Dishwasher Drain rough-in

**pilot4net2** · 03-06-2005, 03:51 PM

I am plumbing a dishwasher that will be in an island cabinet opening but the sink will not be by the dishwasher. Can I just hook the dishwasher hose to a 1 1/2" drain pipe plumbed with a sanitary wye and out of the top of the sanitary wye, install a AAV to serve the purpose of a vent? I really have no other way to drain or vent this fixture, so I hope my idea will work. Anyone's suggestions or ideas will be appreciated. Thanks.

**master plumber mark** · 03-06-2005, 04:07 PM

even though this is an isalnd install why dont you just a run normal radaitor 7-8th hose back to the garbage disposal through the crawl space?? You could evern run a 1/2 copper hard or soft line back to the disposal too.

hook it up solid or soft, either way it will work forever..

It can pump quite a ways., though I doubt you are going very far.

wether you would install an air gap or not is up to where you live.

,

**pilot4net2** · 03-07-2005, 12:48 AM

What I had planned on doing was coming through the floor with the drain pipe, putting a sanitary wye on top, come off the side of the wye and reduce down to the appropriate size barb fitting for the dishwasher hose. I then would put the AAV or Studor Vent/Valve at the top of the wye at the highest point possible inside the cabinet. Would this plan not work? If I do as Master Mark has suggested I would either have to go down through the floor, under the home, come back through the floor under the sink, and then tie it in to the sink drain at either the disposer or sink drain itself. I was worried about the resulting head pressure of this approach. The other way would take me all the way around the cabinet layout which would be about 50-60' of run to the sink. Once again, I didn't know if the pump on the dishwasher could handle that. I saw my idea in some variation working in some homes. The only difference was that the sink was right next to the dishwasher on the island. The sink was plumbed with the p-traps and the dishwasher discharges through a fitting on the drain for the sink. The sink drain would then exit through a pipe coming through the floor with the wye that I mentioned and the AAV or Studor Vent on top of the wye. The people in the home have been there for 3 years and have had no problems. I just don't want one to arise in this home. Any suggestions, ideas, or help that anyone can furnish will be greatly appreciated. Thanks.

**master plumber mark** · 03-07-2005, 04:05 AM

I have literally run hundreds dishwasher like this. 5 to 15 feet away and never a complaint. I have seen it over and over.
very simple , very easy.

Its really not a problem, and you have an outlet on the disposal for the discharge which is why it is there. totally legal.

these units will literally pump quite a ways away from themselves , you are not putting any more head on it, you are not pumping it up to the second floor, so it works perfectly fine that way.

you just drill a hole in the floor under the dishwasher, leave the loop in the line that is attached to the dishwasher on the side of it .

then just drill a hole under the kitchen sink, either you can run it out of 1/2 hard copper, ( I have seen this countless times ) or I myself have run 7-8 raradiator hose up to the flood rim (under the sink) hang it there with a clamp or hanger , and back down to the disposal... connect it to the dishwasher line with a couple of clamps and a piece of hard copper "connecter " inserted deep into the radiatior hose and deep into the dishwaher hose with a clamp tightened down on both.,, and you are good to go.

an interesting side note...

this same radiator ss hose clamp technology is already commonley used in all commercial jet planes ---ect ---think of that the next time you are flying at 35,000 feet in a thunder storm...

If its good enough for a jet plane, with lives on the line, its good enough for grandmas new dishwasher.

But if you do decide to make a project out of this , and run a drain to this dishwasher, a mistake I made one time was to take the high drain loop off the side of the dishwasher and run that down to a drain. DO NOT DO THAT. Some brands out there need that high loop left tied on to the unit or it simply wont fill up the unit peoperly, it just pours down the drain.

its the same with a washing machine. it depends on the brand.

good luck to you whatever you decide to do..