note that an inspector may well pick up such an event...even if it happened only once. May also dump enough water under sink to get a little mold going and give it that musty smell. If you decide against cutting the hole run the discharge direct to the disposal without an air gap.

Note that a granite guy can easily cut the hole if you wish.
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Old 03-14-2008, 04:50 PM
 
Location: Las Vegas, NV
120 posts, read 248,114 times
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Quote:
Originally Posted by pipingplumber View Post
You are correct in your schematic vegas_4u except...

The air gap does not connect to the non-disposal side of the sink.

IF the disposal were to back up, the dishwasher would not drain correctly. You would notice it in the side of the sink that the disposal is on, by obviously gross water sitting in the sink. BUT the disposal in an of itself IS an air gap. If you've ever looked at the disposal, you'll notice the inlet for the dishwasher waste hose is a good 2 inches ABOVE the outlet of the disposal itself, thus creating the air gap required. Basically it's double protected by installing the mechanical air gap ABOVE the kitchen sink. It's redundant.

Different parts of the country do things different ways. Vegas is on the Nat'l Building Code, which obviously requires the mechanical air gap. Parts of the country that do not go by the Nat'l Code (They usually have their own code) only require the drain hose for the DW be connected to the disposal, but the kicker is that the hose has to be run to the highest available point underneath the sink. (Like it needs to touch the under side of the counter), thus making it almost impossible for the DW hose to back up and drain back to the DW pump, before noticing it in the sink.
Makes sense, I just wanted to clarify one item. When I said that water will drain to the other side of the sink, via the air gap, during a blockage in the disposal or disposal line, I was assuming the air gap would be installed in its "normal" location, which is on top of the countertop, right by the edge of the other side of the sink. So with a clogged disposal or disposal line, Ive seen water pumping out the air gap..... the dishwasher keeps pumping the water out, and it flows out the air gap then flowing down the edge of the countertop into the other side of the sink and go down that drain.......

It would seem to me, regardless of the codes, the air gap installed in its traditional location seems like a good idea in the event of a disposal line blockage.....
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Old 03-14-2008, 04:57 PM
jpk jpk started this thread
 
Location: Redmond, WA / Henderson, NV
531 posts, read 1,155,574 times
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Quote:
Originally Posted by olecapt View Post
That you do not want to do..Easily get a blockage that floods the cabinetry...note that an inspector may well pick up such an event...even if it happened only once. May also dump enough water under sink to get a little mold going and give it that musty smell. If you decide against cutting the hole run the discharge direct to the disposal without an air gap.

Note that a granite guy can easily cut the hole if you wish.
Yeah, I thought of the same thing and so I will just run the hose directly to the disposer like I expected it to be.

And vegas_4u, the air gap is always on the right side, which is where the disposer almost always is. Which is why I asked the question to begin with beause it seemed like a pretty outdated approach with modern dishwashers and the prevalence of disposers that act as an air gap.
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