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AC on - flush toilet - smells brought in ?

RoadXYZ
Explorer II
Explorer II
Not sure what is happening - but - whenever flush the toilet it appears that the AC fan is sucking in the smell ... can this be the problem ?

Or ?

New vent installed in 2013 for toilet .. it is the swivel type ..
Full-Time RV'rs - Grandma Marji, and Grandpa
2008 Suburban / 2004 Alpenlite TT(FT)
10 REPLIES 10

Kiki1964tx
Explorer
Explorer

Make sure the black tank pipe extends a couple of inches above the rv, and it is sealed. Our black tank pipe did not extend all the way through the ceiling. We added an extension pipe to bring it a couple of inches above the roof and sealed around it. No more black tank smells when flushing.

I am sure your information would have been helpful to the OP, but you are responding to a post that's 10 years old and the OP hasn't been on here since. I am not sure why the developers of this new site haven't taken our repeated feedback and lock old posts, but this site has literally no support. 


Jeff - 2023 FR Sunseeker 2400B MBS

spike99
Explorer
Explorer
.

Unknown to many folks, many RV toilet system do NOT use goose-neck piping system - to keep the bad smells within the holding tank. If one opens up the toilet valve and looks directly down the hole (assume one's RV had straight pipes), one can see the top of their inner holding tank contents. Yes, they see the TP and other "stuff". When one turns the bathroom ceiling fan ON (especially on high speed) while the bathroom door is closed, and opens the toilet valve, the "bad smell" is sucked up / out of the open toilet valve hole. After all, replacement air always takes shortest path first.

Methods to resolve:

Add lots of water to each previous flush. Thus, one "dilutes" the bad smell inside the holding tank. And, because one is using more water to flush, they must empty their RV's holding tank more often - since Tank fills up faster. This method reduces the time interval when the "stuff" starts to stink as well.

Add lots of chemicals down the toilet hole. This dilutes and/or masks the bad smells. This becomes costly in the long run. And, many folks like me don't like using chemicals.

Keep the ceiling fan OFF when sitting down and when flushing. Especially when the bathroom door is closed. Thus, air replacement "up the hole" doesn't happen. Only turn the ceiling fan on AFTER one washes their hands and leaves the bathroom (with bathroom door closed).

Install a store bought 12V fan and install within the black tank's air vent pipe. With this upgrade, simply turn this special fan ON, sit down, do one's "stuff", then flush the toilet. The vacuum created inside the black tank sucks air "down" the open toilet hole (and pushes out its roof top vent pipe). With this upgrade, its near impossible for "bad smell air" to naturally float up and out the open toilet hole. And best of all, NO chemicals to add or extra water to add either. Simply install this fan and use it.

If wondering, I created my own RV roof top "power vent" system using ABS Pipe, 12V computer fan (35+ CFM) and a manual off/on switch. Very simple DIY creation. After I installed this special upgrade, I never got bad smells inside my TT's small bathroom again.

For store bought fan solution (that can be installed within RV walls or within empty roof cavity), surf: - click here -

IMO, this inline fan should be factory build (since RV toilet plumbing doesn't use gooseneck piping). If wondering, my next TT with onboard toilet will get this special fan installed again - without hesitation.

.

RoadXYZ
Explorer II
Explorer II
We put the tank deodorizer from the RV dealer in both the black as well as grey tanks, and the smell is 90% gone ... thanks for the suggestions.
Full-Time RV'rs - Grandma Marji, and Grandpa
2008 Suburban / 2004 Alpenlite TT(FT)

2oldman
Explorer II
Explorer II
In hot weather, the longer the black stuff remains, the smellier it gets. Probably nothing you can do short of dumping and rinsing.
"If I'm wearing long pants, I'm too far north" - 2oldman

RoadXYZ
Explorer II
Explorer II
Thank you for the replies .. now wondering if it is when I refill the toilet .. we the water pump on so we know when the water pressure in the campground is low, and so we have to put our foot on the pedal to refill the toilet ...

Emptied the tank this afternoon, and will be putting in a deodorizer in a few minutes .. hope that helps .. have been using the Geo Method ...
Full-Time RV'rs - Grandma Marji, and Grandpa
2008 Suburban / 2004 Alpenlite TT(FT)

ScottG
Nomad
Nomad
Many of our tanks have the vent stack pushed too far down into the tank (mine is). So when it gets fairly full (about 3/4 in my case) the vent is submerged and useless. Then it gets nice and warm in there and the pressure burps through the toity.
All you can do is dump more often.

sch911
Explorer
Explorer
2oldman wrote:
I wonder if the tank contents are hotter, and therefore at a higher pressure, than the cooler inside.


Don't think this could happen with a functioning vent.
OEM Auto Engineer- Embedded Software Team
09 Holiday Rambler Endeavor 41SKQ Cummins ISL
2012 Jeep Grand Cherokee Limited Toad

2oldman
Explorer II
Explorer II
I wonder if the tank contents are hotter, and therefore at a higher pressure, than the cooler inside.
"If I'm wearing long pants, I'm too far north" - 2oldman

sch911
Explorer
Explorer
The A/C only recirculates the air inside your RV so there is no suction or vacuum created. A vent fan does pull air out of the RV and that can be the culprit. But there are other potential causes like a plugged sewer vent line, or a vacuum break valve stuck open.
OEM Auto Engineer- Embedded Software Team
09 Holiday Rambler Endeavor 41SKQ Cummins ISL
2012 Jeep Grand Cherokee Limited Toad