I am having serious problems with black tank odor. I travel with a bunch of friends and they tend to only open the flush valve the absolute minimum to keep the odor to a minimum. I replaced the entire flush mechanism on the toilet last year or the year before because it wasn't holding water. The flush valve is not holding water again and I suspect it is because people are not holding the valve open long enough and getting tissue caught in the valve mechanism. Replacing the valve is a major project.
One of the options I am looking at is a macerating toilet. The Dometic 7640 is the best macerating toilet I have found because it will dump through the existing toilet connection and it has a low water use mode. The issue with the low water use mode is it leaves no water in the bowl. It also still uses twice as much water as an RV toilet. With seven people using the toilet that can be a lot of extra water use.
My vent has four or five 90s in it so maybe it isn't venting well because of that. I use a Cyclone vent cap that is supposed to help pull out odors. I know some vent with flexible hose out the wheel wheel or similar, but would that just create odor issues at ground level?
Thoughts/opinions/whatever?
Is the problem while on the road or while parked?
We have a problem with odor if someone flushes while the bus is on the road. I'm guessing that a combination of a low-pressure situation inside the coach and air being forced into our vent as we move. No problem for us once we're stationary with the OTR HVAC system off.
If you're having a problem when the bus is parked, then look at your venting to see if it is clear all the way to the roof. The 90-degree bends aren't helping, but you may also have a blockage caused by a wasp nest or bird nest.
If your valve is holding water, then it's not the problem. Also not the problem if the odor is only there when you flush.
I've also found that if there is a lot of build up above the water line it can cause an odor problem. In this case flushing the tank does improve things some.
Are the people you're traveling with all men? If so, have you given though to installing a small urinal which feeds into tank through a duckbill valve? It would save on water and reduce the number of times the flush valve needs to be opened.
The boat peeps have an expert.
"The Headmistress" Peggie Hall has a book on these matters.
https://www.amazon.ca/New-Get-Rid-Boat-Odors-ebook/dp/B01BW2ZSTW
Basically, lack of oxygen is what makes bad stink. Proper venting is EVERYTHING.
Good oxygen, good bacteria do their job without stink.
No oxygen, bad bacteria do their job with lots of stink.
Chemicals kill them both, and leave you with another unpleasant stink, besides the perfume...
After the extensive testimonials on boat forums, extolling the dramatic changes in boats, after upgrading to Peggie's strategies, I will have 2 large vent lines on the waste tank in my new bus to promote good air exchange.
Happy coaching!
Buswarrior
I have a Dometic macerator toilet. A few comments.
They do allow a little bit of water in the bottom of the toilet after flushing. Sufficient enuf to keep any stink out. And you can add more before you leave it if you want.
They do take more water to flush. The water delivery (side cleaning) is not as good as some other toilets, if you put TP in the bowl, you always have to allow extra water in the bowl, until the paper floats, to basically unstick it from the sides of the bowl. This can take up to twice as much water as a good flushing drop toilet. Unless you use a toilet brush to push the paper into the water. If it is not in the water, it will not flush.
These tend to leave some "processed" food particles floating in the bottom of the toilet at all times. This can be prevented, again, by flushing the toilet up to 20 seconds or so to grind it up and flush it all down. A good drop toilet does not have the pump in the way impeding everything from going down.
If you put ANYTHING down these toilets, it will have problems. One time I removed a gum wrapper out of my impeller after letting an employee use it.
If/when your pump stops working, a replacement pump is about $350. It is an easy replacement but does take an hour or so. I am on my second one.
The advantage of a macerator potty is that there will be zero build-up of solids in your tank. Your tank will flush nicely and you can leave both your black and grey water tank open all of the time. This may be advantageous if you plan to be in a location for a long time and don't want to bother emptying out your tank very often.
I recommend using a macerator toilet only if you have to either pump your waste uphill, or if your black water tank is not in a position either directly under your potty, or close enuf for the wast to flow thru your black water pipe sufficiently. You can go 3" with very little slope and will be fine as long as you listen for the plop to ensure everything has exited the horizontal (or almost horizontal) drain pipe.
I have had my macerator potty for about 5 years now, I am on my second pump, and it never flushes 100% and my bus still stinks, especially after dumping my tanks and starting out down the road. So I do not believe using a macerator potty will solve the stink problem, but I am sure a lot of other people can suggest solutions for that, such as ensuring your tank is properly vented, and maybe putting a solar fan on your roof on top of your stink pipe etc.
Good luck.
Flushing while underway...
The stock HVAC should be pressuring the coach, not depressurizing it.
An open window or roof vent will defeat the HVAC and create negative pressure to suck toilet gas into the coach.
If the tank vent is in the breeze, change the cut on the top to make it suction at highway speed, nothing will stop a pressurised tank from blowing into the coach when the trap is opened.
If it can't be used "normally"...
More S H I T that the riders are forced to deal with? LOL
The Busnut doesn't have to endure this particular irritant, because he's always stopped when it's time to pee...
Beat that damned toilet into submission. It's yours, and you are it's Master.
Happy coaching!
Buswarrior
One simple thing that should be done with a gravity ball valve toilet. When mine stops holding water, I simply take a round toilet brush and brush out the ball valve opening. It doesn't ruin the seal, and after that the ball seals properly. I don't want the hassle of up keep of a macerator toilet. Good Luck, TomC
Another angle to this problem is using a conventional toilet instead of the RV style. There are many low water flush models out now that would probably compete with the water used in a macerator setup. The cost is in the $200 plus range, and they would be more home-like. I am heavily considering one for my next redo.
I have had many toilets in the 20 years I have been in the RV world, and 15 years of full-timing. Most seem to last only 2-3 years in full-time use. As TomC noted, the round ball type valves do tend to stay cleaner and are easier to clean, but I do not like the looks of them as well as the slide-type. The slide-type do tend to clog up more. The slide mechanism should be cleaned regularly with a toilet brush but the design is not really suitable for a potty in the first place. Once they stop holding water, they start letting gasses escape and stink up your house. I have found they need to be replaced every couple of years of full-timing, but the last time I did that, the cable broke shortly after that and I bought a new potty. After that, I decided it was not worth fixing a toilet, now I just go out and buy a new one. Drop type toilets even with porcelain bowls are not that expensive and frequently on sale and then you don't have to worry about it for another couple of years.
Not sure about you but every time my potty broke, It was after hours or on a weekend and it was very inconvenient to get to an RV store, so I reduce the chances of that happening buy just replacing them when they start to act up now. Thankfully my macerator potty has lasted longer than any of them but at $1000 a pop, they had better.
I have a Thetford Aria Classic toilet with a slide valve, not a ball valve. I am considering getting the Dometic Sealand 510 simply because it has a ball valve. It sounds like macerating is not a good idea. Drop is direct into the tank.
My stock HVAC is long gone. We use rooftop A/C and don't typically open any windows. I have a Cyclone vent cover that is sorta like a weather vane and turns whichever way the wind is blowing.
With seven people it is impossible to stop every time someone needs to use the bathroom. One of the reasons to get a bus was to reduce the food and restroom stops to a minimum. It was wasting a lot of time when every stop took a minimum of 30 minutes by the time everyone was rounded back up. I am pretty sure I don't have room for a urinal plus don't they use a lot of water?
Thanks for the responses so far.
Quote from: buswarrior on October 14, 2019, 08:17:38 AM
The boat peeps have an expert.
"The Headmistress" Peggie Hall has a book on these matters.
https://www.amazon.ca/New-Get-Rid-Boat-Odors-ebook/dp/B01BW2ZSTW
Thanks much. I got the Kindle version of this book from Amazon and will read it on my iPad on my transit bus ride home tonight.
If there is no water in the bowl, it seems it is always possible to get some odor. The worst odor comes, as mentioned, from the anaerobic bacteria, so air flow can be very important. If the bus has been sitting for a while, that bacteria can develop even if there is airflow when you start to move. We use some septic tank enzyme as a tank treatment. It's very cheap and seems to help.
The ball valve on our toilet does not always seal properly on its own. However, if you lift up on the pedal, which adds water to the bowl, it also closes the valve more securely. I find that I have to clean and lube the gasket every now and then. One must be careful though to not use a lube that damages the gasket.
If all else fails, this should solve your problem. ;D
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.
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.
Quote from: Gary Hatt - Publisher BCM on October 14, 2019, 02:16:19 PM
If all else fails, this should solve your problem. ;D
We actually half seriously discussed renting a porta potty as a group while camped at an event. We generally use the event supplied porta potties during the day to cut down on filling the waste tank. Sometimes the potties are a decent walk away. The rental company usually doesn't have any more space for another potty so that ended that idea.
Quote from: chessie4905 on October 14, 2019, 04:16:18 PM
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.
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.
...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.
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?
Quote from: richard5933 on October 14, 2019, 04:47:35 PM
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
Quote from: RichardEntrekin on October 14, 2019, 04:41:17 PM
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.
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
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.
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
At least eliminate two of the 90's.
Quote from: Scott & Heather on October 14, 2019, 03:54:26 PM
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.
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.
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.
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.
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.
Just to clarify that when I said we only have problems when the bus is on the road and in motion I was talking about if someone flushed while we were moving.
No problems with odor while on the road unless the toilet was flushed, then those few seconds allowed odor to be sucked into the bus.
Don,
1.28 gallons per flush...we have four people living in our bus. That's four flushes first thing in the morning, and several sets of those throughout the day. If each of us only flushed three times a day (and I'm telling you, we flush more than that) the 100 gallon tank would only last around 6 days. That's not enough for us when we are traveling heavily or boondocking in a parking lot. And in real life practice the tank only lasted about 4 days. Just not enough. And chessie, there ain't no house toilet that flushes only a quart or two. 1.28 gal is The minimum. Rv toilets actually do flush only a quart per flush. Literally 1/5th what a house toilet flushes.
Maybe I'm a quart low, I haven't measured it. I know it uses far less to flush than any toilet I ever used. Your situation is a little more elevated than normal for most rv owners; some could probably use a low flow household toilet, but, if a Job Johnny can have that seat hole wide open with no odor in the enclosure, then it is worth checking out. They do use a 3 inch vent though. Since moving RV's have various airflow while in motion, a fan vent in ceiling of bathroom on while travelling is probably one of the easiest ways to deal with odor issues.
I find on my bus that having the bathroom vent fan on when flushing draws in even more odors when the flush valve is open to empty the bowl.
In some (most) cases a fan vent on while toilet flushing still won't overcome the ambient vaccume that exists in most busses while going down the hwy, especially if the drivers window is open! We just grin and bare it - it's a very fast passing event...
Quote from: buswarrior on October 14, 2019, 08:17:38 AM
The boat peeps have an expert.
"The Headmistress" Peggie Hall has a book on these matters.
https://www.amazon.ca/New-Get-Rid-Boat-Odors-ebook/dp/B01BW2ZSTW
Basically, lack of oxygen is what makes bad stink. Proper venting is EVERYTHING.
I am about two thirds of the way through the book. One of the big takeaways I got from the section on venting is the recommendation to only go horizontal with the vent and not to go over five feet with three feet even better.
Is bacteria really going to take care of the smell if my tank is getting up to 10 deposits of #2 per day?
Quote from: belfert on October 16, 2019, 06:22:36 AM
I am about two thirds of the way through the book. One of the big takeaways I got from the section on venting is the recommendation to only go horizontal with the vent and not to go over five feet with three feet even better.
Is bacteria really going to take care of the smell if my tank is getting up to 10 deposits of #2 per day?
Actually, I've been reading that much of the odor in the black tank actually comes from the urine in the tank, not the solid materials. Makes sense, as anyone walking into a campground restroom with non-functioning urinals can attest to.
I think separating out the urine from the solids is how composting toilets can function without odor problems.
When we had horses, the smell emanating form the manure pile was always less troublesome than the urine which would seep under the rubber mats and turn rancid.
Maybe better sealing of the bathroom door and enclosure is a thought. Maybe the smell you have is coming up through the mouse holes in the floor from your non roof vent. If yout toilet has a good water seal, sink and shower traps are working, where is the odor coming from? Is the water seal bubbling? This has been an ongoing issue for years for scores of bus nuts.
The odor is almost entirely from when the toilet is flushed. There will be a terrible stink when someone flushes the toilet.
Multiple little things adding up?
The drop from the toilet shouldn't be the highest opening in the tank, the vents should be. How far do each protrude into the tank top?
The gases will COLLECT up high in the drop from the toilet and whoosh up into the coach when it gets opened.
The vents should be as flush with the inside top surface of the tank as possible, so the gases go there and leave continuously, not storing in the toilet drop.
The vent(s) have to be big enough and straight enough that there actually is air flow.
Is the end of the tank vent in a high pressure area, or unwittingly catching the wind, instead of shedding gases to the passing wind?
Underbody cavities, who knows whether any particular one, or area, on whichever coach, with whatever fenders, might happen to be a high pressure area?
While underway, opening a vent or window only makes the suction pulling the odours into the coach stronger.
It may disperse the odour faster afterward, but it triggered the gulp of stink in the first place.
Re: horizontal runs.
Buses have the freedom to go vertical. Boat writing focuses hard on the word "horizontal" because the vent is going exclusively out a fitting in the side of the hull, below the edge of the deck. Many manufacturers and peeps retrofitting, leave loops or aim then conveniently down, without realizing that airflow is being hindered.)
Lots of variables to have accidentally have a stinky experience.
Happy coaching!
Buswarrior
no free lunch with any toilet ( stink any way ) I have a headhunter water jet toilet similar to below and there is zero smell when you flush but it uses water to do that . the only bad smell is from the person making the stink . the water jet blasts the "stuff " as it is going out of the toilet like a pressure washer
sure glad that I did not pay for it
https://www.headhunterinc.com/product/espresso/
dave
Actually if you research toilet odors you find that most of the stinky gases are heavier than air. How about that, huh? So what is actually happening in your black tank is that the gases are accumulating, building up, and pushing the air out the top of the tank vent so that now you have a stack of stinky gas just waiting on you to open the toilet valve so they can drop down into your bathroom. If you're moving, have a window cracked, and run the bathroom vent fan so much the better! (worse) Maybe this is why some of our guys with low vents are getting by with it. But that does mean stink around the wheel well.
The solution is to get those stinky gases replaced with fresh air, send them up high and disperse them in the wind like they should be, but this takes energy. Maybe not a whole lot, but at least enough to scavenge the black tank. That means a minimum of two vents, one of which is fitted with some means of generating a slight suction. Could be a bilge fan connected to the bathroom light switch. Could be one of those fancy wind powered vent caps. Could be something else entirely. Could be run on compressed air for instance. Could be solar. But the key is, it has to scavenge the tank effectively. That's not really asking that much, it could be constant, intermittent, or on-demand. Could be high flow or low flow. But the bottom line is, if you blow those heavier than air gases out of the holding tank before you open the valve there will be no stink to climb up the toilet into your bathroom. And you have the side benefit of promoting aerobic bacteria in the tank, further reducing the stink. Win-win.
Jim
I have a special adapter that goes on the top of roof that vents to suck air out of the black tank while driving.
Geoff, add a second vent line to let fresh air into the tank and you should be able to further improve your system. Try to go for the opposite corner of the tank.
Jim
Maybe a constant small flame at the vent pipe outlet. Should look good at night.
Quote from: buswarrior on October 16, 2019, 08:32:39 AM
Multiple little things adding up?
The drop from the toilet shouldn't be the highest opening in the tank, the vents should be. How far do each protrude into the tank top?
I have a 100+ gallon rectangular waste tank made of stainless steel. Both the vent connection and the toilet connection are simply female fittings welded to the top side of the tank so they are both at the same level. I suppose I might be able to have a pipe or tube welded in so the toilet waste drops further in. The issue there would be if the tank ever filled up close to that pipe/tube I would have a mess. I would end up with nasty stuff all over the outside of that pipe/tube.
I'm missing something. It should only go into the tank about 4 inches. Be a good gauge when it is getting full. No need to weld a sleeve. How about thinwall pvc of the size to slip inside the welded sleeve? You could glue it into place. Maybe Gorilla glue or Shoe Goo. Many fuel tank filler necks are designed that way.
Quote from: chessie4905 on October 16, 2019, 03:10:45 PM
I'm missing something. It should only go into the tank about 4 inches. Be a good gauge when it is getting full. No need to weld a sleeve. How about thinwall pvc of the size to slip inside the welded sleeve? You could glue it into place. Maybe Gorilla glue or Shoe Goo. Many fuel tank filler necks are designed that way.
See the attached photo. The connection at the tank is threaded. The right side connection eventually goes to the vent. I have a smaller connection on the top of the tank on the far side of the tank that was/is intended to be the vent, but it is plugged right now.
I did lots of research before doing my plumbing and never heard of placing the toilet pipe down into the tank until today. I would have designed the tank differently if I knew that back then. I might be able to get a pipe 4" into the tank, but I'll lose close to 25% of tank capacity.
You won't lose any capacity. Level will still rise in extension as before without. The liquid will still seek level. Just like in a gas tank.
That's the good thing about usuing pvc. You can pry it out if it doesn't work for you. Start with a 2 1\2" stub first.
Quote from: belfert on October 16, 2019, 04:19:08 PM
See the attached photo. The connection at the tank is threaded. The right side connection eventually goes to the vent. I have a smaller connection on the top of the tank on the far side of the tank that was/is intended to be the vent, but it is plugged right now.
I did lots of research before doing my plumbing and never heard of placing the toilet pipe down into the tank until today. I would have designed the tank differently if I knew that back then. I might be able to get a pipe 4" into the tank, but I'll lose close to 25% of tank capacity.
Hum, my black tank vent is just like yours, only it attaches to the grey tank vent at the same level using a tee. So this way if the black tank over flows, it goes into the grey tank. I have never over flowed the grey tank.
This thread is cracking me up. I especially liked the idea of lighting an open flame at the top of the vent Hahahah. Chessie...
You just can't eliminate the smell when flushing while underway. But I can tell you that the toilet in my master half bath doesn't stink nearly as bad when we flush as the toilet in the guest bathroom. That one has a straight drop whereas my master bath toilet actually has a three foot horizontal run before dropping in the tank. That actually makes a difference believe it or not
Hey Scott forgive me for saying this but that's like saying your $#!% don't stink! Lol
In New York State, back in the 1970's, at least, the plumbing code for residences required a fresh air inlet (four inch pipe if the drain was 4") to be located near the point where the drain pipe exited the foundation. This enabled a flow of air through the drain pipe and up the vent stack. This principle might work in our buses as well with an inlet vent just above the tank on the side of the bus, and then a vent stack up through the roof. A booster fan should help the process, but might not be necessary.
The rationale for having the RV style toilets right over the tank is probably because of the small amount of water used, and the chances of deposits building up in horizontal pipes. In house plumbing, the slope of the pipe is one-eighth inch per foot, because a steeper slope allows the water to run off more quickly, leaving the solids behind. In our situation, with less than level conditions often, finding the correct slope is more difficult. Maybe a home style low water toilet right over the tank with large air intake pipes, and vent pipes, is the best solution. We need someone to test this and report back! ::)
You know what is amazing to me? City sewers are. Now you would expect them to stink like your holding tank, right? And to be fair they ain't no flowerbeds. But they don't stink anywhere near as bad as you would expect. Certainly tolerable for anybody to put up with for an extended period if they must. By no means pleasant mind you, but nowhere even remotely close to what blows out of the RV toilet. Also what runs through 'em is a surprise. You never see any brown trout or other lumpiness washing by, it's all dingy water and some grease build-up in places, along with a fair bit of gravel, maybe some rag, and the occasional ring. What the heck is up with that? Apparently everything liquefies by the time it gets to the curb. How's that for a surprise?
By comparison a RV blackwater tank is a seriously nasty, nasty place.And there's got to be a reason for that. Apparently it's totally a matter of letting the air get to it, well that and letting the gas get away I suppose. But the good news is that if they can do it we can do it. It's just a matter of figuring out how.
Jim
I'm planning on using a flushmate pressure assist toilet that flushes 1.0 gallon per flush. It will be installed directly above the black tank. It has a sealed tank so no problem with water sloshing in the tank and it should do a good job keeping out odors due to some water in the bowl. I hope this is a good plan.
Quote from: Scott & Heather on October 15, 2019, 11:31:08 PM
Don,
1.28 gallons per flush...we have four people living in our bus. That's four flushes first thing in the morning, and several sets of those throughout the day. If each of us only flushed three times a day (and I'm telling you, we flush more than that) the 100 gallon tank would only last around 6 days. That's not enough for us when we are traveling heavily or boondocking in a parking lot. And in real life practice the tank only lasted about 4 days. Just not enough. And chessie, there ain't no house toilet that flushes only a quart or two. 1.28 gal is The minimum. Rv toilets actually do flush only a quart per flush. Literally 1/5th what a house toilet flushes.
The answer is very simple ;D, I pump a small amount of compressed air from the bus into my tanks while driving
I also vent my tanks ( 40mm ) back to a venturi in the engine air intake, before the air cleaner.
I also have a small fish tank air pump that I can use if stopped for some time. the air is pumped in the bottom of the tanks and bubbles up through the contents = no smell ;D
Quote from: Toolman on October 17, 2019, 01:48:25 AM
The answer is very simple ;D, I pump a small amount of compressed air from the bus into my tanks while driving
I also vent my tanks ( 40mm ) back to a venturi in the engine air intake, before the air cleaner.
I also have a small fish tank air pump that I can use if stopped for some time. the air is pumped in the bottom of the tanks and bubbles up through the contents = no smell ;D
Interesting what you say here, especially considering what chessie4905 posted in another thread about the OEM air cleaner on the Buffalo buses. Apparently there is a 2" tube running from the holding tank venting system to the air cleaner. Whenever the engine runs, it is sucking from the holding tank's vent and pulling the odor into the engine.
Maybe that's the answer to keeping the black tank from releasing odor when flushed while underway. Route a piece of tubing from the vent to the engine air cleaner. I know, our tanks are much further from the engine the the factory bathrooms, but something along those lines obviously would work or the factory wouldn't have wasted money doing it.
If you have all that odor when you flush, then your vent is too small.
Of course city sewer don't smell as bad. The water compliment of the sewage is far higher, and includes grey water.
Quote from: Toolman on October 17, 2019, 01:48:25 AM
The answer is very simple ;D, I pump a small amount of compressed air from the bus into my tanks while driving
I also vent my tanks ( 40mm ) back to a venturi in the engine air intake, before the air cleaner.
I also have a small fish tank air pump that I can use if stopped for some time. the air is pumped in the bottom of the tanks and bubbles up through the contents = no smell ;D
Some real good ideas right there. I like the fish tank pump idea, never thought of that one. Running the vent to the air cleaner is good too, sorta like propane injection! ;D The compressed air leak is a no cost option too, do you run that into your bubbler for the fish tank pump?
Even with all that I also think it would benefit from a second vent, maybe to the roof with some active means of creating airflow just to scavenge the tank.
Good point about the extra water in the city sewer. Maybe that's a vote for combined tanks, or at least extra water when flushing.
Jim
Quote from: Toolman on October 17, 2019, 01:48:25 AM
The answer is very simple ;D, I pump a small amount of compressed air from the bus into my tanks while driving
I also vent my tanks ( 40mm ) back to a venturi in the engine air intake, before the air cleaner.
I also have a small fish tank air pump that I can use if stopped for some time. the air is pumped in the bottom of the tanks and bubbles up through the contents = no smell ;D
So you are venting Methane gas into your engine?
Quote from: Dave5Cs on October 17, 2019, 07:45:24 AM
So you are venting Methane gas into your engine?
Sounds like GM did that with the OEM bathroom. Don't think that there's enough methane concentration in the black tank to make much difference. The suction created by the air intake would probably result in the air in the black tank exchanging rapidly as it pulls fresh air in the tank's vent, diluting whatever methane may be present.
;)
My tank vent is 1.5" and I can't really go larger right now because the hole for the vent in my tank is only 1.5". I could probably have a larger connection installed, but that is a lot of hassle and money.
My plan for next year is to run a new vent to the roof with a fan in line to pull air through. I will then use the current vent connection to run an air intake to the tank. I will also look at putting the toilet pipe further into the tank, but I haven't figured out a way to do that yet. I haven't found any size of pipe that could be glued to the inside of the 3" pipe with no gap.
I have a combined black/grey tank. I planned separate tank originally, but I couldn't make it work space wise.
I have a 4106 with a combined 100 gal tank, 1/12 in kitchen/bathroom sinks going to the corner of the tank. The toilet is a straight drop. The tank is located at the front of the rear compartment. The kitchen/ bathroom sink drain goes on up to the roof to a boat scupper valve with the rubber flap cut out,in other words flat to the roof. I also have a 1 in hose going from the tank across and down the outside of the rear compartment to about 4 in below the bottom of the bus which I have cut off at a slant like the old draft tubes on the early cars. I have no odor while flushing unless I have a front window open which I rarely do. :)
Quote from: chessie4905 on October 16, 2019, 10:06:27 AM
Maybe a constant small flame at the vent pipe outlet. Should look good at night.
;D Great idea. Just like a refinery. ;D
When I run with my driver's window open, my bus stinks especially if I just dumped. Guessing it is creating a negative air pressure in the bus and sucking the fumes from the bathroom up to the window next to my nose. It maybe from all of the cracks around the toilet or something. But because my Sh$% don't stink, it doesn't bother me. :o
Well, gotta weigh in with so much enthusiasm for such a hot topic! ;)
In fact, this discussion has offered the best explanation about a feature in the bus bathroom. The bathroom is fully enclosed with a spring loaded exterior wall vent, sliding window, and solid door. Inside the bathroom vanity cabinet is a decent sized, variable speed fan that draws in air from a vent to the hallway and exhausts into the vanity base. Based on all the commentary about controlling the smell, I'm thinking the fan provides sufficient positive air pressure to keep the fumes from entering the bathroom and exhausting the foul smells. Nothing else has come close to explaining why the heck it was installed. It's always baffled me just why it is there.
My black and grey tank vents are linked together and draw there air in through the tank overflow which exits to the ground.
The air bubbler lines are teed together with a non-return valve in the air pump line
The whole system works much better than I ever imagined
I am in Australia and hold my tanks for more than a week in 37deg temps with no smell when I dump
Again, simple you can not have too much air flow through your tanks ;D
Is that degrees or Celsius? Odeor isn't as big a problem at low temperatures.
Sorry, Celsius. = Warm ;D
My Bus is also a little Different
A Tool Van that has a living area in it
https://photos.app.goo.gl/oiJ2LNjqYvWgcRgg6
Toolman
any inside pics
dave
Sharp looking rig.
https://photos.app.goo.gl/PpNVamXmuKdUUMg46 (https://photos.app.goo.gl/PpNVamXmuKdUUMg46)
Having trouble with these photos :(
https://photos.app.goo.gl/MzkgE7teuZvVBF8CA
https://photos.app.goo.gl/9ZAi7JZ6pnhCJjTJA
I hope that you get the idea ;D :D
Toolman do you have a pic of the air vent going to your engine air intake? Not quite sure what you mean by a Venturi. Thanks
Quote from: Toolman on October 17, 2019, 01:48:25 AM
The answer is very simple ;D, I pump a small amount of compressed air from the bus into my tanks while driving
I also vent my tanks ( 40mm ) back to a venturi in the engine air intake, before the air cleaner.
I also have a small fish tank air pump that I can use if stopped for some time. the air is pumped in the bottom of the tanks and bubbles up through the contents = no smell ;D
No photo, I would have to take the air intake apart. It is nothing more than a 1-1/2" pipe welded into the air intake. The pipe protrudes into the airstream alittle with the upstream side of the pipe maybe sticking out 1/4". the other side is level with the intake. Simple way to create a low pressure area = suction. Hope I make sense. :) It was already in the bus to draw air flow through the bathroom as has been talked about.