Composting Toilet in Roadtrek Sprinter - Page 2

justme · 02-21-2021, 07:04 PM

We replaced our cassette toilet with an AirHead last fall. We mostly boondock and this change has extended our ability to do that until our drinking water runs out. With 2 of us we empty the liquids every other day or so. Since it is only liquid we can empty almost anywhere. We have yet to have to empty the solids since we have only been out for 2 weeks total since putting it in, due to work, winter, and COVID. The only issue for me is the height of the stool. I am ordering a folding foot rest to make it more comfortable. Otherwise I am thrilled with it.

ripaco · 02-21-2021, 11:24 PM

I have a 2004 Sprinter based LTV with a Thetford toilet that sits on top of the 10 gallon black water tank. I just finished a separating toilet with a urine diverter and 5 gallon bucket for solids. The toilet is 16" wide by 19" deep by 18-1/2" high including toilet seat. The back of the box is cut off at a 45 degree angle to allow clearance for the water valve and hose that go to the Thetford toilet. The bottom of the box is elevated 1" above the bottom of the outer box. The 80mm fan you see in the picture blows down through the elevated bottom so the air goes into the black water tank opening and up through the existing roof vent. The box bolts to the floor using existing 5/16" bolt holes in the tank flange. I am installing a standard SAE rainproof bulkhead fitting in the shower wall to plug the fan into. I can change either toilet to the other in about 5 minutes. To change, I remove the two hold-down bolts (5/16") and unplug the fan. Then set the Thetford over the studs and install the two nuts, screw on the water line, open the water valve and the changeover is complete. I also built a simple 18-1/2" square by 9" high platform that sits in the shower pan to bring the separating toilet height to a standard household comfort height. Total cost was < $200. We use the separating toilet for dry camping and the Thetford for "wet" camping.

engnrsrule · 02-24-2021, 10:51 PM

Finally had a nice enough day to crawl under and check things out. Good news! The hose was severed, the sheet metal splash guards bent up, and the reach rod for manually turning the pump was slightly bent. The cables controlling the black and gray tank gate valves were undamaged.

I was able to shorten the hose by 10" and reattach it to the pump, and then pumped down the tanks with no problem. Still need to straighten the splash guards and reattach a transverses support for the hose.

As for moving to a composting toilet, that is still on the table. I have submitted my needs to C-Head.

engnrsrule · 04-15-2021, 12:02 AM

While I still like the simplicity of the C-Head design, there are a couple of issues. They provide plans for building a "mock-up" to test your space. What I found is that the unit is too close for comfort. Potential interferences also with the odd shape of the rear wall and the water guard that is attached to the bottom of the door.

I may have watched every DIY video on YouTube about Composting toilets (or CT's). Many of these DIY jobs, while functional, are UGLY too and that won't do. The doohickeys folks come up with to separate urine are really quite remarkable. The automotive transmission oil funnel is a popular choice

. Also quite an array of churning systems are out there and I actually found one I like.

So here are my basic design elements:

Structure - The toilet base, sides and top will be made from PVC boards of various dimensions. The top will be radiused at the front to be slightly larger than the toilet seat, and the hole will be sized to fit a formed fiberglass one-piece urine diverter/poop chute, made in USA but modelled after designs popular in Europe, and will give a finished factory build look. It also has a nice steep drain arrangement. In a departure from every other design I saw, I am going to hinge the top at the front, and use lift-off hinges. This will improve my ability to make a watertight fit at the back, improve access for solids container removal when necessary, and allow easy removal of the top for deep cleaning as needed.

Urine Diversion to Black Tank - My Roadtrek has 10 gal black tank capacity. I expect we will get between 10 days and 2 weeks between pump outs, which represents a fourfold increase. The diverter has a long drop and will enter a pvc pipe, pass through a waterless trap, and go straight into the black tank via a bulkhead penetration fitting. The existing closet flange will be closed off with a flange cap and sealed. I may use the water supply line from the old Thetford and install a small line to rinse the diverter from time to time.

Solids Container and "Churning" - I will utilize a conventional 5 gallon plastic container. While I had considered purchasing the C-Head "innards" I found an innovative churning system from Frugal Factor on YouTube. In this system a bucket is first lined with a mesh bag, under which 2 lengths of parachute cord are strung, with one end of each leading to outside the toilet. A plastic garbage bag with the drying agent (peat moss, pet bedding, coconut fiber) is placed inside the mesh bag. After going #2, close the lid and pull the cords a few times - this tosses and mixes the contents in the plastic bag. Another advantage to this system is that when the bag gets full, just tie it off, lift it out and discard, and add another bag of fresh fiber media. You can even prepare plastic bags pre-loaded with fiber to simplify the process. You can see that the idea above of having the top hinged on the forward end will simplify the bag changing, and the whole process will be no more conspicuous to others than emptying the trash.

Ventilation - While I have not finalized this design, the plan is to mount a computer fan on the outboard side and run its output to the tank vent pipe that is adjacent to the toilet position. This pipe chase also has 12v power inside. I also have 6 other computer fans that serve interior and exterior circulation for the absorption fridge. In a pure boondocking mode I have a small Solar panel I can place on the dash and plug into a coach accessory receptacle to offset the small drain during the day. The exterior fridge fans are on a thermostatic control and don't normally run at night.

Watertightness - Since this is a wet bath I will be using some adhesive weatherstripping between the toilet seat and top, and as needed where the top meets the bottom and back wall. This will also facilitate ventilation air flow thru the unit for drying and odor control. I will make ventilation holes in an appropriate location so the air crosses the solids container.

The attached pictures show the C-Head Mockup adapted to open forward, and the fiberglass diverter. Comments and ideas are welcome

TygerMark · 04-15-2021, 11:33 AM

There can be great satisfaction with a DIY that really works.

But I decided that for me, retired with a new business making belt buckles and other accessories, only store-bought would do.

I could spend a week DIY toilet, or buy one that really looks good and- more importantly- works rhe way that it should,, and spend a day in the studio and pay for it.

Free Spirit Gear is the USA importer, but this Canadian source has better pics......

COMING SPRING 2021!! Separett Tiny Toilet 1271

https://canadianecoproducts.com/shop...y-toilet-1271/

BTW. What does anybody expect to accomplish by stirring? I never have understood that. You might toss a compost pile every month, but you NEVER work it every day.

engnrsrule · 04-15-2021, 01:53 PM

TygerMark,

I do like the Separett design, but like so many store-boughts, they are too big for the limited space I have (even the Tiny). Churning also ties to space. Non churning toilets generally require adding of material after use, that obviously must be handy to the user, and which shortens time between emptying. Churning coats the solids with material lessening odor and accelerating dehydration and shrinkage.

TygerMark · 04-15-2021, 02:44 PM

Double post....

TygerMark · 04-15-2021, 02:45 PM

Quote:

Originally Posted by engnrsrule

Churning coats the solids with material lessening odor and accelerating dehydration and shrinkage.

Not to be argumentative for sure, but I know composting. So, it follows that churning, moss, coir, etc is simply salesmanship and psychology when one is dealing with a small load of feces in an extremely short 3 or 4 week timeframe. The only true composting toilets are permanent installations that are about the size of a 35 gallon drum and larger

A ot of old wives tales out there circulate with fervor,, and are repeated over and over until they show up everwhere and long enough until they are generally accepted as true.

I have not seen one RV composting toilet "review" that was factual.

TygerMark · 04-15-2021, 02:54 PM

Let me just add that adding any organic material can improve the handling of fecal material.

But why handle it?

That is one of the main faults that find with of all of the toilets that have stirring mechanisms.

Separett toilets do not have a stirring mechanism because such a thing is absolutely unequivocally totally unnecessary.

engnrsrule · 04-15-2021, 03:01 PM

The paracord system eliminates "handling" as the churning all takes place within the bag, which can just be tied, lifted out and discarded (or moved to next phase of composting) like any non churning toilet.

I do understand that the term "composting toilet" is inaccurate. Separating toilets is more accurate.

TygerMark · 04-15-2021, 03:13 PM

Quote:

Originally Posted by engnrsrule

I do understand that the term "composting toilet" is inaccurate. Separating toilets is more accurate.

Yep.

Separating and desiccating is even more accurate.

Kudos to Separett for saying so.

For sure, in this day and age handling feces beyond snatching a bag and trashing it, or truly composting it, is something I just let others decide for themselves, as is their prerogative.

Why waste water resources and screw with a black tank?

Boondock forever, my man.

TygerMark · 04-15-2021, 03:17 PM

Speaking of boondock forever.

I can take on water from any good looking stream or lake. Fly over to make sure that there isn't a cow pasture within 1/2 mile upstream.

Then upload through 2 prefilters that go down to 1 micron.

On board, filter through 0.2 microns, then ozone treat.

engnrsrule · 04-27-2021, 10:41 PM

I have completed the construction of the base and am very happy with the results. I used 3/4" PVC and cut the sides and front as one piece. The sides start out rectangular and then transition to an arc that is longer on the top in order to given the front a more conical shape rather than a box or straight tube.

To achieve the curve I used a kerf cutting calculator. This is surprisingly strong and gives a very smooth appearance.

I have the fan roughed in and the urine diverter running to the black tank. More to follow.