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Old 04-24-2014, 03:34 PM   #1
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Vacuum Toilet information needed

Hi guys,

I'd like some help installing a vacuum toilet into a converted cargo trailer (converted into a toy hauler). There's no room under the floor for a gravity toilet system and we worry about foreign matter destroying a macerator pump. Also I hear vacuum systems use much less water so I decided on building one.

So here's the system setup order...

RV Toilet>duckbill>Hose to top of tank(4ft)>vacuum sensor>2duckbills>diaphram pump>2 duckbills>exit to holding tank.

*Note duckbill after RV toilet is to prevent waste from shooting out of the ball valve if someone leaves it open too long

*the vacuum sensor is to turn on and off the diaphragm pump, if it detects pressure it engages

*the diaphram pump is like this... http://www.amazon.com/Johnson-Pump-V...s=viking+power
it's designed to lift upto 10ft then push the waste out.
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Old 04-24-2014, 05:37 PM   #2
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There's no room under the floor for a gravity toilet system and we worry about foreign matter destroying a macerator pump.

The joy of an RV gravity setup, is there is almost ZERO to brake or maintain.

Build/raise the floor and find a thin 8 inch holding tank and enjoy not chasing with mysterious air leaks and night time pump noises.

No macerator pump is required and the gravity 3 or 4 inch dump at most campgrounds takes a Very! short time.

The trick is Educating boat designers about the joys of a no effort RV setup.

There is NO system that uses less flush water or that is 1/10 as reliable ,

NO GRAVITY is pretty rare!
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Old 04-24-2014, 06:36 PM   #3
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Why reinvent the wheel, just buy a SeaLand VacuFlush. Or better yet, take a look at Tecma heads.

If you're going to build you're own vacuum system I'd pass on the Johnson pump and get one by SeaLand. Better pump in my opinion.

Vacuum heads hold vacuum at the toilet bowl. Can you're RV bowl do that?
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Old 04-24-2014, 07:38 PM   #4
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Why reinvent the wheel, just buy a SeaLand VacuFlush. Or better yet, take a look at Tecma heads.

If you're going to build you're own vacuum system I'd pass on the Johnson pump and get one by SeaLand. Better pump in my opinion.

Vacuum heads hold vacuum at the toilet bowl. Can you're RV bowl do that?
This trailer is for semi-public use, there could be 50 people using it in a day for several weekends during the summer months and vacuum toilets seem like the ideal solution in terms of allowing the occasional foreign object through and the use of less water.


Tecma is a Macerator toilet.

I looked up Sealand's patent on their vacuum toilet, it's seems to be only for the mechanism which opens the valve, not the toilet. I believe the toilet is an RV toilet with an actuator on it, it also could have some higher quality seals around the ball valve too... If I'm wrong RV Toilets are cheap.

We're thinking about using it in a setup similar to some yachts and commercial grade designs... it's similar to this...


My system would look like this...


Once the waste has past the top elbow it's all down hill from there.
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Old 04-24-2014, 07:51 PM   #5
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The joy of an RV gravity setup, is there is almost ZERO to brake or maintain...
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... take a look at Tecma heads....
RV stuff for what you want to do. Tecma may have what you want. Look at their Cassette Series.

Cassette C-200 CW/S/CS
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Old 04-24-2014, 08:29 PM   #6
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another picture of how marine system works
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Old 04-24-2014, 08:56 PM   #7
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The cassette doesn't have a big enough holding tank for 50 people.

You may have to add a vacuum tank inline to hold enough vacuum for the head to work properly.

And vacuum toilets use more water than you might think in order to properly move the crap down and out the lines.
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Old 04-24-2014, 09:28 PM   #8
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I do understand the tank is used so that there's "extra" vacuum in the lines so it doesn't dissipate so quickly, as shown in my diagram that's addressed by adding a pipe & Y fitting with a pressure sensor at the top, this pipe can be a larger diameter or longer to make the vacuum last longer.

I also had another idea of using a straw into the waste tank so the vacuum in the pipes could suck the waste out of the tank up to a point so when the toilet is opened the holding tank water is dropped back down assisting the waste from the toilet to continue moving however this system requires that water always be present in the holding tank to prevent air from entering in from that direction.
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Old 04-24-2014, 09:31 PM   #9
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Can also line the bowl of the toilet with superhydrophobic material so it takes even less water to clean the toilet bowl.
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Old 04-24-2014, 10:21 PM   #10
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Hmmm... If the pipe off the Y holds a lot of the vacuum will some of the poop travel into it? And if so it would seem to be a place that would not get flushed out well with water. Just guessing here.

Can't say what good coating the bowl would do as far as saving water. In that you need a fair amount of water to keep the lines clean. Even SeaLand acknowledges that. In fact it's good to flush the toilet with just clean water in it from time to time to keep stuff from hanging up in the lines and valves.

The straw idea seems like an over complication to me.
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Old 04-25-2014, 06:53 AM   #11
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> Can't say what good coating the bowl would do as far as saving water.<

PAM is the bowl lubricant of choice for the RV toilets that use almost no water.

>Vacuum heads hold vacuum at the toilet bowl. Can you're RV bowl do that?<

No need to, the seal simply holds water from dropping straight down into the tank from the pull of gravity.

The diameter of the RV hole is about 2 or 2 1/2 inches , so stuff drops with little to no added water.
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Old 04-25-2014, 09:47 AM   #12
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>Vacuum heads hold vacuum at the toilet bowl. Can you're RV bowl do that?<

No need to, the seal simply holds water from dropping straight down into the tank from the pull of gravity.
My point was there would be a need if you are going to use an RV toilet on a vacuum system. In the system the OP is talking about putting together there would be no gravity drop on the other side of the seal. But there would be a vacuum.

On a SeaLand vacuum toilet for example there is vacuum right on the other side of the bowl seal. If the seal leaks the water in the bowl goes down and then the vacuum pump starts coming on from time to time to make up the vacuum loss.

That is why I asked if the RV toilet he is considering using can hold a vacuum seal. They may be able to but I personally don't know that to be true or not.

I can see how Pam would work in the bowl. But I can't see how it would do much good helping the stuff move down the hoses and through the duck bills after it's left the bowl. Without gravity to help, I don't see how you can get around using perhaps more water than you would like or hope to to make that happen.
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Old 04-25-2014, 12:42 PM   #13
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Luckily I actually have an trailer with an RV Toilet to test this sucker out.... What I am going to do is pull vacuum on the holding tank and test to see if the water in the RV gets sucked out. I can pull 20hg if needed but I'll just need to do halve that.

Another very important question is if these systems can stand having a tampon applicator or other foreign object thrown in. If the pump doesn't like it then I'll have to come up with something else.
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Old 04-25-2014, 06:43 PM   #14
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Another very important question is if these systems can stand having a tampon applicator or other foreign object thrown in. If the pump doesn't like it then I'll have to come up with something else.
A tampon perhaps . The applicator? You'd have to check with SeaLand on that. With enough water in the system perhaps.

There are marine heads out there that are more forgiving of something like that. Headhunters come to mind. But they use a fair amount of water and I'm not sure how well they would work without at least some slope to the holding tank.

I take it there is absolutely no way possible to mount a holding tank just under the trailer, even if it was shallow but large in it's other dimensions?
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Old 04-25-2014, 11:37 PM   #15
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Luckily I actually have an trailer with an RV Toilet to test this sucker out.... What I am going to do is pull vacuum on the holding tank and test to see if the water in the RV gets sucked out. I can pull 20hg if needed but I'll just need to do halve that.

Another very important question is if these systems can stand having a tampon applicator or other foreign object thrown in. If the pump doesn't like it then I'll have to come up with something else.
be very careful trying this.. all you may accomplish is to collapse the holding tank... square tanks are not really designed to pull a vacuum...
look at the vacuum tank on a vacuflush..

If you want a vacuflush just buy a vacuflush

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Old 04-26-2014, 07:14 AM   #16
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>My point was there would be a need if you are going to use an RV toilet on a vacuum system.<

MY point was to raise the floor to install a holding tank under an RV toilet,

save a grand or two in parts and pieces and energy and trouble shooting and ongoing maint..

Anyone in SW Fl that wants a FREE toilet set up to be sucked dry , come and get it!

Just the toilet , the rest of the nightmare system you will have to assemble.
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Old 04-26-2014, 07:36 AM   #17
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[QUOTE=FF;229990
MY point was to raise the floor to install a holding tank under an RV toilet,

save a grand or two in parts and pieces and energy and trouble shooting and ongoing maint..

[/QUOTE]

That would be the best way to go. Especially with the OPs concerns about clogging. Either way it's got to be a good sized tank to accommodate 50 people a day filling it.
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Old 04-26-2014, 04:15 PM   #18
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>Either way it's got to be a good sized tank to accommodate 50 people a day filling it.<

If its just guys dumping the belly tank after renting some beer or coffee , a 50 cup tank is hardly huge.

If an army of visitors is using the vehicle as a latrine , the Std RV system of a maceriator hooked to the dump valve and 1 inch hose will usually pump 100ft or so to where ever it will be dumped .
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