No Vent on black water tank

[Toolvault]

Hello All, I am just curious if anyone else has experienced this? I have a 2001 Cardinal 5th wheel. We purchased the trailer used about 5 years ago. We leave it in the camp space that we own and stay there a couple times a month in the summer. When we arrive at the trailer and use the toilet for the first time the tank actually seems to have pressure in it. It makes a noise when you flush it and you can hear air rushing out of the tank into the bathroom and it stinks really bad. A horrific smell. I put chemicals in every time we leave and the park pumps it for me regularly. I checked the vents on the roof by running water from a garden hose into all the vents. It only changed the water levels in my two grey tanks so it appears I don’t have a vent on the black tank. This is the reason the tank builds up pressure in the summer when things warm up. I pulled panels off that cover my tank and there is no sign of a vent. Has anyone ever heard of this. Did they simply forget to install one or are they not vented and this is normal and I needed to do a better job on flushing our tank?

[Bama Rambler]

It would be odd but you could have a "wet vent". Where the vent is tee'd into the toilet stack. Can you see the stack with the underbelly cover pulled off? If so can you tell if there's a branch off it?

At any rate, wherever it's vented, it appears to be plugged.

[Toolvault]

There are no tees off of the 3” line going from the toilet to tank. And I have 3 vents on my roof. 1 for the shower and 1 for the bathroom sink and the other for the kitchen sink. I’m able to see all the grey water vents and they do not vent the black water tank. I am a 100% that there are no other pipes coming off the black water tank. I was just curious if Cardinal had made the mistake of not installing the vent on anyone else’s. I have a good clear path from the tank to the roof through our linen closet. I plan on adding the vent.

[SeaDog]

something to consider is if you can T into one of the other vents you will limit the roof openings that can leak. Just a thought

[nomad297]

Your black tank vent is probably tied into the vertical portion of one of the other vents. This is not a wet vent as Bama Rambler has stated, but the incorrect terminology really doesn’t matter, and I will explain what a wet vent is if you like, but it would not pertain to this anyways. Since the black vent is tied into a vertical portion of another vent, any water you pour down the vent it is tied-in to will drop straight down, past the tee where the black vent ties in and it will flow to the tank which that vent serves.

You say that you have your black tank pumped regularly. With this in mind, if you didn’t have a vent on your tank, the tank would have collapsed the first time it was pumped-out and you would have much more serious problems than what you have described.

Your black tank is vented. No doubt about it. As far as the pressure build-up problem you describe goes, I don’t know what to tell you without actually being there and seeing what is going on. But I can tell you, if I was experiencing something like this, I would start the troubleshooting by slowly filling my blackwater tank with my black water flush system to verify there is some sort of blockage allowing air to enter the tank from a vent, but keeping it from exiting.

Bruce

[Wolf26]

Your tank is more than likely vented as stated above. If it was not vented, you would have problems dumping your tank, it would vacuum lock. You can't drain the contents without allowing air to enter the tank somewhere.

[nomad297]

Originally Posted by Toolvault

Hello All, I am just curious if anyone else has experienced this? I have a 2001 Cardinal 5th wheel. We purchased the trailer used about 5 years ago. We leave it in the camp space that we own and stay there a couple times a month in the summer. When we arrive at the trailer and use the toilet for the first time the tank actually seems to have pressure in it. It makes a noise when you flush it and you can hear air rushing out of the tank into the bathroom and it stinks really bad. A horrific smell. I put chemicals in every time we leave and the park pumps it for me regularly. I checked the vents on the roof by running water from a garden hose into all the vents. It only changed the water levels in my two grey tanks so it appears I don’t have a vent on the black tank. This is the reason the tank builds up pressure in the summer when things warm up. I pulled panels off that cover my tank and there is no sign of a vent. Has anyone ever heard of this. Did they simply forget to install one or are they not vented and this is normal and I needed to do a better job on flushing our tank?

Interested in knowing if you have done any further investigating or if you have resolved this problem. Do you have any good news?

Bruce