Smells like sewer?

[fiveshinds]

I need help; I have had this smell under my sink and sometimes in my master bathroom from the toilet area off and on for sometime now. The smell will be there sometimes and sometimes not (when it is there, it's obvious). The majority of the time, it will come from under the kitchen sink from the "air gap" or what I was told to put in that could suffice. I have tried to pour hot water, I've tried chemicals, and lemons and oranges, nothing seems to help. I have potpourri under the sink and while this method does help to mask the smell, it by no means fixes it!
Here's the skinny: The house was built in 2008, I bought it in July of this year and almost immediately went to Home Depot and bought what the sales associate recommended to go in place of the air gap that should go on top of the sink (as my sink has no hole for it). I don't know if the smell was there before I put in the "air gap" or not; the absence of an air gap was mentioned in the inspection so I wanted to remedy the "easy" stuff. Anyway, I have noticed a putrid smell coming from under the sink; it will sometimes smell for 2 or three days in a row, then nothing (noticeable) for several days, then "IT" will come back. I will post images of what I installed and of the p-trap and dishwasher hookups if forum allows.
Note: The smell was also noticed in the master bathroom about 1 month ago but that incident was isolated to that single time (not sure why or what was different).
Any feedback would be welcomed; I am at my wits-end! Even if your feedback recommends I call a licensed professional, that would be welcomed too.
Just noticed while trying to upload these pictures, is there a certain height above the drain the "air gap" must sit?
Pics:
http://www.plumbingforums.com/forum/members/fiveshinds/albums/under-sink/219-cimg6604.jpg

http://www.plumbingforums.com/forum/members/fiveshinds/albums/under-sink/218-cimg6606.jpg

Thank you in advance!

 

[Mr_David]

That is not an air gap.Did it smell before you put that in. That looks like an air admittance valve not normally needed unless you have a venting problem. That home was built in 2008, then there is most likely a vent in the wall going up to roof to let sewer gases to escape from sewer system.

 

[fiveshinds]

Thanks Mr. D; are you recommending I remove that valve after I make sure there is a vent in the roof? I didn't notice it before I put that valve in, however, I was only in the house for a few days to a week before I installed it.

 

[Draindit]

yup. One of the cheapy air admittance vents. possibly one of the mechanical ones with the spring in it. Those were built to fail it seems like. Are the threads on it sealed? They should be. And you are right, it is way too low. It should be installed as high up in the cabinet as you can get it. preferably higher than the flood rim of the strainer basket.

 

[fiveshinds]

Draindit - The threads are sealed, the pic doesn't show it, but they are. Any ides on what the risks are if I remove that valve all-together and see if the smell never comes back? The reason I put that valve in, is that I thought if I didn't have it, I risked the sewer backing up in the kitchen?
Any ideas guys?

 

[phishfood]

The air gap that the home inspector mentioned is most likely for the dishwasher. The air admittance valve that you installed does nothing to remedy the lack of an air gap on the dishwasher drain. Tie the dishwasher drain off as high as possible to the bottom of the countertop, remove the AAV, and all should be well. Under current code in my area, air gaps are not required if the dishwasher drain hose is routed as I mentioned.

 

[fiveshinds]

Thank you phish - as of now, The AAV has been removed and a cap has been installed; I will update in a week or so.
Thank you all for the rapid responses, help, and input!

 

[fiveshinds]

Phish - What do you mean by: "Tie the dishwasher drain off as high as possible to the bottom of the countertop"?

 

[phishfood]

Use a ziptie or something similar to attach the drain hose to something on the bottom of the countertop. If the kitchen sink has mounting clips, that is a good spot. If not, a VERY SHORT screw into the bottom of the countertop will give you an anchor point.

The reason for attaching the drain hose to the bottom of the countertop is to make sure that the drain hose empties completely from the high point down to the connection to the drainage pipe. This is to provide some protection against waste water/sewage backing up into the dishwasher if the sewer line were to clog up and back up into the kitchen sink drain.

The Home Depot employee steered you wrong. An air gap for a dishwasher drain will prevent the drain from getting into the dishwasher, the air admittance valve that you have pictured is intended to allow air into the drainage system to when the kitchen sink drains. It is likely sticking open, and allowing sewer gas back into your house. Two completely different things, and one can't be replaced with the other.

 

[fiveshinds]

Thank you again, phish, I will tackle that immediately!