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adrianmariano
02-11-2007, 06:51 PM
So as far as I can tell, the dishwasher works OK. But the drain line is kind of screwy. The dishwasher drains into the disposal but the pipes go through the basement and then come back up into the kitchen. In the basement I can see first a white corrugated plastic pipe which then transitions to 1/2 inch copper which transitions to 3/4 inch copper which transitions to 7/8" rubber. I assume this must have arisen through some series of incremental changes to existing stuff since obviously nobody would put in something like this.

Now I'm about to redo the kitchen sink, so if it needs to change, now's the time. On the other hand, if there's really nothing wrong with this setup, why mess with it. So the question: is there anything wrong with this setup?

Here are pictures. First the overview picture:

http://members.cox.net/jsam/plumbing/overview.jpg

Next close ups showing left the left side:

http://members.cox.net/jsam/plumbing/left.jpg

middle:

http://members.cox.net/jsam/plumbing/middle.jpg

and right side where it goes back up into the kitchen:

http://members.cox.net/jsam/plumbing/right.jpg

Dunbar Plumbing
02-11-2007, 07:02 PM
Those pictures are going to end up in a terrible discoveries album.

jimbo
02-11-2007, 07:35 PM
First, I will assume from this lashup you have no airgap, so there is always a risk that dirty sink water will overflow back to the DW. Second, that big dip will always hold dirty water, and is a smell and health hazard.

Verdeboy
02-11-2007, 07:37 PM
Was that house owned by Rube Goldberg at one time?

Gencon
02-12-2007, 03:26 AM
The problem I see, other than the obvious, is that a dishwashe drain line is required to go up at least 20" before connecting to its termination.
Is there a way to run this line through the back of a cabinet somewhere?

The big box stores carry a heavy rubber type hose sold as "dishwasher drain hose".It might be a good idea to make this drain all one piece as well.

adrianmariano
02-12-2007, 05:38 AM
I think it's just 50 years of incremental changes, no need to invoke Rube Goldberg.


The problem I see, other than the obvious, is that a dishwashe drain line is required to go up at least 20" before connecting to its termination.
Is there a way to run this line through the back of a cabinet somewhere?


When you say the drain line must go up 20" before connecting to its termination...well, doesn't it do that? I mean, it goes up into the kitchen cabinet all the way to the top of the cabinet before connecting to the disposal.

I think that, depending on where the drain line starts, it would be possible but difficult to run this line through the back of a cabinet. The line would have to make a sharp 90 degree bend.

I'm not sure if I can put in an air gap because I already have the sink (18 gauge stainless) and it doesn't have a hole for the air gap. I seem to recall reading that it was very difficult to make a hole in a stainless sink.

harleysilo
02-12-2007, 07:35 AM
Hold on there for a second....

"I'm not sure if I can put in an air gap because I already have the sink (18 gauge stainless) and it doesn't have a hole for the air gap. I seem to recall reading that it was very difficult to make a hole in a stainless sink."

The air gap is nothing more than running the diswasher drain line up higher than the spot it actually drains into to, so if it drains into the disposal, part of the drain needs to be run typically in a upside down U shape higher than the disposal.....

adrianmariano
02-12-2007, 07:39 AM
http://terrylove.com/images/sink_dw.jpg

I thought an air gap was a little device a couple inches high that sits on the sink which the dishwasher drain connects to.

From what I have seen, people refer to looping the drain hose up above the disposal as a "high loop" and it is not as good as an air gap. Right now my dishwasher drain features such a loop.

harleysilo
02-12-2007, 07:40 AM
oh, well ignore my post then, i've not heard of an air gap you set on your sink. Sorry! But could you not mount said device underneath sink?

Randyj
02-12-2007, 08:06 AM
I had a guy try to get me to install an air admittance valve where the top of the loop would be... he referred to it as an "air gap".. twisted my brain on that one. I backed out and he did it all himself. He was trying to figure out how to mount it and I was trying to figure out why he needed it... said the "instructions" showed that he needed one. My idea of an air gap is where a drain terminates about 1" above a cup or funnel looking thingy, usually a 3" or 4" PVC increaser/reducer to a 2" pvc drain pipe.

http://i149.photobucket.com/albums/s41/mastercrafts/Lake%20House%20building/PLUMBING/airgap.jpg

jadnashua
02-12-2007, 09:51 AM
The air gap and high loop are two different things. The air gap is code in some places, and not a bad idea anywhere - it provides positive protection from getting overflow crap back into the DW, a high loop usually does the same thing, but not always.

Making a nice clean hole in SS sinks shouldn't be too bad. A bi-metal hole saw will work, but a punch is better. The punch will cost more, but you might be able to rent one. The punch is a two part device, with a cutter on one side, and a cup on the other. The cup is sized so that the cutter just fits into it when you tighten the bolt. You drill a hole for the bolt, assemble the cutter on one side, the cup on the other, and then tighten the bolt. It makes a nice clean hole fairly quickly.

jadnashua
02-12-2007, 09:54 AM
WHen I moved my DW, I used pvc with a brass barbed hose connector at each end to connect to the GD at one end and the DW at the other. The inspector accepted it, and it has been working for a few years without problems. My kitchen is a small U, with the DW directly across from the sink - with the door open, it is basically right next to the sink.

Verdeboy
02-12-2007, 10:02 AM
I think it's just 50 years of incremental changes, no need to invoke Rube Goldberg.

Sorry, but I've not seen such an unusual drain for a dishwasher before.

Usually, the dishwasher sits right next to the sink it drains into, and it's a short run with a dishwasher drain hose into some sort of air gap and then into the drain.

There are two kinds of air-gaps: The kind that sits on top of your sink and the "high-loop" kind that is under the sink. There has been such heated debate in this forum on which one is better that I won't even recommend one over the other, except to tell you that you do need an air gap of some kind. As far as drilling through stainless steel, it takes about 20 seconds with a good bimetal hole saw.

markts30
02-12-2007, 01:27 PM
As far as drilling through stainless steel, it takes about 20 seconds with a good bimetal hole saw.
I agree with this however...
Go slowly and use a lubricant/oil to keep the blade cool - other than that, have fun...LOL

SteveW
02-12-2007, 02:02 PM
I had a guy try to get me to install an air admittance valve where the top of the loop would be... he referred to it as an "air gap".. twisted my brain on that one. I backed out and he did it all himself. He was trying to figure out how to mount it and I was trying to figure out why he needed it... said the "instructions" showed that he needed one. My idea of an air gap is where a drain terminates about 1" above a cup or funnel looking thingy, usually a 3" or 4" PVC increaser/reducer to a 2" pvc drain pipe.

http://i149.photobucket.com/albums/s41/mastercrafts/Lake%20House%20building/PLUMBING/airgap.jpg

That's the kind of arrangement I used for the drain for my water softener.

adrianmariano
02-13-2007, 04:05 AM
My dishwasher is separated from the kitchen sink cabinet by a fairly large corner cabinet. There is no room in my kitchen to have the two side by side. So running through the cabinets would mean going through the back of that corner cabinet.

So is the high loop adequate, or should I really put in an air gap on top of the sink? (Current installation has a high loop.)

Verdeboy
02-13-2007, 10:37 AM
High-Loop: If your sink backs up above the level of the high-loop, dirty water will drain into your dishwasher. The high loop comes to within an inch or so of the rim of the sink, so the backup would have to come up to the rim of the sink and beyond for this to happen.

Mounted Air-Gap: Dirty water will never back into your dishwasher. However, if the inlet into your garbage disposal gets plugged with debris, water will spew out of the air-gap onto your counter and onto the floor.

You decide. Also, check the code in your state if you can.

geniescience
02-13-2007, 01:23 PM
Adrian, have you mentioned somewhere above whether or not you will have a disposer?

Without a garbage disposal, you can eliminate the device known as an air gap, but you can still have an air gap! If the sink's P trap is several inches below the sink, just Tee your dishwasher drain in under the sink, several inches above its P trap. That is enough air space to do the job. The air is in the 1 1/2" drain pipe above the P trap.

That is what I have. The "T" has a slight slope to it. It's copper or brass. From there, a rubber hose loops high (from the Tee) and then down to the dishwasher.

When the dishwasher drains, I can hear it in the kitchen sink. Occasionally a few drops of rinse water splash upwards too. The noise is loud; my machine is 24 years old.

I wonder if modern dishwasher make the same amount of noise when they drain. Nobody here talks about noise as being a problem... but it sure IS a problem in an open space kitchen. Even the fridge is too noisy, at night when everything else is quiet.

David

Gary Swart
02-13-2007, 03:49 PM
Seems to me this subject has been beat to death! Yes, the drain needs to be totally redone. The fact that the DW is some distance from the sink is really irrelevant. You just run a hose through the back of the cabinets to the sink. I see no reason why the hose could not be under the floor. There are 2 choices to prevent a clogged sink drain from backing up into the DW. The simplest is to loop the hose and fasten it under the countertop and then into either the garbage disposal or, if no disposal is used, into a special tee with a stub for the hose installed in the sink drain above the trap. The other way is to install an air gap on top of the sink. The pros and cons of these have been discussed, but in fact either will work. For what it's worth, I've use a loop on my DWs for 35 years and have yet to have a problem. Main thing with using the loop is to attach it to the underside of the counter in such a way that it can not kink. Pick a way that will work best for you.

geniescience
02-13-2007, 09:13 PM
ok, i have now read a bit about "a possible cross connection or a possible back flow" when no air gap is used, with a disposer. There were 6 threads in the last two years relevant to air-gaps. I didn't see clearly whether or not there was a risk of a possible cross connection or a possible back flow when there is no disposal.... so I am still unclear about that.

Master Plumbers have responsibility and public health to deal with, so safety dictates including an air gap with a garbage disposal. I did see that "plumbers" are divided over this issue; and codes too.

david

Gary Swart
02-13-2007, 10:18 PM
If you can explain to me just how it would be physical possible for water in a clogged drain could rise above the level of the sink and into the looped washer hose, I will gladly eat crow. Now I realize as a professional you are required to follow local codes and use an air gap where code requires, you must admit that air gaps are not required everywhere. I sure don't want to start a stupid war over this, so this will be my last comment to this question.

Verdeboy
02-14-2007, 10:05 AM
I'm on your side, Gary, but here are two ways it is theoretically possible for the water to backflow over the high loop into this dishwasher.

1. The backup comes up to and over the rim of the sink.

2. You have pots or dishes blocking the drain, forcing the contaminated water to follow the path of less resistance.

geniescience
02-14-2007, 10:46 AM
umm, I think it is good to let Master Plumbers keep their approach to public safety, and let air gaps "exist".

What I cannot figure out, is why nobody has ever suggested plumbing the Teed'd-air-gap in the drain pipe "below the sink but above the trap" when you also have a garbage disposal!. It works for the situation where there is no disposer, so why is it never suggested for a "with disposer" situation?

What am I missing here?

David

adrianmariano
02-15-2007, 07:08 AM
I don't think I understand why the "teed air gap in the drain pipe" is any different than just having the garbage disposal act as an air gap.

I'm also not sure I understand why it's bad to have the dishwasher drain line go through the basement. I mean, will there be that much less water sitting in it if I route it behind the cabinets? Presumably the water that's going to be sitting in there is the rinse water anyway.

Is my installation bad because it (1) goes into the basement or (2) because it hangs down so low, or (3) because it has several different kinds of pipe.

If (2) I could easily change it by installing a new hose that I attach to the joists in the basement so it's not hanging down so low. If (3) I could get a new hose long enough to make the full run. If (1) then it's considerably more work as I have to figure out how the hose can be routed through the cabinets and drill holes through the cabinets and such. I don't want to do that unless there's a good reason to go to all the trouble. (I'm supposed to finish this job in one day so we can use the kitchen again.)

How sharp of a bend can the drain hose make without causing trouble?


Yes, the drain needs to be totally redone. The fact that the DW is some distance from the sink is really irrelevant. You just run a hose through the back of the cabinets to the sink. I see no reason why the hose could not be under the floor.

I'm a little confused by this. Right now the hose is under the floor, which appears to be considered part of the problem.

Dunbar Plumbing
02-15-2007, 07:16 AM
I don't think I understand why the "teed air gap in the drain pipe" is any different than just having the garbage disposal act as an air gap.

I'm also not sure I understand why it's bad to have the dishwasher drain line go through the basement. I mean, will there be that much less water sitting in it if I route it behind the cabinets? Presumably the water that's going to be sitting in there is the rinse water anyway.

Is my installation bad because it (1) goes into the basement or (2) because it hangs down so low, or (3) because it has several different kinds of pipe.

If (2) I could easily change it by installing a new hose that I attach to the joists in the basement so it's not hanging down so low. If (3) I could get a new hose long enough to make the full run. If (1) then it's considerably more work as I have to figure out how the hose can be routed through the cabinets and drill holes through the cabinets and such. I don't want to do that unless there's a good reason to go to all the trouble. (I'm supposed to finish this job in one day so we can use the kitchen again.)

How sharp of a bend can the drain hose make without causing trouble?



I'm a little confused by this. Right now the hose is under the floor, which appears to be considered part of the problem.


Do you know what the words "industry standards" means?


Do you think that massacre of a setup you have would pass in any state?



You've taken a mere simple situation, complicated it, over analyzed it to death when a plumber could of come in and made mince meat of that hack job.

This thread is certainly not useful to the attending audience by any means. It's merely portraying the short cuts your trying to get away with and the ones who are trying to help are TRYING to put you in the right direction.

Plain and simple, you're not cut out for the job.

adrianmariano
02-15-2007, 08:08 AM
Most of the discussion in this thread has been about air gaps, which I think probably has been useful to the audience. I feel like I have a pretty good understanding of the air gap now, though I'm a little puzzled by this "teed air gap" someone brought up recently which sounds to me like no air gap at all.

My house is over 50 years old. It's full of things that don't conform to current industry standards. That's life. I can't rip out the entire plumbing system and replace it with a modern one that conforms to industry standards, just like I can't make the basement stairs have a conformant rise and run. That's how it is with an old house. But this means that something beyond mindless conformance to modern standards is required. I need to understand how things work. (In my opinion the people who are not cut out for the job are the ones who undertake the work without understanding.)

So what specifically is wrong with my installation? It has a high loop which is code some places, as I understand it. Does code prohibit a dishwasher draining through the basement? Or it prohibits using multiple types of pipe? Obviously nobody would come in and install something that looks like what I have. But that doesn't necessarily mean that there's something wrong with it from a functional perspective.

It's often said: If it ain't broke, don't fix it. I'm trying to figure out if it's broken or not. (The dishwasher seems to drain OK, after all, and the drain line doesn't leak.) If it's not broken, my inclination is to follow the advise of the aphorism. It doesn't always make sense to replace legacy systems with new systems when the legacy system is working OK. I hadn't initially planned to do anything involving the dishwasher simply because it wasn't in the scope of the effort which was limited to stuff under the sink. I'm replacing the sink, not the dish washer. I'd be willing to bet that if I hired a plumber to come in and do the job for me that nothing about the dishwasher drainage would change.

That said, if there is a good reason and it's possible, I'll run the drain line through the back of the cabinet. But I don't want to do it just for the heck of it to make more work for myself and introduce more things that could go wrong. I don't think I have seen yet an explanation of why it would be better to run the drain line through the cabinet vs. putting in a new drain line that is fastened to the joists in the basement (and hence is a horizontal, rather than hanging down with the big dip). The drain line through the basement would be shorter and straighter. That's bad?

Verdeboy
02-15-2007, 09:10 AM
Is it up to code? No. Is it functional? Yes. There's an old saying, "Worst first." You probably have many other projects that require your attention more than this. If it ever starts leaking, it may be a good time to re-do the drain.

PS: Just don't expect a group of professional plumbers to give their blessing to a rigged system like that.

TedL
02-15-2007, 09:51 AM
As for safety, I believe the air gap at the dishwasher provides protction against cross connections.

I, like the originator of this thread, like to understand the reasons for things, so I can apply the principles in other situations and evaluate the need/urgency for corrective action. I realize this puts additional "work" on the pros who help out here, but I, for one, really appreciate it when it happens.

Example: In the city next to where I live, plastic piping is not allowed. Reason for the rule: A strong union influence.
What happens if plastic is used? Depends on whether the work will be inspected.

(BTW, the originator sounds like an IT systems analyst who is used to asking users "why" so that he can design a system to meet their actual needs, not just automate the currrent (often manual) processes. It's a good thing...really!)

adrianmariano
02-15-2007, 10:04 AM
I'm not asking for a blessing. I want to know what specifically is bad about it so I can decide whether it's important enough to do something about it when I redo the kitchen sink. Since I'll be disconnecting the hose at the disposal end this is a reasonable time to ask if I should do something about it. On the other hand, I'm not letting the project expand into a wholesale replumbing of the house. I know my existing dishwasher drain is not ideal, but just how wrong is it and what problems could it cause?

Specifically how is it not up to code? There appears to be a decrease in the size of the pipe when it goes from the white hose (5/8"?) to what looks like 1/2" copper. That would presumably be a violation as drain lines are not supposed to shrink. But is that it?

Gary Swart
02-15-2007, 12:02 PM
As I previously stated, I'm not sure what is technically wrong with running the drain hose under the floor, but the sag is bad and the splice is not good. What you probably can do to make this somewhat more acceptable is to replace the hose from the DW to the drain with automotive heater hose, probably 5/8", all in one piece. Fasten it to the joists so it runs in a straight with no dips. Also, if I read your photos correctly, there is a valve in the drain line. Get rid of that. Make sure the loop is as high as possible and attached to the underside of the counter in such a way that it will not kink. If it's any consolation, my DW supply line tee off the the main hot water line in the basement with a valve then a flex line runs through the floor to the washer. Not exactly textbook, but functional.

adrianmariano
02-15-2007, 12:28 PM
Also, if I read your photos correctly, there is a valve in the drain line.

It's not quite that bad, though the picture sort of makes it look like it. That valve is the for the dishwasher supply which sounds like it's run just about the same way as yours. There's a compression union and it goes down to thin flexible copper tubing and goes up through the floor. (Actually the compression union is covered with green crud which I think means it must be leaking a little, but not enough that I ever see it wet.)

Two questions about your suggestion:

1. Why is an automotive heater hose a better choice than a dishwasher drain hose?

2. Why 5/8"? Right now the second half of the drain line is 7/8". Isn't bigger better?

markts30
02-15-2007, 02:23 PM
Two questions about your suggestion:

1. Why is an automotive heater hose a better choice than a dishwasher drain hose?

2. Why 5/8"? Right now the second half of the drain line is 7/8". Isn't bigger better?

Don't know that automotive hose is better but might be easier to get...
Supply houses will have washer hose by the foot and you can buy the 10 or so feet you will need..

As far as the 5/8", might be he is referring to automotive hose ID (inner diameter) as opposed to the 7/8" OD washer hose (outer diameter)...

geniescience
02-15-2007, 04:18 PM
adrian

just a note to confirm -- you got your answer, which is that you could leave it for now and get around to it when it leaks if it ever does. But no individual will go on record as having recommended you do that. (No blessing asked for and none given.)

my point, which may not be relevant to you, was to get rid of the passage through the disposer by teeing into the kitchen sink drain above the disposer's Tee. Umm, is that original or not? I don't know, I really don't know. But if it is do-able, then it gets rid of the safety issues which a separate air gap will take care of.

David

TedL
02-15-2007, 05:08 PM
The smooth interior of the heater hose would provide less resistance than the corrugated DW hose.

Gary Swart
02-15-2007, 05:20 PM
My thought on the automotive hose was it comes in whatever length you need and since it is capable of handling hot water under pressure, it would certainly be OK for a DW drain which has no pressure. The size would depend on the size required by you DW and the tail piece at the drain and may or may not be 5/8". I was unaware the regular DW drain hose was available in long lengths, and that may be the way to go in order to properly fit the DW and tail piece. Don't get hung up on the automotive hose, get what will fit.

adrianmariano
02-16-2007, 05:50 AM
I have to admit that I was wondering if those corrugated dishwasher hoses were somehow smooth inside. Regarding dishwasher hose availability, I had noticed this mail order source which has 5/8" and 7/8" hoses available:

http://www.**************.com/dishwasherhose.html

But I hadn't looked at local suppliers to see if they are available there. (For all I know the above site is just selling automotive hoses as "dishwasher hoses")


just a note to confirm -- you got your answer, which is that you could leave it for now and get around to it when it leaks if it ever does. But no individual will go on record as having recommended you do that. (No blessing asked for and none given.)

Actually I'm still a little hazy about the answer to my basic question: why is my installation bad. Everyone seems to agree that it's terrible and needs to be changed, but nobody seems able to actually say specifically what is wrong with it. Are you saying that the answer is that it might leak due to all those extra splices?


my point, which may not be relevant to you, was to get rid of the passage through the disposer by teeing into the kitchen sink drain above the disposer's Tee. Umm, is that original or not? I don't know, I really don't know. But if it is do-able, then it gets rid of the safety issues which a separate air gap will take care of.

I don't think I understand this. Why is passage through the disposer bad? (Because the disposer might be full of crud?) So the idea is to tee into the other drain that doesn't have a disposer on it? Without a conventional air gap of some kind couldn't such an installation siphon water out of the sink back into the dishwasher?

Rancher
02-16-2007, 07:44 AM
Actually I'm still a little hazy about the answer to my basic question: why is my installation bad. Everyone seems to agree that it's terrible and needs to be changed, but nobody seems able to actually say specifically what is wrong with it. Are you saying that the answer is that it might leak due to all those extra splices? If you didn't think something was wrong with it in the first place, then why'd you ask? Personally I like it, I think you should leave it alone! Let's take a vote.

Rancher

Verdeboy
02-16-2007, 11:14 AM
Actually I'm still a little hazy about the answer to my basic question: why is my installation bad. Everyone seems to agree that it's terrible and needs to be changed, but nobody seems able to actually say specifically what is wrong with it. Are you saying that the answer is that it might leak due to all those extra splices?

IMHO, even if it never leaks, it's messy, sloppy, ugly, inefficient, and denotes poor workmanship.

adrianmariano
02-16-2007, 12:12 PM
If you didn't think something was wrong with it in the first place, then why'd you ask?

Verdeboy wrote:


IMHO, even if it never leaks, it's messy, sloppy, ugly, inefficient, and denotes poor workmanship.

So why'd I ask? What it really boils down to is that it looks bad. It's ugly, as Verdeboy says. Does that mean bad function? That's what I was trying to find out. I have, on the one hand, an inclination to change it for essentially aesthetic reasons and an opposing desire not to overcomplicate the job that I'm hoping to finish in one day. Understanding the functional concerns about the setup (if there are any) could tip me one way or the other on whether to change it or leave it.

geniescience
02-16-2007, 12:54 PM
adrian

i like your persevering attitude.

If I knew all the reasons why a multipart multimaterial hose were deemed bad, I might be already making a living as an exam-question writer for Master Plumber certification exams. Example: "List all seven reasons why ... is dangerous."

You asked "Are you saying that the answer is that it might leak due to all those extra splices? "

Can we agree that we both don't know for sure but that we both think that that is a sufficient reason -- all by itself -- to agree that the pipe could be deemed not up to snuff if it were for a new installation being prepared for a new buyer who would be expecting a clean and professional installation? I think so. Can we agree that "Code" is designed to produce that level of cleanliness and professionalism? I think so. Is there more? I don't know for sure, but I think we have studied this enough to wear out just about 99% of the population, if anyone is following this thread. Even the most dogged scientific researchers could ask why we want to know more.

If there were any other reason More serious, you would have heard it by now, I believe. Anyone can correct me if I have missed something important. I know for sure two things: 1.) it works for now, and 2.) you asked if consensus would be in favor of your changing it, and why.

Next subject. "Why is passage through the disposer bad? (Because the disposer might be full of crud?) So the idea is to tee into the other drain that doesn't have a disposer on it? Without a conventional air gap of some kind couldn't such an installation siphon water out of the sink back into the dishwasher?" -- Yes. Almost. Not quite. Close. The disposer may be full, and or it may do other bad things, and or the sink and or the dishwasher may also do bad things. Cross-connections and backflows possible everywhere. Rarely happens but can be fatal, lethal, deadly. It can be a matter of life or death. That is what plumbing is about. In my view, it is more complex than electricity which is also extremely dangerous.

Look at any installation with NO disposer, and then look at my remarks as saying "can we do the same thing WITH a disposer present, by just not going through the disposer?" I am not a plumber so I ask without knowing the answer.

Drinking water never kills anyone, until suddenly one day it kills people. Contamination. Sewer gases never kill anyone until suddenly they do. That's plumbing! (Sewer gases are sometimes odorless and lethal). A cross connection is never going to cause a problem until one day it just does. Suddenly one day it can really, practically, seriously and lethally cause a "public health problem". Although the probability is low, who will guarantee you that No one will ever sue you and that you will never feel guilty about your plumbing? As you are persistent, perfectionist and persevering, you may appreciate my telling you what I think may help.

Conclusion: air gap is a good thing. With no garbage disposer, it is easy to hide, in the drain.

David

adrianmariano
02-19-2007, 06:16 AM
The disposer may be full, and or it may do other bad things, and or the sink and or the dishwasher may also do bad things. Cross-connections and backflows possible everywhere. Rarely happens but can be fatal, lethal, deadly. It can be a matter of life or death. That is what plumbing is about. In my view, it is more complex than electricity which is also extremely dangerous.


The above is kind of vague. I thought the concern was water flowing backwards into the dishwasher, which is supposed to be a clean area. Also I guess it would be really annoying if the dishwasher filled up with water to the level of the sink from siphoning. Open the dishwasher and you'd have a huge mess.

What other cross connection of backflow is there in this situation to worry about? I can't contaminate my water supply because the faucet is higher than the sink. I guess I can contaminate the sink. But that's about it.

Other than clogging the pipes, what "bad things" can the disposer do?

What "bad things" can the dishwasher do? I could imagine it somehow draining water continuously. Or maybe draining water that is full of debris and clogs the pipes. But if the latter is going to happen you're presumably better off having it go through the disposer since the disposer gives you a second chance to deal with the debris.



Look at any installation with NO disposer, and then look at my remarks as saying "can we do the same thing WITH a disposer present, by just not going through the disposer?" I am not a plumber so I ask without knowing the answer.


As I understand it, there are two ways to construct an installation with no disposal. One involves a high loop air gap and the other one involves an air gap on the counter top. I don't see a reason why you couldn't have a disposer and nevertheless connect the dishwasher drain to the second sink drain which doesn't have the disposer. But you'd still have the high loop air gap or the air gap on the counter.

Now it seemed that you were suggesting some third type of air gap, a "teed air gap below the sink but above the trap". I don't understand what this is. And it seems like as soon as the water level in the system rises above it (e.g. into the sink) then water will be able to siphon back into the dishwasher (or water will be pouring out of this mysterious under-the-sink air gap). So this type of air gap wouldn't be as good as the other two kinds at preventing siphoning back into the dishwasher.

geniescience
02-19-2007, 06:42 AM
sorry I'm not able to describe things in fewer words, and more precisely too.
Not being a plumber, i'd better let someone else point out in a few words what i cannot. I realize that my explanation was far from clear.

Check out the analogy of the garden hose trickling water out, and with its nozzle in a puddle. Has been described many times before; it's a vivid picture.

About the air gap, I'll find that diagram I keep on mentioning, where there is no disposer. I'm sure you can find it too. The Tee is nothign special at all, it is the only way to tee into a drain.

bye for now.

david

geniescience
04-18-2007, 02:41 PM
.... can still have an air gap! If the sink's P trap is several inches below the sink, just Tee your dishwasher drain in under the sink, several inches above its P trap. That is enough air space to do the job. The air is in the 1 1/2" drain pipe above the P trap.

That is what I have. The "T" has a slight slope to it. It's copper or brass. From there, a rubber hose loops high (from the Tee) and then down to the dishwasher.....Adrian,
I found the thingie. It's called a Dishwasher Branch Tailpiece. Picture at this thread http://www.terrylove.com/forums/showthread.php?t=12532&highlight=dishwasher+branch+tailpiece

With it, you just high-loop to it; you don't put an air gap in the counter. Teeing in to the tailpiece like this eliminates the need for an air gap. The Tee itself IS an air gap.

david
edit (5:47 p.m.): why this was important was that I said I thought it was one way Not_To_Send_DW_Waste_Water_Through_ the_ Disposer. That may have been discussed in your other big thread.
2nd edit (36 hours later): a loop isn't higher than the flood rim of the sink so it isn't an air gap in plumbing terms. Under the right conditions it will let dirty water backflow into the DW.

TedL
04-18-2007, 05:50 PM
I don't see how the tee could be an air gap. In the situation where the drain clogs and wastewater backs up into the sink, you ahve a cross-connection between the sink drain and the dishwasher drain.

That having been said, there is an air gap between the waste connection at the bottom of the dishwasher and the fill inlet on the side or top of the dishwasher. So, cross connections are prevented.

Dunbar Plumbing
04-18-2007, 07:38 PM
geniescience,


Since you seem to be rewriting codes through personal opinion of what necessitates protection and what does not, explain to me what is the difference from your theory and that of a swimming pool full of water with a hose draped over the ledge and dropped to a lower elevation to create a siphoning effect.

High looping a dishwasher drain is a direct connection to the drain system.

Also, explain fluid dynamics and tell us how a larger mass of water can exert force on a small opening and produce enough pressure to elevate water to a higher elevation.


When you take your family out to eat this weekend, go back into the restaurant kitchen and observe the air gap that is installed on the dishtank; Then tell them you just hook it straight to the drain and watch the response from the health department.

dubldare
04-18-2007, 07:53 PM
... That having been said, there is an air gap between the waste connection at the bottom of the dishwasher and the fill inlet on the side or top of the dishwasher. So, cross connections are prevented.


One thing to remember is that the CLEAN dishes sit in the area below the water inlet's air gap. They can be fouled before there is an issue with the water supply.

geniescience
04-18-2007, 08:00 PM
i guess i'll have to edit that last post to say things more cautiously. That is clear to me.

Before I go back and re-read it and figure out what I could have said that would have been a little bit better, I'll ask that you just spend a few minutes helping me and everyone else with the right words that explain most of the problem. "Anything worth saying can be said in ten or twelve words." Please don't be sarcastic and cynical. I'm not a dolt; I can admit a mistake; I'm not usually far out in left field.

David

jadnashua
04-18-2007, 08:13 PM
As I understand it, an air gap is just that, a break in the connection. If water tries to go backwards, it ends up going out the air gap rather than through the dishwasher drain hose. Now, this can cause a mess, but it is safer than having it back up into the supposedly clean dishes and you not knowing about it. How often does this happen? All it takes is once.

TedL
04-19-2007, 04:37 AM
One thing to remember is that the CLEAN dishes sit in the area below the water inlet's air gap. They can be fouled before there is an issue with the water supply.

Absolutely. That's why I referred to "cross connections", and not "problems".

On the other hand, if I live in the house and the sink has backed up, and I go to unload the dishwasher and see/smell a pool of foul wastewater sitting in the bottom, I'm not going to just put the dishes in the closet or on the table.

At some point, rules can't protect people from their own stupidity/irresponsibility.