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Old 06-29-2015, 05:22 PM   #1
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Sewer smell

I had a Fan-Tastic-Vent installed in the bedroom of my Sandpiper SAF360DPEK. It worked great but recently I started getting a strong sewer smell when the vent is sucking the air out of the RV. It doesn't do it when it is pulling air in. There seems to be no problem in the bathroom and I've checked for a smell coming from the toilet, sink and shower = nothing nor does the bathroom smell. There also seems to be nothing coming from the heating vents or the washer / dryer connections which I don't use. Any ideas??? Thanks, Randy

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Old 06-29-2015, 05:49 PM   #2
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When you "flush" the toilet and the fan is on draw it will pull sewer fumes from black tank.
Yes I know this fan is in the bedroom but the fan has to draw air in from somewhere.
That's one possibility.

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Old 06-29-2015, 05:53 PM   #3
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Are any of the dump valves open?

Are you using any type of treatment in the tank?

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Old 06-29-2015, 06:38 PM   #4
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Do you have a black tank flush system that was installed by the factory? Those systems use a vacuum beaker or a "burp valve" to release air pressure while using the flush. I found a lot of Forest River trailers mount the vacuum breaker in the bathroom. Sometimes behind the shower stall or under the sink. Could even be in the wall but there is usually some kind of access panel to get to it. If you trace the water line from the back of the flush hose hook up you can usually find the area wear the valve is located. I've found that you can get a funky smell from them if they get stuck open. Sometimes they can still emit an odor even when there is not problem. Using the fantastic fan will pull the odor right out of the tank into your bathroom through the valve. I would suggest using an odor treatment in your tank anyway. If you do find you have a vacuum breaker and the odor is coming from it, I would replace it. They are fairly cheap and easy to replace. No special tools needed. Plus if it is stuck open or cracked it might be leaking water when you flush the tank.
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Old 06-29-2015, 06:49 PM   #5
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By chance do you have a Dometic 300 toilet? There is an issue with it collecting waste fluids inside the back of the toilet. The smell eventually gets strong, and any air movement spreads the smell. Do a search on here for Dometic 300 Toilet for more posts on this issue, if you do have this model of toilet.
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Old 06-29-2015, 06:59 PM   #6
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I would echo Ford Idaho, if I leave a dump valve open, I soon find sewer odors are coming up through the vent tube and spreading across the roof. You can even smell the odor by just walking around your RV outside. Any open roof vent invites them in, the Fantastic Fan brings them running. Just one possibility.
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Old 06-29-2015, 07:00 PM   #7
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A couple of weeks ago I drained both black and gray tanks in the evening. Got up the next morning and all was well. Opened up the bedroom fantastic fan vent and we went out for a few hours. When we came back the new trailer smell that we have enjoyed was gone and a nasty wet stinky old sock smell greeted us.

We checked everything from laundry basket to all drain traps making sure there was water in them.
Finally realized the gray tank valve had been left open from the night before but there was no smell in the morning until I had opened up the bedroom fantastic vent and the sewer gas came from the tank vent on roof into the trailer through the fan vent.
Not sure if this is what is happening to you but after having all windows open and gray tank valve closed the nice new trailer smell is back once again.
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Old 07-03-2015, 03:17 PM   #8
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Okay, sorry for the delay in giving you all some feedback but I finally got after it today. I was doing or, wasn't doing, what most of you suspected the issue was so I decided to follow OneRoomShed's advice and try and find the vacuum beaker or burp valve he was talking about as I do have a black tank flush. No luck inside so I ended up crawling in behind the control panel. I should have mentioned that I am very new at this RV living so I really wasn't sure what I was looking for but once in there I found 4 hoses which look like those you find on your dryer in the house. I presume this has something to do with the venting? Anyway, one was totally dislodged. I strongly suspect this is the issue as I started having a problem after going over some very rough roads here in the Great White North. The 5th wheel took a real beating so much so that it that the outside sink sewer line was cracked or broke in 2 places. Its 80 degrees here today so I have the a/c going. I will find out tonight if the problem is fixed but I'd be surprised if it is not. Thanks much everyone.
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Old 07-03-2015, 04:31 PM   #9
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Just wondering if the hoses you are talking about being like on a dryer are the soft aluminum foil type vent hose. Sorry I don't know the proper name. The only thing I can say is the black tank main vent uses pvc or abs plastic pipe. Those could be heating ducts. Also the vacuum breaker would be on the water lines. Usually on blue or clear pex water line. If you Google RV vacuum breaker for black tank flush you will find many pics of these. Usually it either clear or black. Sorry I can't give you better direction to go and find it but I will say follow the water line out the back of the black tank flush hose hook up . It usually goes up through the floor into the wall. You should see two water lines at this location because one goes up to the vacuum breaker and the other goes right back down directly to the black tank. It can be a pain to find it but it should be there. I still suspect the bathroom. Look for any removable panels in or around the bathroom. Your shower stall may have an access. Sometime it looks like a 8" round dial. It's usually just below the shower faucet. Turn it to remove it. If you see 4 water lines inside its probably in there. If not, look for removable panels in the cabinets too. Look at all the walls around the bathroom too. You may have an access from outside the bathroom. Sorry if I'm sending you on a wild goose chase but I suspect that its got to be there. Hope this helps you some, but if not I will see if I can think of anything else. One other thing. I read another reply about a Dometic 300 toilet ( think that was the mod number). He's right about this model holding fluids and sometimes solids. There is a sticker at the base of the toilet by the floor that should have the make, model and serial numbers. Check and see if you have this model. It could be the problem. I've replaced about 20 of these because of odor issues.
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Old 07-04-2015, 05:39 PM   #10
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Yes, that is what I'm talking about the "soft aluminum foil type vent hose" and it has clearly fixed my problem so I am not going to look any further. However I am going to save your advice on the vacuum breaker should I have any issues in the future. And, my toilet is the Dometic 310 - it doesn't appear to be the issue.

Thanks again!

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