Kitchen drainage question

[ovbg]

Hello, I am writing here despite being in Germany because my German is still not good enough for this, so I am hoping one of you guys can help.

My wife and I have bought a new build apartment (still under construction but only a couple of months away from being finished)

The question is regarding the lack of a slope in the kitchen sink/dishwasher drainage pipe. From the sink, the pipes drops to the floor level, where it has a 3.2foot (1meter) length, then a 90° turn, then another straight 18foot (5.5meter) length before it reaches the main pipe where it drops out of the apartment.

This length of pipe is flat on the floor with no gradient outside of the drop from the sink.

I have been told that this may be an issue with smell and run off. For smell, it was suggested to have a ventilator filter of some sort.

My question is, could this length really be a problem with runoff? The pipe is 2inches (5cm).

Regarding the ventilator (Air Admittance Valve, AAV), will this assist in smells and runoff in any way? I am guessing this device connects under the sink somehow.

Due to the type of building and the construction company, we have very limited choice in what we can do with this pipe. It can not go inside the support wall etc. If it needs a larger gradient, it would mean we would have to incur large costs on our kitchen installation which we don't really have the funds for any more, so I am hoping that that step is not needed.

Thanks in advance for your help :O)

 

[Chris]

If it is just a meter that is at 0% slope then you should be fine, I would worry if it was a longer section. Also your P-trap should stop the smell from coming through.

 

[LiQuId]

You have some issues here,

First The 90' on the bottom of the pipe is not Code ( 90's in drainage can go from horizontal to vertical but a vertical to horizontal run needs to be 2 45's... seems odd eh, the 45's offer better flow charactoristics, this is why )

and a 2 inch pipe's MINIMUM grade is 1/4 inch per foot, and It cannot Run longer than 8 Feet at that grade without having a vent installed as it drops below the diameter of the pipe.... You will have issues with the pipe backing up and clogging for sure.

An Air admitance valve ( cheater vent ) installed downstream of the trap would protect the trap and keep it primed( no smell ) but You still have an issue with the grade, Although It would now be a Vented pipe, It would still require proper grade...

The moderator Above has not properly read your post I figure and it would be an issue to run a 2" pipe at Zero Grade even if it were " just a meter " , Sorry Chris, but this is Plain bad advice.


There is always a way to make grade, If not then thats when you FIND one. You Dont do it half assed and hope for the best.

IF you are sure there is no other way, then I would suggest you replace the bottom 90 with a Wye and 45 and put a cleanout fitting on the end of the wye, get a Cable snake from the hardware store for 20 bucks and plan to use it .... I wouldnt ever do this, but its the best I can offer asside from just doing it right .

Hope this helps.

- Red seal Journeyman and B class gas ticket holder.

 

[phishfood]

Short and long sweep 90 fittings are allowed from vertical to horizontal in my state's code.

The AAV will provide a vent, though I do everything I can to keep from using them.

Every code that I am aware of requires 1/4" per foot of fall on 2" pipe. A little less than that will still work, but I wouldn't install it flat. Backups are quite likely to occur.

 

[LiQuId]

I too dislike the AAV, though it does save on Island Sink's installation time I would rather a proper Island vent.

Curious where you are from phish ?

 

[phishfood]

Florida. We use the International Plumbing Code.

 

[LiQuId]

Ahhhh, I am in canada... using the canadian code.

cheers for satisfying my curiosity

 

[ovbg]

Thanks all for your input, and LiQuId for the detailed info. Despite your excellent description, I am not 100% sure I understand it all. Plumbing is totally new to me. Could you explain again the 90', 45' bit?

 

[phishfood]

A 90 degree fitting, or a 90, turns the pipe 90 degrees, a 45 fitting turns the pipe 45 degrees. Two 45's put together will turn the pipe 90 degrees. but will make a more gradual turn than a 90 degree fitting.

 

[LiQuId]

when you go to the store Ask for a wye, a fitted 45, and a End Cleanout.

it will make perfect sense then.

The flat part of the Wye would be at the bottom ( on the floor in this case.... )
the Branch would be at the top ( the 45' part of the fitting ) With the Fitted 45 in it to accomodate the vertical pipe going to Your Sink
and the cleanout would go on one end of the run of the fitting ( when you can look through the Fitting its the run )

45 degree bends, and 90 degree bends are also Called 1/8th and 1/4 bends as a 45 will change the direction of flow 1/8th of a circle and the 90 will change the direction of flow 1/4 of a complete circle... it depends on where you live topographically.

Be again warned... You are going to have backups in the pipe if you dont get grade on it... you will NEED to Snake it often, which is why you would need to have cleanout access IF you were to run it like this.