SEWER SMELL WITH FANTASTIC FAN ON

[Larry-P]

I wrote about this problem in Feb 2012. It has returned.
Whenever we run the fantastic fan we get a sewer smell coming from the area where the vent pipe valve is located. On our model (2011 3455SA) we have the wrap around center island with the vent pipe valve located to the side of the sink area. When you open the cabinet doors along the sink that is where the smell is. Further investigation indicates that the smell is coming through the hole in the cabinet wall that the sink drain pipe & vent valve are located.

PLEASE NOTE THAT ALL TANK DUMP VALVES ARE CLOSED TO THE OUTSIDE.

I get no smell from our bathroom area or anywhere else. I have changed the vent valve twice. Both times I thought the problem was fixed only to have the smell return.
If I tape the vent valve closed to determine if the smell is coming from that pipe & I still get the sewer smell, what should I look for next?
Could Keystone builders forgot to cement a pipe connection? Our toilet black tank area is approx 10 to 12 feet away from our kitchen sink gray tank. Could the smell still be coming from the black tank area?
I'm at a total loss & I just want to puke when that smell comes in.
We are in desperate need of help.
Thanks.

[K0LCB]

Is it possible you had spillage in the underbelly?

[Larry-P]

No spillage

[rohrmann]

Does anyone know where the galley tank vent is on that model? The next worse smell on these things is the galley tank. Maybe you have a loose connection or bad vent coming off the galley tank. We have a problem occasionally, depending on which way the wind blows, when we have a ceiling vent open next to the black tank roof vent.

[Neil.M]

When we got our used 2007 2955RL we had terrible smells coming from the galley tank when running the fantastic fan. We added a cup of bleach in 1 gal. of water down the drain and after two drains the smell went away never to return. Odor is usually caused by bacteria growing and the bleach kills them dead.

[Irlpguy]

Larry-P I hope the following pictures and information may be of help to you. I took these pictures after my Satellite dish had been installed to see where the cables had been run. But I also had the smell in the Kitchen and because I had been in this area I knew what to look for.

Picture #1 - This is the picture of our storage area at the outside wall of the curved counter, it would appear to be the same as you describe.



Picture #2 - This picture shows the lower part of the cupboard that is nearest the entertainment center, the arrow was to show the dealer where there was an unrelated problem.



Picture #3 - This picture shows the back of my built in vacuum and the water lines to the kitchen sink. To the right of the water lines you will see the drain into the gray water tank below. That pipe extends up above the pipe coming into it from the sinks to a T, at the top of the T is a useless vent (my impression) and the other leg of the T goes over and up through the roof to an outside vent. This is not shown in the picture but I have pictures of that as well.



I first took the "useless" vent cap off (it screws off) and inspected it, it has a flapper and is supposed to allow air to enter in only one direction. It was not sealing and allowing the odor to come up from the holding tank. Since I had no cap to cap off that pipe I simply filled the vent cap with expanding insulation with the thought that I would eventually replace it. I have not replaced it and have not had the smell since. If you also have the vent to the roof from this same pipe then the "useless" vent is not needed at all, why it was put there is anyone's guess. You can check on your roof for the existence of this vent to the outside. If you do not have one then the other one will have to be replaced with hopefully a better quality one.

To access this area you must remove one small panel and the shelf in the cupboard next the entertainment center, there were perhaps 8 or 10 screws involved. Or if you don't have the built in vacuum you might be able to access it from that cupboard.

I hope this helps and with any luck you will have a vent to the great out of doors as there is on mine.

[Chip]

If you crack a window this should stop the suction when the fan is on. It just sucks the air right out of the gray tank through that vent Iripguy described.

I replaced mine the original was dirty and not sealing.

Works fine now but I will still crack a window when the fan is on high.

[rohrmann]

I realize the fix with the foam has stopped the smell, but the reason for the vent is also to allow the tank to drain without creating suction on the tank. It's like taking a soda bottle full of water and turning it upside down to drain, and the bottle will want to squeeze together because air can't replace the water. Same with your galley tank, needs the vent to keep the tank from distorting when you drain it.

[Irlpguy]

quote:Originally posted by rohrmann

I realize the fix with the foam has stopped the smell, but the reason for the vent is also to allow the tank to drain without creating suction on the tank. It's like taking a soda bottle full of water and turning it upside down to drain, and the bottle will want to squeeze together because air can't replace the water. Same with your galley tank, needs the vent to keep the tank from distorting when you drain it.

Actually on my 3402RL you do not need that AAV (air admittance valve) for anything. There is a proper vent going over and up the enclosure next to the wall from the counter, behind the power outlet and little cabinet in picture #1.
You do not need both, that was why I sealed it. All units may not have this outside vent on the kitchen sinks but mine fortunately did. If you look between the kitchen slide and the entertainment slide you will either see a vent coming out the roof or not, if you have one like mine does, then the other thing can be eliminated.

We had the smell even when the fantastic fan was not on, opening a window will allow the fan to draw air form the outside and not any vents but won't solve the real problem. Eliminating the AAV as I was able to do or replacing with a better quality one will solve the problem.

[rohrmann]

Ours must be the same, just haven't had the problem to have to expose the plumbing. Unless, like a lot of things on these rigs, the installer added the valve on yours but didn't need to. Glad you found the problem.

[vangoes]

On my 3455 I have a valve on the kitchen sink drain and another one on the bathroom sink. Both tanks also have an outside vent going through the roof. I had the sewer smell problem with my bathroom valve when the front A/C was on. I replaced the valve and so far things have been ok, but if it starts again I'm just going to put a plug in it. On another forum, someone stated that the reason for the valve and the outside vent is that the valve will prevent the water in the traps from being drawn out when the tanks are drained. That sounds reasonable to me because the outside vents will provide the ventilation to the tanks.

[billc1949]

quote:Originally posted by vangoes

On my 3455 I have a valve on the kitchen sink drain and another one on the bathroom sink. Both tanks also have an outside vent going through the roof. I had the sewer smell problem with my bathroom valve when the front A/C was on. I replaced the valve and so far things have been ok, but if it starts again I'm just going to put a plug in it. On another forum, someone stated that the reason for the valve and the outside vent is that the valve will prevent the water in the traps from being drawn out when the tanks are drained. That sounds reasonable to me because the outside vents will provide the ventilation to the tanks.

Vangoes, where is the valve located on the kitchen sink drain. I found the bathroom sink, however, the kitchen sink one has alluded me. Thanks.

[vangoes]

Bill, my unit is currently not at the house but I will double check the valve later. I hope I'm not thinking of my old SOB about the kitchen valve but I'm pretty sure that there is one! However, if I'm temporily brain dead, that could explain why only my bathroom valve has caused a problem !lol. Either way, in my old SOB I never had a problem with the valves releasing a fowl odor.

[Irlpguy]

quote:Originally posted by vangoes

On my 3455 I have a valve on the kitchen sink drain and another one on the bathroom sink. Both tanks also have an outside vent going through the roof. I had the sewer smell problem with my bathroom valve when the front A/C was on. I replaced the valve and so far things have been ok, but if it starts again I'm just going to put a plug in it. On another forum, someone stated that the reason for the valve and the outside vent is that the valve will prevent the water in the traps from being drawn out when the tanks are drained. That sounds reasonable to me because the outside vents will provide the ventilation to the tanks.

If your tanks are vented to the outside then a AAV valve is not needed, they are used where it is impractical or impossible to vent to the outside. When the tanks are drained on our RV's any vent prevents the water in traps from being drawn out and they also speed up the waters drain and prevent gurgling.

I do not have one in my bathroom, it is vented to the outside and so is my black water tank. I have no idea why the one was put in the kitchen sink drain. I am sure there are better quality AAD's on the market and I would have looked at one of those if I had not been able to eliminate mine.

With all the different floor plans and different locations of the placement of sinks it becomes impossible to always vent to the outside. They just do not need to use both.

[Larry-P]

Irlpguy,

I did as you suggested and plugged the vent cap under the sink after determining that there is an outside vent to the kitchen area. The problem seems to be corrected. I have the Fantastic fan on high with no windows open to get maximum suction from the kitchen area & wa-la. No smell.
Thank you so much for the information. Your a friend for life.
Larry-P

[Irlpguy]

I am truly glad that worked out Larry, happy trails.