Cassette Toilets - Why Not?

[GeorgeRa]

Originally Posted by avanti

Absolutely not!
As we have discussed many times, a properly functioning RV black tank system won't smell any more than your home toilet (i.e., not at all). Unlike a cassette, a plumbed toilet is completely and permanently sealed (except during the 1-2 second flush time)……………..

My cassette is as sealed as toilets with ball valves in our previous RVs, I don’t understand your point “a plumbed toilet is completely and permanently sealed”

[GeorgeRa]

Originally Posted by avanti

In what way does a cassette toilet save interior space compared with a plumbed toilet? Couldn't you build the latter into a hassock/ottoman if you wanted to?

Plumbed toilet takes less space than cassette, no cassette and no water tank. It could easily be built in to an ottoman. A macerator toilet could be placed anywhere which was Dave’s decision for his new ARV van. Interior space would be saved if the toilet would be built into a full height bathroom.

[avanti]

Originally Posted by GeorgeRa

My cassette is as sealed as toilets with ball valves in our previous RVs, I don’t understand your point “a plumbed toilet is completely and permanently sealed”

So, any sewage system has an "inside" (smelly) and an "outside" (hopefully not smelly). The trick is to avoid vapor from leaking from the former to the latter. In both plumbed and cassette toilets, the main interface between the two is some kind of large valve--usually a slider that slides along a rubber ring. This ring can be problematic. In both systems, though, the top of the slider is made leakproof via a water seal. So far, the two systems are identical. In a good plumbed toilet, the BOTTOM of the slider is inside the system, so leakage here doesn't really matter. It CAN'T leak (which is what I meant by "completely sealed"). However, since the cassette needs to be removable, the bottom of it's slider is outside, and sealed only by a dry rubber seal. As I understand it, this is the reason they tend to have odor problems. An exhaust fan can help here by maintaining negative pressure in the "inside". As I said, I agree that this can work, but only if you are willing to leave the fan on all the time.

[michaelingp]

Originally Posted by GeorgeRa

Plumbed toilet takes less space than cassette, no cassette and no water tank.

Actually, our cassette toilet does not have a water tank, although some do. I agree that there is no space saving in theory, but in practice, all the plumbed toilets I've seen are located inside full height vertical enclosures which do take up a lot of space and affect the visibility and openness of the floor plan tremendously.

I'm not really trying to convince anybody to go one way or another. As Interblog requested I'm just reporting my own personal experience with a cassette toilet, and why I like it. Not only do I readily admit it's not for everybody, I can assume from the lengths we went to to get one, the market has already determined that most people would prefer the traditional toilet with black tank, or more likely in my opinion, most people would prefer an enclosed toilet with walls and that's usually going to be located at a place where it's easy to mount a black tank under the van and route the plumbing.

I may be more or less sensitive to odor than others, but odor-wise, our cassette is equivalent to the toilet plus black tank we had in our previous van. (I know that two toilets is not an adequate scientific sample.) I've done some searching on this forum, and some web-searches, and it still seems to me the conventional wisdom is to use chemicals in RV toilets of any type. There are certainly many more products on the market than I would expect if chemicals were only used on cassette toilets, which I believe are relatively rare.

[eric1514]

Originally Posted by GeorgeRa

I was facetious in my previous post responding to the post with negative cassette dumping prediction without experience. So, I fantasized about saturated toilet paper clumps projectiles and Hazmat suits.

During the last 7 years of using Thetford 402 Cassette toilet, I never had a spill, splash, leak nor odor problem. Emptying a cassette is not rocket science. For some the disadvantage of weight can be balanced by emptying frequency.

However, during my previous 25 years of using black tanks I had seen plenty of corn kernels processed by others.

My bad.

[GeorgeRa]

Originally Posted by avanti

So, any sewage system has an "inside" (smelly) and an "outside" (hopefully not smelly). The trick is to avoid vapor from leaking from the former to the latter. In both plumbed and cassette toilets, the main interface between the two is some kind of large valve--usually a slider that slides along a rubber ring. This ring can be problematic. In both systems, though, the top of the slider is made leakproof via a water seal. So far, the two systems are identical. In a good plumbed toilet, the BOTTOM of the slider is inside the system, so leakage here doesn't really matter. It CAN'T leak (which is what I meant by "completely sealed"). However, since the cassette needs to be removable, the bottom of it's slider is outside, and sealed only by a dry rubber seal. As I understand it, this is the reason they tend to have odor problems. An exhaust fan can help here by maintaining negative pressure in the "inside". As I said, I agree that this can work, but only if you are willing to leave the fan on all the time.

I use Thetford valve lubricant as recommended by Thetford on the cassette’s blade surface, and on the seal between the cassette and the blade. The blade has 2 motions, horizontal and vertical. At the end of rotating closing motion, it moves up to make a better seal. Seal between the bowl and the cassette seal is forced by 2 lips on the cassette engaging with bowl, see the picture.

Water in the ball is a good test for blade to cassette seal and bowl to cassette seal, see the diagram.

In regards to seals I see no difference between permanent toilets and cassettes if both are maintained. You can get replacement seals for regular toilet’s ball valve and a floor seal and a cassette seal.

If cassette waste space is not vented to outside any pressure buildup can ultimately cause odor, just like a black tank if net vented. Vent doesn’t have to be powered.

Is it possible that your experience with odor was due to lack of venting?

[GeorgeRa]

Originally Posted by michaelingp

Actually, our cassette toilet does not have a water tank, although some do. I agree that there is no space saving in theory, but in practice, all the plumbed toilets I've seen are located inside full height vertical enclosures which do take up a lot of space and affect the visibility and openness of the floor plan tremendously.

I'm not really trying to convince anybody to go one way or another. As Interblog requested I'm just reporting my own personal experience with a cassette toilet, and why I like it. Not only do I readily admit it's not for everybody, I can assume from the lengths we went to to get one, the market has already determined that most people would prefer the traditional toilet with black tank, or more likely in my opinion, most people would prefer an enclosed toilet with walls and that's usually going to be located at a place where it's easy to mount a black tank under the van and route the plumbing.

I may be more or less sensitive to odor than others, but odor-wise, our cassette is equivalent to the toilet plus black tank we had in our previous van. (I know that two toilets is not an adequate scientific sample.) I've done some searching on this forum, and some web-searches, and it still seems to me the conventional wisdom is to use chemicals in RV toilets of any type. There are certainly many more products on the market than I would expect if chemicals were only used on cassette toilets, which I believe are relatively rare.

I use this oxygen laden chemical for years - https://www.amazon.com/Valterra-Odor...e%2C234&sr=1-4

And this one for lubrication of cassette valve -
https://www.amazon.com/Thetford-Toil...624Z3Z43X8N1FJ

[avanti]

Originally Posted by michaelingp

I may be more or less sensitive to odor than others, but odor-wise, our cassette is equivalent to the toilet plus black tank we had in our previous van. (I know that two toilets is not an adequate scientific sample.) I've done some searching on this forum, and some web-searches, and it still seems to me the conventional wisdom is to use chemicals in RV toilets of any type. There are certainly many more products on the market than I would expect if chemicals were only used on cassette toilets, which I believe are relatively rare.

I can assure you that no one in the world is more sensitive to odors than DW.

How could a properly functioning plumbed toilet smell? If it smells, it leaks. (there is a previous thread that describes a certain specific line of toilets that had some kind of design defect that creates an internal vapor leak. I don't consider such a system as "properly functioning").

I never said that most people don't use chemicals. I said the there is no point in doing so. It is a triumph of marketing over reality.

P.S. -- I should make clear that I am not comparing a cassette with a stinky-slinky dump system. If that were the choice, I'd probably choose a cassette. Rather, I am comparing it with a modern, permanently-installed macerator dump. I have a slinky for emergency use, but have never had the pleasure of using it. Compared to a good macerator, I can see zero advantages to a cassette (given our travel patterns), unless one believes that they can get away with dumping in a McDonalds. And even then, there is still the grey tank.

Originally Posted by GeorgeRa

If cassette waste space is not vented to outside any pressure buildup can ultimately cause odor, just like a black tank if net vented. Vent doesn’t have to be powered.

Is it possible that your experience with odor was due to lack of venting?

Dunno. But it wasn't a low-end rig.

An unpowered vent cannot make up for a leaky seal--at least if the wind isn't blowing.

[GeorgeRa]

Originally Posted by avanti

I can assure you that no one in the world is more sensitive to odors than DW.

How could a properly functioning plumbed toilet smell? If it smells, it leaks. (there is a previous thread that describes a certain specific line of toilets that had some kind of design defect that creates an internal vapor leak. I don't consider such a system as "properly functioning").

I never said that most people don't use chemicals. I said the there is no point in doing so. It is a triumph of marketing over reality.

P.S. -- I should make clear that I am not comparing a cassette with a stinky-slinky dump system. If that were the choice, I'd probably choose a cassette. Rather, I am comparing it with a modern, permanently-installed macerator dump. I have a slinky for emergency use, but have never had the pleasure of using it. Compared to a good macerator, I can see zero advantages to a cassette (given our travel patterns), unless one believes that they can get away with dumping in a McDonalds. And even then, there is still the grey tank.

Dunno. But it wasn't a low-end rig.

An unpowered vent cannot make up for a leaky seal--at least if the wind isn't blowing.

Higher than ambient temperature of the black tank content will facilitate venting by stack effect. Aerobic digestion is exothermic, keeping the chimney effect going.

“Composting - Controlled decomposition of organic matter under aerobic conditions by which material is transformed to humic material. The process is exothermic resulting in a rise in temperature. The process is used to improve the quality of manure as organic fertilizer.”
Ch22.

Importance of oxygen for aerobic bacteria. Oxygen treatment will reduce odor when tank/cassette is open and during dumping for cassette. I learned these principles during my boating times, it is not just marketing scheme.

“Sewage contains both aerobic (needs oxygen) and anaerobic bacteria (functions in an airless environment); neither can function in the other’s environment. Why is that important? Because only the anaerobic bacteria in sewage produce foul-smelling gasses! Aerobic bacteria break sewage down, as does anaerobic bacteria—but aerobic bacteria do not generate odor”
https://www.raritaneng.com/blog/odor...holding-tanks/

[avanti]

Originally Posted by GeorgeRa

Oxygen treatment will reduce odor when tank/cassette is open and during dumping for cassette. I learned these principles during my boating times, it is not just marketing scheme.

I've already acknowledged the advantage during the 1-2 sec flush interval. That part isn't a marketing scheme, I suppose.
But, it just amazes me the percentage of the RV world who believe that smelly heads are normal.

[Davydd]

I currently have an 18 gallon black tank and dump about every two weeks on the road with a closed macerator hose so there is no clean up, smell potential or otherwise and not visible dealing of the waste. I timed it. It takes no more than 5 minutes to dump our black and grew water tanks at the same time from start to finish. Where I store my van at home I have this dump station (photo) a couple hundred feet from my garage which is convenient. No need to dump in a toilet. Black tanks are vented and there is no electrically powered exhaust vent required.

In my new van I could have had a cassette toilet in my design without a pull out hole visible in the van sides, but I opted for a macerating toilet. ARV is installing a 24 gallon black tank because it doesn't have to be under the toilet and can be in an optimum space under the van. I probably don't need it but there is a valve so you can equalize the black tank with another 24 gallon grey tank to extend a stay for a whopping 48 gallons. Odds are I will still dump sooner but anticipate going three weeks before dumping. I'm not sure which will rule yet because the fresh water tank is 38 gallons.

In my new van the toilet is placed almost in the middle of the van creating maybe one of the largest bathrooms in a Class B at 31" x 38". It's a 144" WB short Sprinter and I don't have to poop and pee in my living space and can shower easily inside with elbows out.

This is our condo garage dump station. The water was there because it rained the day before. That is not dumping waste water.

[GeorgeRa]

Originally Posted by Davydd

I currently have an 18 gallon black tank and dump about every two weeks on the road with a closed macerator hose so there is no clean up, smell potential or otherwise and not visible dealing of the waste. I timed it. It takes no more than 5 minutes to dump our black and grew water tanks at the same time from start to finish. Where I store my van at home I have this dump station (photo) a couple hundred feet from my garage which is convenient. No need to dump in a toilet. Black tanks are vented and there is no electrically powered exhaust vent required.

In my new van I could have had a cassette toilet in my design without a pull out hole visible in the van sides, but I opted for a macerating toilet. ARV is installing a 24 gallon black tank because it doesn't have to be under the toilet and can be in an optimum space under the van. I probably don't need it but there is a valve so you can equalize the black tank with another 24 gallon grey tank to extend a stay for a whopping 48 gallons. Odds are I will still dump sooner but anticipate going three weeks before dumping. I'm not sure which will rule yet because the fresh water tank is 38 gallons.

In my new van the toilet is placed almost in the middle of the van creating maybe one of the largest bathrooms in a Class B at 31" x 38". It's a 144" WB short Sprinter and I don't have to poop and pee in my living space and can shower easily inside with elbows out.

This is our condo garage dump station. The water was there because it rained the day before. That is not dumping waste water.

86 gal. tanks with variable weight of 720 lbs. of fresh/grey/black are likely a record for a 144” WB 2500 Sprinter van. Without road clearance reduction I was able to put 20 gal of fresh/grey/hot, with an additional 20-gal tank in lieu of a spare tire I could be at 40 gal.

Did ARV perform a magic of fluid compression or simply reduced road clearance by a few inches?

[InterBlog]

Originally Posted by Popcorn

Hello,

To me, it would make sense to use cassette toilets and tankless water heaters on Class B coaches. The grey and fresh tanks could be bigger and the bathroom location could be more flexible. Winter travel could be facilitated by placing a five gallon fresh tank inside the heated area of the coach and the cassette toilet would flush just fine using RV anti-freeze.

My $0.02 and worth every penny,

Bill

Getting back to the OP's original statements, no usage context was provided, so let me throw some in:

(1) It has been established on multiple threads that tankless water heaters are non-starters for boondocking because they require too high a water through-put to operate with limited Class B supply.

Campgrounds with hookups are a different equation, but many B owners shy away from campgrounds - that's why we have Bs, because we treat them more like regular vehicles, and many of us operate largely off-grid.

(2) Similar calculus regarding cassette toilets. One poster who is a confirmed cassette owner said above, "We normally dump at campground dump stations,..." That's great, but WE normally wouldn't be caught dead in a campground. We regard them as necessary evils, but spend 95% of our time boondocking. With limited access to inoffensive dump stations, a cassette is not something we would ever choose.

Especially given my history as a former cassette-type owner (portable Thetford with a detachable base that functions the same way). That thing was a nightmare, and its usage is something that I have no intention to ever repeat unless we are in a full-blown state of regional emergency and I have no alternative.

[booster]

I am not going to get into the whys and why nots things but I would just say that a cassette toilet "is not my cup of tea". Or probably more accurately "not my tank full of s..........tuff".

[avanti]

Originally Posted by InterBlog

(1) It has been established on multiple threads that tankless water heaters are non-starters for boondocking because they require too high a water through-put to operate with limited Class B supply.

Yes, this is true of conventional tankless water heaters that have their own combustion chambers--takes too long for everything to spin up.

BUT: it is not true of flash-plate tankless DHW heaters used in conjunction with a hydronic loop heater such as an Espar D5. Given the that the glycol is hot, these are truly instant, will give you unlimited hot water, and work at any flow rate. This is the approach used with th Rixen system and has many happy users including ARV.

[Davydd]

Originally Posted by GeorgeRa

86 gal. tanks with variable weight of 720 lbs. of fresh/grey/black are likely a record for a 144” WB 2500 Sprinter van. Without road clearance reduction I was able to put 20 gal of fresh/grey/hot, with an additional 20-gal tank in lieu of a spare tire I could be at 40 gal.

Did ARV perform a magic of fluid compression or simply reduced road clearance by a few inches?

The tanks are all forward of the back axle and a spare tire has no bearing on the tank placements. I currently have 86 gallons of tanks in my current ARV. Where a spare tire could go in my current van I have 800ah of lithium batteries under the floor. It is all RVIA and MB compliant. Balance, as you fill the grey and black tanks you empty the fresh tank. I don't take on more water until I empty my waste tanks but I could. Water and waste weights are covered in the maximum load carrying capacity of the van and don't count against the maximum weight delivered of 7,400 lbs. Maybe they know more than you George.

[GeorgeRa]

Originally Posted by InterBlog

Getting back to the OP's original statements, no usage context was provided, so let me throw some in:
…………………..
(2) Similar calculus regarding cassette toilets. One poster who is a confirmed cassette owner said above, "We normally dump at campground dump stations,..." That's great, but WE normally wouldn't be caught dead in a campground. We regard them as necessary evils, but spend 95% of our time boondocking. With limited access to inoffensive dump stations, a cassette is not something we would ever choose.
Especially given my history as a former cassette-type owner (portable Thetford with a detachable base that functions the same way). That thing was a nightmare, and its usage is something that I have no intention to ever repeat unless we are in a full-blown state of regional emergency and I have no alternative.

I am not sure I understand your post. Having experience in both porta potty and cassette I would view comparison similarly of comparing a Yugo to a Cadillac, both have 4 wheels as both have the same s…...

[GeorgeRa]

Originally Posted by Davydd

The tanks are all forward of the back axle and a spare tire has no bearing on the tank placements. I currently have 86 gallons of tanks in my current ARV. Where a spare tire could go in my current van I have 800ah of lithium batteries under the floor. It is all RVIA and MB compliant. Balance, as you fill the grey and black tanks you empty the fresh tank. I don't take on more water until I empty my waste tanks but I could. Water and waste weights are covered in the maximum load carrying capacity of the van and don't count against the maximum weight delivered of 7,400 lbs. Maybe they know more than you George.

I would certainly hope ARV knows more about conversion business than me, they are doing it for living. Looking forward to see road clearance on your finish van.

[GeorgeRa]

Originally Posted by booster

I am not going to get into the whys and why nots things but I would just say that a cassette toilet "is not my cup of tea". Or probably more accurately "not my tank full of s..........tuff".

Agree, not mine either, I like tea in a nice cup. All problems with cassettes, black tanks, or porta potties would vanish if we were designed/evolved to 100% digesting efficiency.

[MsNomer]

Originally Posted by GeorgeRa

I am not sure I understand your post. Having experience in both porta potty and cassette I would view comparison similarly of comparing a Yugo to a Cadillac, both have 4 wheels as both have the same s…...

George, having never owned either, I have always been curious. What is the difference—serious, not facetious, question from an ignoramus.