Interior Plumbing Kerfuffle

[kTHREE]

Not garage related, I have no where else to turn.
My dishwasher drains poorly and the cleaning ability is hindered by this (i'm pretty sure).
Now the spec of my dishwasher says 6' max when it comes to the drain line.
The current system uses 1/2" ribbed line all the way from the dishwasher to the garbage disposal/sink.
This run is about 10' in total. Here's a glorious drawing of the current setup:

My plan is to add a new 1 1/2" drain and vent line below the floor (open ceiling basement) so the dishwasher doesn't have to push 10' of water to the sink area.
While this is semi not to code(since may 2017 an above counter air gap is required...urh not happening), i think it is my best bet.
Here is a drawing of my planned idea:

AAV's are not legal in my state so that is out the window. There is no room for plumbing above the floor by the dishwasher so that's out as well. Is there a better way? I'd rather not loose headroom below since the basement will be finished soon so any idea's to mitigate using a vent below like I have planned?

 

[b-boy]

Wow - that's a weird setup. It seems strange to have the sink so far from the dishwasher. Any reason that it was done this way?

 

[kTHREE]

I have no idea. Was like that when we moved in.
It's also strange because there is an 1 1/2" hole under the dishwasher like there was a drain at some point? I've found many iffy oddities in this house so far so it wasn't a big surprise.

 

[flat350]

The new vent should be tied into the existing above the flood level of the sink.

 

[Jackfre]

One of your biggest problems currently is the use of the Corrugated plastic tubing. The resistance to the flow is enormous compared to a smooth walled pipe. Your proposed lay-out will work. You do not need 2" for that. These types of problems are the reason to not sheetrock a basement ceiling. You never know what you will need access to. Use a dropped ceiling.

 

[kTHREE]

Your proposed lay-out will work. You do not need 2" for that. These types of problems are the reason to not sheetrock a basement ceiling. You never know what you will need access to. Use a dropped ceiling.

Sorry I typed 2" instead of 1 1/2" for some reason.
The plan is to have a drop ceiling, but with the vent and allowing proper 1/4" for each foot for both I'm losing a good 8" of ceiling.

 

[kTHREE]

The new vent should be tied into the existing above the flood level of the sink.

Massive undertaking. Vent is through wall behind kitchen cabinets.

 

[tapered-pin]

The new vent should be tied into the existing above the flood level of the sink.

I'd tie the dishwasher into a waste line using the corrugated hose.

the waste line should have a studor vent at the top of it (several inches above where the DW waste line ties in) and just run that pvc line under the floor and tie into the waste line you plan on using in your diagram.

the DW drain line, studor vent riser, etc should all fit in a corner of your DW cavity in your cabinets.

similar to the way this DW waste line ties in (ignore the sink drainage and disposal)

 

[kTHREE]

Studor vent = AAV which is illegal in our state.

 

[GMCGarage]

One of your biggest problems currently is the use of the Corrugated plastic tubing. The resistance to the flow is enormous compared to a smooth walled pipe. Your proposed lay-out will work. You do not need 2" for that. These types of problems are the reason to not sheetrock a basement ceiling. You never know what you will need access to. Use a dropped ceiling.

Why not just try some 1/2" non corrugated tubing? Maybe 3/4" to resist and friction loss over the 10', would be cheapest first thing to try.

 

[kTHREE]

Why not just try some 1/2" non corrugated tubing? Maybe 3/4" to resist and friction loss over the 10', would be cheapest first thing to try.

I didn't know if that would even help/was a problem.

 

[fteufert]

Cut back on the pitch from a 1/4" per foot to say 1/8" per foot

Water will still run down hill.

My 100 year old house has a 1 inch drop from the tub drain to the stack, which is 12 feet away, and I never had a problem.

 

[joe--h]

allowing proper 1/4" for each foot for both I'm losing a good 8" of ceiling.

The DW drain is pumped out, there's no need for the drop.

But as said earlier, get rid of the flex pipe and you should be good.

Joe H

 

[Fixin'Stuff]

I didn't know if that would even help/was a problem.

The internal frictional losses are pretty high in that corrugated tubing. Something smooth on the inside will make for far less work for the pump in the dishwasher.

 

[klassenl]

And then make sure the little sump at the bottom of your dishwasher is clear of gunk as well

 

[The Cobbler]

I don't think the drain has anything to do with the performance of the cleaning , but it would easily contribute to poor pumping. get some 3/4" rubber hose and try that. think heater hose.

 

[Radix2]

Wait... your dishwasher is 10' from the sink....?

How do you do dishes, rinse...walk 10'..put in dishwasher...walk 10'...pick up dish, rinse...walk 10'...

Even if you are not a big rinser, you must need to get the last of the mashed taters and stuff off before putting them in? Empty the drink glasses, etc..

Is this god telling you to fix your kitchen layout?

inquiring minds want to know... and I would try running some 3/4 pex for the drain first.

And +1 on checking for a filter on the outlet, some have them and they gunk up easily...(esp if rinsing is hard to do?)

 

[doctordirt]

How about moving dishwasher next to sink?

 

[Richard Cranium]

Yes, if the dishwasher is not getting the dirty water out, then yes it will not get the dishes clean.
Use as small of drain as you can, and use 1/8 inch per foot, with the pump pushing it will work much better then what you have now.

 

[kTHREE]

Wait... your dishwasher is 10' from the sink....?
How do you do dishes, rinse...walk 10'..put in dishwasher...walk 10'...pick up dish, rinse...walk 10'...

Hose length is 10'
No idea, I picked up one of those wife things a few years back.

Is this god telling you to fix your kitchen layout?

Only if he's willing to front the cash.

How about moving dishwasher next to sink?

Nope.

Yes, if the dishwasher is not getting the dirty water out, then yes it will not get the dishes clean.
Use as small of drain as you can, and use 1/8 inch per foot, with the pump pushing it will work much better then what you have now.

Well if I can gravity to the drain, then i'm golden, this way the dishwasher only has to get to the drain and gravity takes care of the rest. Instead of it pushing 10' of water.

 

[Boomer343]

I would say that the way you are trying to do the drain with the 1 1/2 and the vent isn't going to pass a code inspection.

With that in mind I would either just wet vent it or put in an AAV using the 1 1/2 ABS.

 

[flat350]

Studor vent = AAV which is illegal in our state.

If an AAV vent isn't legal you can bet that tying a vent into the existing BELOW the flood level rim of the highest fixture on that vent will be illegal too.

 

[Muckin_Slusher]

Who cares what's legal? It's just plumbing.

If you want an AAV get an Oatey.

 

[tapered-pin]

Who cares what's legal? It's just plumbing.

If you want an AAV get an Oatey.

while I certainly agree with following the rules in most cases, you'd be a fool to think that plumbing systems, water, or physics is different in MN than it is elsewhere in the country.

AAVs are used all over the country, just because MN plumbers and pipe-fitters union has a stronger lobby and have worked to pass a law that effectively makes it unlawful to vent any way other than hiring a plumber to install a new stack is asinine..

 

[yeldogt]

My new house has a second sink that is more than 10' from the wall where the vent is -- I think this is a pipe size issue ... not a vent issue. I would run the the 1 1/2 drain w/o the vent... I'm not sure what it's getting you ... and not normally done that way.

 

[Milton Shaw]

Clean out the drain areas. Most of the sumps have filters or strainers that will clog with paper or other fibers. Also check the drain line, it must somewhere close to the dishwasher reach to the top of the dishwasher to prevent the water from siphoning out in operation. This happens as most dishwashers do not have any valves in the drain just the height of the drain hose loop to keep the water in the dishwasher during the wash cycle. This drain loop is very important especially if you run a drain line under the floor.

 

[dw1]

How old is this dishwasher? has it ever worked correctly the original way it was hooked up? might be time for a new dishwasher or at least a pump.

 

[Falcon67]

If there is a cabinet next to the DW, I'd run the 1 1/2" from there per your diagram and AAV it up close to the underside of the counter top. Do what will work. Amazon will send you an AAV in a plain brown box, nobody will know LOL. Otherwise find a way to stack up and out past the DW. Our old house had washer/dryer in the rear bedroom closet with the vent stack run up the outside of the wall on the exterior.

 

[tapered-pin]

I would run the the 1 1/2 drain w/o the vent...

drain will turn a Ptrap into a siphon without a vent.
without a P trap, you'll end up smelling the sewer every time you open the dishwasher (have fun eating off THOSE clean plates)

 

[yeldogt]

drain will turn a Ptrap into a siphon without a vent.
without a P trap, you'll end up smelling the sewer every time you open the dishwasher (have fun eating off THOSE clean plates)

So how come mine is OK and passed inspection? There are distance points to the vent stack based on the lateral size

 

[zeke67]

Another vote for an AAV. But, since you can't. The corrugated line off of the dishwasher needs to curl up to the bottom of the counter before anything else. Second, as mentioned in a few ways already, the vent line needs to be above the P trap, as high as you can make it. The way you have it drawn, if the drain line were to get plugged below your proposed vent line, then your waste water ends up flowing down your vent line. Not good for all sorts of reasons. Second, the P trap could get siphoned out, allowing sewer gasses in. None of this is ideal, but since your vertical run of vent line is separate from your vertical run of waste line it should work out.

 

[Nowater]

On the other hand, I just now fixed my dishwasher that was not draining properly, and not cleaning at all. I took close to fifteen minutes to remove the racks, lift out the screen and get to a piece of cabbage that was blocking the drain. Saved a service call.

Check You-tube for a video on cleaning your dishwasher.

No plumbing pipes, no PVC glue, no air admittance valve.

I needed a simple screwdriver and a tweezers to remove the food. I hope this works for you.

 

[yeldogt]

His current system is allowing much water to sit in the pipe -- typically there may be 18" of pipe before it starts to climb into the sink cabinet ... he has 10+ feet!

I just measured my laundry room -- the washer drain upright is 9' from the main pipe connection. Never an issue in 25 years.

 

[tapered-pin]

So how come mine is OK and passed inspection? There are distance points to the vent stack based on the lateral size

you may have a P trap downstream and not realize it (unless you built your house - which you may have done).

post pictures of your installation.

when I moved into my house (prior to my reconfiguration of the under sink drains), my DW emptied into a lateral that contained a horizontal S trap made of PVC pipe fittings. it looked bizarre, but it worked (vacuum break was provided by the sink drain and studor vent). I installed a proper receptacle for the DW when I changed sinks and added the disposal.