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Dishwasher drain

Posted by mjsparky363 (My Page) on
Fri, Feb 4, 11 at 7:00

Good morning all. I've searched and read but still have a question about dw drain. I'm going to redo the kitchen and dw is not, and cannot be near the sink. My current dw (circa 1984 GE GSD model is drained directly to the main drain in the basement. The hose is looped up the back of dw and clamped to a 3/4 copper stub about 12" thru the floor to an 1 1/2" copper drain which goes directly in to the main. We have never had a problem with the water siphoning out or sewer gas or unclean dishes. Is it possible that this hook-up worked because this dw has a seperate drain solenoid where it looks like newer models do not? Thanks for any feedback and....!!


Follow-Up Postings:

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RE: Dishwasher drain

"My current dw (circa 1984 GE GSD model is drained directly to the main drain in the basement. The hose is looped up the back of dw and clamped to a 3/4 copper stub about 12" thru the floor to an 1 1/2" copper drain which goes directly in to the main."

This sounds wrong in many ways.


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RE: Dishwasher drain

Sounds wrong but has worked fine for 25 years using it twice a week. The question, is it because this model uses a dedicated drain solenoid and newer cost savings now just switch the pump on and off?


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RE: Dishwasher drain

A standpipe is one way to plumb DW. It's often overlooked when people describe plumbing options. A standpipe is one way to ensure there is an air break.

An air gap is another way.

A hose, looped high ("high loop") and going down into the basement is a perfect siphon hose, if it has enough water in it to get suction started. Therefore it is dangerous to assume that a high loop, without an air break, will "work" right when it causes drain water to travel downhill to the basement. The fact that it did work right in your case is not a guarantee, which apparently you know as your questioning implies.

The right question is whether, for any reason at all, unnecessary to get into, a new DW will not work using that drain configuration that you now have.

It's the wrong question to ask whether or not it's "... because this model uses a dedicated drain solenoid and newer cost savings now just switch the pump on and off? " If you happen to have hit the nail on the head, and if an experienced DW repair person or two read this and post to confirm this, then you will have gotten both the answer you needed and a lot of details, that may not be the essential details.

The configuration you now have is not an approved drain. I will bet it will not work. An air break is needed, if the drain goes downhill as far as the floor below. (Some dishwashers have a sentence in their manual about air gaps and drains going through the floor.) I think that those who know the plumbing code will post that code prohibits connecting to any P trap except one on the same floor level and in the same room.

"Sounds wrong but has been working..." It is wrong, but it has been working. Figure on changing this one day.

Hth


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RE: Dishwasher drain

"Sounds wrong but has worked fine for 25 years using it twice a week. "

That is beside the point.

What you have described is not accepted under any of the codes.


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RE: Dishwasher drain

There were dishwashers in the past that did not need an air gap or high loop due to having an drain valve that actively opened and closed/sealed via solenoid. For example, older KitchenAid units with non-reversing motors. My family had a 1975 KitchenAid added to a house that didn't originally have a dishwasher. It was installed at one end of a U-shaped kitchen that had the sink at middle of the U, drain line was 1/2" copper tubing that ran from under the dishwasher, along the cabinetry base to the sink drain, no high loop. It worked perfectly fine that way for many years. I've wondered what the folks who bought the house did when they had to replace it with a unit that couldn't work with that configuration.


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RE: Dishwasher drain

What most homeowners fail to understand is that the plumbing code is not a mechanical code, it is a health code. The rules defining drain connections are to insure that there will be no cross contamination from the drains to the potable water system or any clothes washing, dishwashing or food handling appliances.

Regardless of how you connect your dishwasher, if you fail to install the required high loop and air gap there is a potential that if the drain line should happen to get stopped up downstream from the sink the water discharging from the sink could get syphoned back into the dishwasher, especially if you are trying to open that drain line by using a plunger in the sink.

Now you may think you are smarter than those idiots that write the codes and you have an easier method of connecting it all together, but don't blame the plumber or dishwasher manufacturer if you end up getting dysentary from your dishes.

It is simply too easy to do it right the first time.


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RE: Dishwasher drain

I know the new dw will not work ,and I'm not ,by any means smart. I just was wondering why this setup worked, was it because of the drain solenoid. I wish I could find the old install book...


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RE: Dishwasher drain

"There were dishwashers in the past that did not need an air gap or high loop due to having an drain valve that actively opened and closed/sealed via solenoid."

None of the plumbing codes have ever recognized this.

It is the plumbing code that sets the rules.


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R2E: Dishwasher drain

it is true that public health is what is protected by the Code. You (or anyone) could cause death downstream of your plumbing. Other people's. Installing to code is a good idea. In my post above I did not mention this.

I wonder why manufacturers are not penalized when they mislead the public. I know of one high end manufacturer whose dishwashers apparently "don't need an air gap" because the Manual has an artfully worded sentence that says something about its preinstalled loop and check valve and also dodges the real subject too. It bothers me that hundreds of sharp and unscrupulous salespeople use this sentence to claim that this company's dishwashers Don't NEed An Air Gap Because They Have Already Taken Care Of It In The Machine, and they encourage buyers to show the manual to the local inspector who isn't ever the sharpest card in the deck, and the buyer gets his variance since the company's product manual "told" the inspector that an air gap was not needed. Secondly, I saw a sentence in another manufacturer's documentation about what to do if the dishwasher hose were to be connected to a basement drain.

Hth


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RE: Dishwasher drain

"show the manual to the local inspector who isn't ever the sharpest card in the deck,"

That may be the case where you live, but I can assure you, where I live nothing could be further from the truth.

For the most part our inspectors are nice guys who more often than not allow you a little wiggle room in the code, providing of course that you are being civil with them, but rest assured, they don't miss a thing.

In our jurisdiction the plumbing inspectors are fully sworn officers of the court and although I only know one who routinely does, they are all authorized to wear a badge and carry both handcuffs and a sidearm and they have full arrest powers.

In addition, while a mechanical or electrical inspector may issue a "Stop order" or even have the local utility disconnect the power until a problem is corrected, the plumbing inspector can not only issue a "stop order", and direct the municipal water supplier to disconnect the service, he/she can also issue an order to "immediately vacate the structure" and in a worst case scenario they may issue an "order of condemnation".

The Plumbing code is also the only code that is punishable by both civil (fines) and criminal (jail time) penalties.

I can assure your from personal experience that if you were to show the owners manual to an inspector in my jurisdiction they would say, that is fine for your machine, but the plumbing is an integral part of the structure with an anticipated lifespan of 100+ years whereas your dishwasher has an anticipated life span of 8 to 15 years and we can not guarantee the replacement machine will have those features, so you must install your drain to the code.


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RE: Dishwasher drain

Some DWs actually do have an integral air gap on the discharge side, and ALL of them have a gap on the input side.

The problem with things like a solenoid system is that it WILL eventually fail to close completely and thus not function.

Air gaps work.
The biggest complaint is the 'extra hole' and the cover beside the sink.

There are other ways of installing them though.


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RE: Dishwasher drain

If you're going to redo your kitchen and can not come up with a design that can have the DW next to the sink, then you have a poor design. You should engage the services of a Kitchen Designer and/or post on the Kitchen Forum for some assistance in achieving this minimal level of required functionality.


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RE: Dishwasher drain

Yes live wire oak I am redoing my kitchen. It is a 100 year old place and there is no way to get the dw next to the sink, due to size, existing main plumbing and existing structual conditions. I used to work in a resturant and my kitchen currently has more than a "minimal level of required funtionality". Why is it that a dw has to be next to a sink base. I have been in many homes because of my current trade and the dw is not always right next to the sink. In my case the layout requires a u shape, so the dw has to be "around the cornor" of the u.


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RE: Dishwasher drain

you are right mjsparky363 and you have made it clear that you have enough experience to know you are right. I'm glad you were able to defend yourself.

live_wire_oak has a mental model, and she won't let it go.

mjsparky363, venting (in plumbing terms) is one thing missing in the description you wrote in your OP. ("... looped up the back of dw and clamped to a 3/4 copper stub about 12" thru the floor to an 1 1/2" copper drain which goes directly in to the main...."). Are you willing to learn about venting in terms of plumbing? Search "DWV venting" and you will see it's a big subject, that many people have a hard time with.

A vent has to be in the picture, with your drain. A vent is in every picture, with all drains.

Since your DW is across from the kitchen sink, perhaps you could use a second vent installed on that side of the kitchen. Then you could have a separate P trap for the DW, placed somewhere between the DW and the vent. With a vent over near the DW, yu would have the right to position your DW P trap at the height you want (e.g. down under the cabinets and where you want (e.g. in the corner where it won't bother any of your storage). There Are physical limits to distances, so don't run with this until you double check with someone who knows DWV. Post here and see what feedback you get.

P.S. With a vent on the other side of the kitchen, you could also have a little sink over there. Could be practical.


Hth


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RE: Dishwasher drain

Thanks davidrol. The location of the dw is only 5' +/- from a properly vented sink. As I install the new cabinets I will run the drain under the EZR36 base over to the sink and tie it in to the tail piece or garbage disposal if I add one. In my area I don't need a AAV, only a loop at the sink base because of the proximity of the vented sink. My OP, probably not clear enough, was just for info as things that work but shouldn't, intrigue me. As this dw was here when I bought the house and it worked I never questioned it. It was only as I began drawing up the plans that I realized where the dw drained, knowing that it wasn't right, but wondering why it worked, hence the OP. Thanks again.


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R7E: Dishwasher drain

a.f.a.i.k.
DW's perform best if their hose loops high closest to the DW and not closest to the sink, when separated by a distance of several feet or more.

I would drill a hole along the top corner of the 36" cabinet and run the hose along the back corner / back top, under the counter. Then when the hose is inside the kitchen sink cabinet, let it drop down there to the connection ( Wye or Tee under sink drain tailpiece, or disposer connection ).

When the high side of the hose's circuit (or "loop") is close to the DW, the pump has to pump gray water up to the high point WHICH IS CLOSE and it therefore has less work to do and leaves less standing water in the drain hose. Standing water in the drain hose has to be pushed out each time the pump pumps, and this is inertia to fight against: makes sense to me, to minimize this inertia instead of maximizing it.

Hth


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RE: Dishwasher drain

Thanks for the info. In a way I like that better as, with a little contorting, I would be able to see a problem/clog in the hose.


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