Black tank odor - switch to macerating toilet?

[belfert]

4 or 5 90's is the same as no vent. You need to vent it straight through the roof. Rv's and travel trailers figured this out several years ago. It's not the valve closing properly or not holding water. Go look at a Job Johnny. The hole can be wide open and the smell goes up the vent pipe. The toilet hole where it connects to your tank, needs an extension of two or three inches. Your vent pipe should connect with an inch or less intrusion into your tank. Also, a bathroom vent fan can help in those situations where the vent gets into a down draft.

What if there is no possible way with the current construction to have a vent straight out of the tank?  The only way I could possibly make it work would be to demolish the entire bathroom and probably eliminate the shower altogether during the rebuild.  There are no walls directly over the tank.  I could get down to two 90s with minimal work.  Two of the 90s were me being lazy and not realizing the extra 90s would cause issues.

I might even have to have a new waste tank built at a cost of $2,000 or so.

[RichardEntrekin]

A concept to consider is adding a powered ventilator to the black tank vent. All kinds of challenges in doing that, but the idea is to pull enough air out the vent that when the toilet pathway to the tank is open, air flows into the toilet opening instead of out of it.

[richard5933]

...Other than when the bus is in motion, we rarely have odor problems...

Just to clarify, the only problem is if someone flushes while we are in motion. Otherwise, no problems while in motion. Not sure if it matters to anyone else consider plans moving forward, but thought I'd clear that up.

[kyle4501]

Antibacterial soaps & cleaners will kill the good bacteria in the waste tank which will create more foul odors.
Alcohol consumption will also add significantly to the stink.

In our coach, if we didn't 'process' it normally, we don't put it in the toilet. NEVER any paper (- we use a foot pedal trash can for paper).
We don't have any foul odor problems with our holding tank (it is a combined tank, 100+ gal).

Would a marine "In Line Marine Bilge Blower" in the vent line assist in the venting past all those bends?

[buswarrior]

Other than when the bus is in motion, we rarely have odor problems.

Make those bigger, and out of pipe, and you will then have no odour problem. That's exactly what gets done wrong on boats, little piece of hose, heading down. And use the wrong hose, the hose absorbs the stink and gives it off in the bilge/baggage bay.

Like pregnancy, there's no such thing as a little odour problem.

Eliminate it!!!

Happy coaching!
Buswarrior

[belfert]

A concept to consider is adding a powered ventilator to the black tank vent. All kinds of challenges in doing that, but the idea is to pull enough air out the vent that when the toilet pathway to the tank is open, air flows into the toilet opening instead of out of it.

LSL Products used to make a few different powered ventilators for tank vents in RVs under the Lil Stanker brand, but they discontinued them and all of their RV products it appears.  They still make a Super Stanker vent fan, but it is intended for a house and is huge with a 4" opening.

I looked at a 12 volt ventilator for a battery box, but it is only 8 CFM.  The Super Stanker and the old Lil Stanker are/were around 40 to 50 CFM.  I think boat bilge blowers might suck too hard at over 100 CFM.  I was thinking about building my own ventilator, but the hard part would be finding a fan that runs slow enough to do around 40 CFM.  I don't know if I could run say a 24 volt fan at 12 volts to make it run slow, or if the fan simply would not turn at all.

[Lin]

Maybe something like this will help.

https://www.amazon.com/Ultra-Fab-53-945001-Solar-Plumbing-White/dp/B004UQV3II/ref=sr_1_2?keywords=solar+rv+vent&qid=1571100684&sr=8-2

[richard5933]

Or if your budget allows, something like this: https://www.amazon.com/ZEPHYR-POWER-VENT-BATTERY-BOX/dp/B01HBZJ0NO/ref=sr_1_16?keywords=battery+power+vent&qid=1571101316&sr=8-16

We use one on our battery box. Pretty much has been running non-stop for two years now. If it can tolerate battery gases, I assume it can tolerate black tank gases.

Regardless of the fan you choose, you could easily wire it to come on with the bathroom lights or with a separate switch.

[oltrunt]

Gary, I'd pay for a weeks rent an a trailer potty if you'd drag it to Lake mead in a couple of weeks!
Jack

[chessie4905]

At least eliminate two of the 90's.

[DoubleEagle]

Don,

With all due respect:

We installed an efficient house toilet in our last bus. Yes we loved it. Absolutely. But no, it cannot compete with the water usage of a gravity toilet. No contest. We would fill a 100 black tank in very short order when underway. I absolutely do NOT recommend a house toilet if you want your fresh tank and black tank to last more than a few days. Trust me on this.

Scott, what is the GPF rating of the toilet you used, and did it require more than one flush at times? There are models available now such as the Japanese TOTO Drake II which uses 1.28 GPF, and is very effective, according Amazon reviews. If the reviews are correct, it would seem that it would last more than a few days.

[chessie4905]

I have one of those American Standard toilets in the house that was featured in ads a few years back that could flush a bunch of golf or ping pong balls. With attention to use, you can flush with only a quart of water for #1 and 2 to 3 quarts for #2.
Make sure the vent to roof is at least 2 1/2 inches.
"Only have odor when on the road" Then it needs better venting. But I know you are not going to tear up the interior now. You can put your Fantastic vent fan in the bathroom on low when in transit.
This discussion should be of benefit for those doing a conversion.

[belfert]

I originally did the majority of my conversion project during spring and summer 2006.  The bathroom ended up being way too big.  A few years later I took everything out of the interior of the bus and essentially started over.  This time I tore up the floor and the seat rails and put down new plywood subfloor.  I had vinyl tile installed on the floor before putting everything back inside.

During the redo I shifted the water and waste tanks from one side of the bay to the other side of the bay to make the bathroom smaller.  The location of the toilet over the original opening in the tank dictated the new size of the bathroom.  I was lazy and didn't want to cut a new hole in the roof for the waste tank vent.  The wall was in the same place so I simply put two 90s to connect the new pipe out of the floor with the hole in the roof.  I didn't think it would matter as air could still move through the pipe.

I can pretty easily move the vent pipe to go straight up to the roof at a new location.  I had a new stainless tank made five or six years ago to replace my plastic tank that was starting to drip a bit.  I had a connection added to the top of the tank to vent the tank with fewer 90s, but again too lazy to redo the vent to use the new connection.  I will fix that next summer.

[belfert]

I currently have just one 3" connection into the tank so the toilet can drop straight down.  I put a tee in the 3" line with two 2" lines for the shower and the bathroom sink.  The line to the vent first takes a 90 towards the shower.  There is a tee for the shower and the line for the vent continues straight to a close 90 where it goes up through the floor into the wall.  In the wall there is a another 90 and then it goes over 15" or so to a final 90 that takes the pipe up to the roof.

[eagle19952]

Per Bus Nut Standards
I do everything my way. That said my black tank is vented to under my coach.via two 2" 90's and the pipe needed to put it 2-3 inches below the baggage bay floor. My Ball valve hasn't held water for years (I have replaced the seal too many times).We keep a 1 gallon garden spray with a soap solution to rinse the bowl of urine. It only takes a 1/2 inch of water to seal the bowl from the tank  Poop gets a full flush.
PS. Water contains oxygen, that's where your black tank gets it from.
PSS. My black tank has 2 90's and is 4-5 feet from the toilet drop.
PSS. I truly believe that flat/horizontal
tanks are worse/problematical than vertical
The only time it stinks is if the dog steps on the flush lever
Good Luck.