Roof Vents and Odor

[BigBoy2U]

I recently have had a bad black tank smell in my bathroom. I replaced the toilet a couple months ago and replaced the O ring also. The smell started and is really bad when it hot out. If I use the fans to pull air out of the unit I can fill the rig with the smell of the black tank. So I thought I would get up on the roof and check the vent(s). The first one I suspected was the one near the bathroom. I removed the cover to find it full of wasps. Killed them and removed the nest. But the pipe was still blocked I was shocked as I was sure I just cured my problem. I removed insulation. Then the ABS pipe just slipped out and I realized it was just vented into the attic. So this must be the vent for the bathroom fan. I replaced it and put a nice fiberglass screen glued to the top of the pipe to keep bee's out. So then I check the next closest vent and it really has no smell so I figure it must be the gray tank vent. But then I notice that way over by the passenger front near the closet area is another vent. I go check it and its also has a nice big wasp nest in it. So I kill and remove that. Only to find insulation again. I remove the ABS pipe and it only goes into the attic? What is this pipe for?

I then check what I thought was the gray tank vent. It was clear. I took a hose and ran water down it and had water coming out of both the black and gray tanks. Is there only one vent for both tanks?

Short of the O ring slipping up the toilet on install (Concerto) what else can cause that black tank stink? I don't have the smell in the basement and it only seems to be in the bathroom. 2005- 36TK3

[sr]

I have had a smell as well and been chasing it for over a year tring to find out where it came from and finally narrowed it down to coming from the basement. I was able to close the entire trailer up and opened the sliding doors that go to the tanks and furnace etc. The smell was pretty heavy. I then went into the trailer and I determined the smell was getting into the trailer via the cold air return and the sliding door that goes between the bedroom and the kitchen. (It also acts as the cold air return). I called DRV and I am taking it to Interstate RV near Howe next week for them to fix the problem. What I think has happen is the vent pipe has come loose from the tanks and allowing the odor to escape into the basement and then into the unit. When I smelled the odor, I would turn on the exaust fan in the bathroom and that just made it worse. I have kept the doors open to the basement and the odor went away. That pretty much makes it coming from the tank area in the basement. I'll let you know what they find next week when I take it in.

[BigBoy2U]

OK thanks, I can't seem to smell it in the basement. I checked the cold air return and even with the fantastic fan on and I can feel air coming in from the basement (nothing beats that kind of dirty musty smell) I can not smell it. But if I leave the bathroom window closed and turn on the bathroom exhaust fan or the fantastic fan it stinks. But only in hot weather...LOL

I am pretty sure I need to pull the toilet and check the O ring. I just can't believe a poor seal at that point would make that much smell.

The odd part was when I was on the roof the roof vent had no odor at all. It was in the high 80's that day and the bathroom was stinking but the roof vent had no smell.

I even emptied the black tank thinking the pipe might have slipped down and still no smell.

On my last trailer the roof vent always smelled like a sewage plant.

[BobW]

Last year I took the bath fan out because it made noise. I found that the fan exhausted to nowhere. There was only insulation and nothing exhausted to the outside. I pulled some of the insulation out and discovered that there was a exit to the outside.
Also last week I noticed that the toilet rocked and there was water on the floor. I pulled the toilet out and found the seal was rotten. This toilet is only a year old.

[BigBoy2U]

Well I have heard about the exhaust fan not going to anywhere before. But what really bothers me is that I am a general contractor and the fact you have an open space that would have colder air in the winter and then blow hot air into it will create moisture. Even with the so called vent it will condense on a cold surface much like a cold glass of water does. I am lost as to why DRV would want to push warm air into the dead space above the ceiling. You are only asking for a lot of mold over time.

When I pulled the ABS vent out of the roof it was just stuffed into the insulation. I have been reluctant to clean out the bathroom fan for the reason listed above.

You never blow warm air from a heated space into a cold attic.

Still no one an any Suites Owners group seems to talk about the vent in the roof that is over the bedroom on the passenger side.

Anyone have an idea why this is located there? And what is it's purpose?

If it wasn't for the fact both vents that go into the attic where stuffed into the insulation I would have a trailer full of wasps and a huge nest. Just stuffing a pipe into the insulation and not putting any cover over it to prevent insects from getting in a totally irresponsible.

[sr]

Is there a way to attach the exhaust fan to the Vent? I would think that is how it should work?

[bstark]

I first posted on this issue way back in 05 I believe. My cure was to cut a plastic container that distilled water came in to fit as a duct which served to hold the fiberglass batting out of the way and also to direct the air from the fan staight to and only to that vent.

The other vent mentioned above the bedroom on the passenger side of the trailer may be the housing for the wind sensor for the automatic awning control ? ? ?

[BigBoy2U]

No the wind sensor is located on the passenger side near the front corner. This vent is on the drivers side in about the same area. It is installed just like the bathroom fan vent.


Typical construction methods dictate that when you have warm air enter a cold space like the attic area that warm air needs to direct vent to the roof vent and with an insulated hose to prevent condinsation from forming on the hose.

[bstark]

While RV manufacture's try to emulate most visible aspects of sticks and bricks amenities, that attic venting with it's condensarion concerns is just one aspect that gets ignored because it's not visible unless you had cause to go digging up there & discover it by accident.

Another item that may make you cringe is to take a close look down from the roof through the skylight over your shower and observe the method by which they have provided framing/trim between the inner and outer skylight with it's attendant condensation concerns.

Would it really cost that much more for Dometic to provide side wall vent covers that have some form of mesh screening on their inner sides to prevent wasps and other critters from entering our trailers via those large openings and ditto for those roof vents.? I could go on and on with this, but it has more to do with the buyer education and per-unit cost "out-the-door" for shareholder return.
.

[BobW]

Still no one an any Suites Owners group seems to talk about the vent in the roof that is over the bedroom on the passenger side.
Anyone have an idea why this is located there? And what is it's purpose?

I think it's there to vent the battery compartment. Not sure.

[sr]

Bruce, I removed my fan and sure enough the vent was above the insullation and the fan vented into the plenum. I removed the insullation around the vent. I then purchased some flexible 1 1/4" plastic hose and cut it to approximatly 10 inches and stuck it inside the plastic pvc pipe/vent. I then used your idea to put a plastic bottle the size of the fan opening and taped it to the fan. The mouth of the bottle fit exactly inside the flexible tubing. I then re-installed the fan, Turned it on and went to the roof and felt a good flow of air coming out. One problem I had was that the vent came down right above the air conditioner ducting. I had to smash the duct a little to get the hose inside the vent.There also is another vent that is about 3 feet away from the other vent. I took the top cap off and it also vents into the plenum above the insullation. I think I will call DRV and ask Kent how the vents are supposed to work and see what their thoughts are.

Thanks for the insight. My exhaust should be much better. Now that we have a better understanding how the venting works it will be curious to see if there is a condinsation issue going forward.

[retiredchuck]

:x I had a smell coming from the outside of the bathroom door and the door to the washer, on my 36ck3, Turn out to come from the drain pipe that you hook up your drain tube from your washer.It smelled awful,I pour some of that stuff for the gray tank.and it got better.Is this normal for oders to come from this pipe in the closet??

[bstark]

On my trailer with washer installed that hose is sealed around the top of that drain tower and the other part of that system is a springloaded vent valve that sloows air to enter the pipe to assist effecient drainage from the washer but not allow anything, including gases, to exit that vent.

If you do not have a washer installed in that drain pipe and are not using it, you could very easily plug it with some thing to prevent fumes. It is not required to be left open for venting purposes.

[BigBoy2U]

On the 36TK3 the W/D is located as a stacked unit next to the bathroom

[sr]

I think I found my problem. As Bruce stated there is a vent pipe for the washer behind the closet in the storage area. The vent was not screwed in very far. Just a couple of threads. When I took the cap off to check the seal the odor came out. Much the same smell as I was woking on. I screwed the cap as far as I could and closed all the doors. I will see if there is an odor in the morning. If there is no odor or if there is an odor, I will cap off that vent as I donot have a washer at this time. There could be a bad seal. This could be the problem in all the past post. I will keep all informed.

[RodeWorthy]

When I detect gray water odour in W/D closet it is an indication my tanks need emptying. I have tried placing a heavy plastic bag secured with a heavy duty elastic over the standpipe cap but it did not make any difference.

[RodeWorthy]

The roof vent on the front street side routes my solar cables from the battery compartment to the roof. Mine are custom but it may well be the standard #10 solar prep wire pair is coiled under there too.

[BigBoy2U]

But for those of us that use the W/D the P-trap is full of water and have no smell from the W/D area.

Anyone know what the vent on drivers front goes to yet? Its not for my W/D mine are not located in the front closet.

[sr]

I think I have my odor problem fixed. I closed up the trailer last night and opened the sliding doors in the storage area and no odors at all. So I will monitor the next few days and see how it goes. The air valve on the washer drain seemed to be the culprit.

[Diesel-Gypsy]

SR, I have the same vent in my little W/D room, I simply put a zip-lock baggie over that vent, and sealed the zip-lock baggie to the vent stack pipe with a HD elastic band.
No more evil-odors escaping there.

Rick

[Haggis]

I was on the roof checking the vents and tapped the top of the covers on all vents with the handle of a screw driver and only got a hollow sound from one of them. Took the covers off and three were stuffed with insultion.

I discussed the vents on the roof with the factory the last time I was there and was told there is only one vent and this services both black and gray tanks. The others with vents covers provide access and are stuffed with insulation until such times as when it will be needed for wiring such things as solar panels, satelite, etc.

[BigBoy2U]

Then what is the point is having a bathroom fan? And three pipes that fill with bees nests?

[RodeWorthy]

I was on the roof checking the vents ...

Me too. All this discussion had me curious. I concur with your results. Of the 4 vents on the roof, only one was plumbed to the tanks. Two are blocked off at the insulation and the one at the front street side allows access to custom solar wiring.

I did take a look at the bathroom fan. Wish I hadn't. Thought I might be able to resolve the fan venting. I made the mistake of disconnecting the fan at the connector and the wired portion of the connector promptly disappeared into the housing. That was fun to remedy. As far as venting the fan to the outside vent it did not seem practical to me. The nearest vent is directly over the HVAC duct and not accesible. The volume of air that could get out the vent would not be large. The fan does move a lot of air and it is going into the "attic". Of more concern to me was the total lack of insulation next to the curved cap of the roof. This no doubt runs the full length of the trailer but I was only able to observe it in the area of the fan. I put the fan back together and moved on.

No bees in the vents but dozens of yellowjackets around my tow vehicle next to the trailer. They love the mirrors and are setting up camp in the door cracks. They had the beginnings of a nest attached in there. Anybody know how to discourage these little tigers? I have been beating on them and they have nailed me twice. The war is on.

[BigBoy2U]

Think I am going to pull the power to the bathroom fan and seal it off. No reason to not just use the window. Last thing I want is mold.

I did glue fiberglass screen to the top of the other pipes after I cleaned out the bug infested insulation. Not sure I want three open holes into the attic area. I can see the snow building up around the vent, then melting or when you wash the roof water going down into the insulation and getting it wet.

I think it would be best seal the pipe and then to just cap them with an ABS cap.

[BobW]

I did take a look at the bathroom fan. Wish I hadn't. Thought I might be able to resolve the fan venting.

I just took some insulation from the fan to the vent away. The air should force it's way outside.

Of more concern to me was the total lack of insulation next to the curved cap of the roof.

I took my clearance out and noticed there was no insulation on the curved area of either the front or back. I think it vibrated down.

[Motor31]

You might want to rethink sealing the roof vents. No matter how good the seal in the ceiling there will still be moisture from normal living action gathering in there. That would be a perfect place for mold to develop. The venting will at least allow some drying action instead of pooling of moisture.

The insulation used in these rigs WILL settle. Since they use loose fiberglass insulation it will settle in the walls and in the attic area. The older and more miles the rigs get the more the insulation will settle. In the case of the walls it will leave gaps in the walls with no insulation. Gravity will assert it's influence over time since the fiber glass is loose and there is nothing but a minimal amount of glue on one surface of it.

[BigBoy2U]

Well DT sealed them with insulation. The insulation they stuffed into the bottom of each pipe was more than enough to stop air flow. But it does not prevent water going down, bees and other bugs looking for a nice warm place to live.

They were never installed as a means to ventilate the attic area. To correctly do it would require an open area above the insulation and a cross vent at the rear of the trailer. It still does not mean the air will flow. The cross members with insulation will prevent a cross flow.

You have to remember the construction of the unit. Its consists of: Vinyl Ceiling, Sound deedening foam, Luan, R-19, 1/2 plywood, felt, Roof Vinyl. There is NO moisture barrier.

So the introduction of cool air at night against a warm ceiling can create dew. Simply put this roof was designed to NOT be vented. So long as it remains dry it won't ever need to be vented.

Here is a link to everything you wanted to know about flat roof venting and it also states that in many cases venting vs. non-venting had no significant difference when the roof started out dry. Only did if have an effect if the roof was wet.

http://irc.nrc-cnrc.gc.ca/pubs/cbd/cbd176_e.html

[RodeWorthy]

There was no insulation stuffed into the ABS pipe in the "vents". There was glue on the bottom of the pipes and they were set on the existing insulation. I opened up a small hole in the insulation below the vent nearest the fan and some air can vent there but not the high volume at low pressure from the fan.

The insulation at the curvature of the roof did not slip down. It was just not there. This area is above the top cross member of the walls. Interesting that you, Bob, found the same condition near the clearance lights. If this condition exists around the entire trailer then there is a significant area with zero insulation.

I have flooded my roof with a garden hose and no indication of any leak around these covers. Even the front one where the dealer removed the ABS pipe. They are effective to keep water out. My rig has not seen signifcant snow and I intend to keep it that way.

Bees are another matter. Screen over the ABS insert should take care of that if the problem is severe.

[W5LEW]

I installed a new toilet a few months back and have a black tank smell now after flushing the toilet. I think I had the smell before I installed the new toilet, so I don't think the problem is the toilet. I installed a Siphon 360 Vent as someone in the group recommended earlier in the thread. (I'm wondering why the combination Black/Gray roof vent didn't have a waste smell up on the roof before I installed the new vent?) However, it has not helped very much (I had high hopes :-( ), so I'm wondering what to do next? Go the solar fan vent route or ?
Thanks for your help.

Lew in Texas
2008 DRV 36TK3

[Stripit]

Do you back flush the black tank, using a system like Flush King or use the built in black tank sprayer? In all the years we lived in the trailer as full time travelers we never had what your experiancing as an issue. The new toilet isn't loose to the floor and not sealed correctly? I always used Calgon once the tank was cleaned and used plenty of water always. Made it easy to flush clean.

[W5LEW]

Stacey, I have a built-in flush system in the black tank. I used it a few times at first and then it started some kind of leak around my garden hose in the water bay, so I stopped using it. Maybe the jets became clogged? I also use RV Digest It every week when I empty the black tank. It does a terrific job with its enzymes of breaking up the waste into liquid, but it recommends that you do not flush the tank each time so necessary bacteria will not be removed. We are stationary - not traveling at this time.
The toilet is not loose and it is tightly sealed to the black tank by a threaded extension. Maybe a thorough cleaning would help like you suggest.

Lew in Texas
2008 DRV 36TK3

[Stripit]

Since you are stationary have you got up on the roof and run the garden hose dow through the air stsck vent to ensure no bird nests have been built? Or even leaves that might have fallen into that stack and blocked air escaping? You can run water down that pipe as it will go directly into the black tank and clear that line should anything be stuck in there. I used to own the Flush King and back flushed the grey and black tank at least every month or sooner depending on how much time I wanted to expend.

[W5LEW]

Nope, I had read that someone did it. However, that ought to be the next thing I do. Thanks.

Lew in Texas
2008 DRV 36TK3

[Stripit]

I'm just trying to come up with what might be causing the problem. I found the start of a bird nest in my vent stack once. There was no cap on mine and things can get in there.

[W5LEW]

Update on my problem: I hosed down my combo black/gray water roof vent today and now can smell the black tank - success! The best news: I think the Siphon 360 Vent is working now that the black tank vent is fully open. Almost no smell at all - excellent! Thanks to Stacey for the reminder to do it. I remember shining my powerful flashlight down the vent tube and it looked clear from what I could see, but apparently there was some obstruction further down. The powerful, rushing water stream opened it back up.
I now can recommend the Siphon 360 Vent as a possible cure for RV bathroom smell.

Many thanks to all,

Lew in Texas
2008 DRV 36TK3

[Stripit]

Don't ya just love it when a suggestion actually works and you can say success!!

[W5LEW]

Don't ya just love it when a suggestion actually works and you can say success!!

Yep I do. Thanks again, Stacey.