Post project writeups, ideas, DIY mods and off the shelf modifications and improvements. Also "Known Issues" and their resolutions.
January 17th, 2018, 6:56 pm
Hi All Chinook Peeps! And a happy new year! I have a curious question. Has anyone replaced their existing toilet with a composting toilet? My husband did a quick inspection of how the toilet was bolted in, and sees nothing. Is swapping it out even an option? BTW, we made it cross country from Vermont to Arizona...thru the first east coast snow storm, and the prairie cross winds, without any problems...knock on wood! That was all back in December. We have to (sob) head back east the first week of February, and all we have heard is how sub zero it is back home. What goes up, must come down, I guess.
Thanks for any input all of you wise ones! Michele & Norman (and Vinnie, the camper van)
January 19th, 2018, 10:43 am
A couple of things:
First of all, the conventional toilet that comes in the Chinook is mounted to a flange/pipe. Reason is that this pipe is what leads to the holding tank. Also, the toilet would not be secured to the floor otherwise and would tip over.
But a "composting" toilet (I put that in quotes because these don't really compost in RV's but they do "dry," which is enough) doesn't connect to any holding tank. It just sits on a flat floor. Then you secure it just so it doesn't roll around. So it's of no particular meaning that it doesn't fit the tube/flange.
I have no particular beef against them (used an outhouse for years, which is similar), but I'm not sure I'd put one in a Chinook. Why do I say that? Well, the Chinook has a 15 gallon black holding tank already. So that would be going to waste (I think it would be hard to re-purpose that tank for grey water as it sits above the grey water tank so plumbing might be complicated). So now you'd have a pee jug to dump somewhere every couple of days, when before you could go longer by using the black tank. (Granted you could go longer before dumping the dried solids, but you still have to dump the pee jug every day or two.) I'm starting to notice large "pee dumps" around the periphery of some sites (they smell and in the desert last a LONG time), so that's something to consider (going on a hopefully longer walk with the pee jug to dump it, or maybe digging a hole).
I do see the value in these toilets in rigs that don't have a black water setup already, but the way the Chinook is built originally the tanks are a breeze to dump (and you can go longer between dumps vs. the pee jug on a composting toilet). There is one way I did think of. This was on a friend's Class C that had a really stupid setup with an angled (!?) tube leading from the toilet to the black tank, and unless you used TONS of water to flush, the #2 would get left behind in the tube and the whole works would clog. I thought that a drying type toilet would work well there if you used it for #2, but diverted the pee (only) to the holding tank. That way you'd have the best of both worlds (no pee jug to dump every day or so). We don't need that though as our tube runs straight down as it should.
Beyond all that (if you are still with me here), I think there would be another issue that might make one of these toilets an issue in a Chinook, and that is that they are generally a bit tall, and the Chinook toilet already sits up on a platform. So a composting toilet would be REALLY high off the floor. C-head makes one that is supposed to sit partially on a platform, so that might work (haven't checked dimensions).
I suppose if you weren't going to be using the black tank anyway, you could cut out the floor of the shower room (I think the black tank sits under the raised area in the molding which makes the toilet platform), remove the black tank, and then re-fiberglass a flat(ter) floor. That would be a big job, and I don't see the gain, myself.
So..... I'm curious: What is your motivation for installing one? Maybe your holding tank setup is broken somehow? Or you don't find 15 gallons adequate to go between dump stations anyway? Or?
January 19th, 2018, 3:16 pm
I am also curious to know why would you want to get a compost toilet if you already have a working plumbing for the black tank. It is an alternative for a small campers such as Toyota Chinook and 1970 VW minibus, but I don't see the advantage in this case.
February 11th, 2018, 10:05 am
Thank you for your response—and Blue Go, I really appreciate your Chinook expertise!
So our reason for considering a composting toilet, is that removes the need for water, and concern for the holding tank freezing. We use this RV for a trek across country during the winter, so following the advice of others, we have winterized it, and have been staying at year round campgrounds with shower houses. Even though the rig is winter-ized, it would be nice to be able to use the toilet during those times where we don’t want to get up in the middle of the night, and schlepp to the bath house. And not worry if the tank heater is working or if we are adding enough antifreeze along with our ‘stuff’. As I type this, we are on our way back to Vermont, and holed up near Ketchum, OK during the Mateo mess—which has made the roads covered with ice here (we are now thinking about putting studded tires on at least one pair of the duel tires for next year’s trek). I know some of the small camper vans use a Thetford toilet which is basically a porta potty, but the composting toilets work differently, as you had mentioned, keeping part 1 & 2 separate. There was an interesting post by a young couple that live in a (BIG) bus and put a Nature’s head in their rig. But as you said, they are very tall, and given the platform in the Chinook, that the toilet currently sits on (I did not realize this was the holding tank!!—but my husband did know), you would need a latter to get on the darn thing. Anyway—-just thinking of ways to tailor to our use of it.
February 11th, 2018, 11:25 am
Knowing your thought process adds another dimension to it. I do think a composting toilet in a Chinook is probably not a great idea. Anything is doable, but.... it's always harder to put a square peg in a round hole. But maybe there is another way for your to reach your goal of being able to use your own facilities in cold weather.
You may already have thought about all this and know it won't work for some reason, but.... have you considered winterizing the supply lines but not the waste system in cold-but-not-ridiculously-cold weather? It's not that the black/grey tanks won't freeze, but they won't freeze nearly as soon as the supply system, in my experience. The lines are bigger (1-1/2" or larger, as compared to 1/2" or smaller) for starters. I would say in the waste system the two areas of concern would be the traps and the dump valves. If the dump valves freeze, they seem to thaw without lasting damage (I'm sure it's possible to damage them, but I've known many people who have had them frozen, then later dumped and had no future trouble). Traps could possibly be replaced with something like a Hepvo trap which doesn't require any water (uses a membrane). And of course the toilet basically has no trap.
So what I'm picturing is that you winterize the supply system and use jugs of water at the sink and the toilet (since the toilet is just a hole, you can just flush it by pouring some water in manually). As I'm sure you know, it's completely possible to heat a rig while not attached to shore power as long as you aren't using electricity to do so (looking at you, electric tank heaters....).
Not sure a composting toilet would work very well in below freezing conditions either, so even though your traditional system would not be working 100% normally (i.e. you'd be pouring water in to flush vs. letting it come in via the supply lines that run behind the shower), the composting toilet might not be working 100% either.
As I think about it, if I were going to be traveling in cold weather a lot, I might install a valve (easy with PEX plumbing - basically tinker toys) that would allow me to winterize the supply plumbing just after the kitchen sink. So in other words you could have the water tank, pump, kitchen sink (and even water heater, or not) in use; but NOT have the lines that go back behind the shower to the toilet, bathroom sink, shower, and outdoor shower in play. If you either open the door under the ouch, or perhaps add vented openings to it (or replace it with a more porous door), then the remaining plumbing would get more of your interior heat. Likewise isolating the shower trap (Hepvo, add antifreeze between showers, or isolate it somehow).
Just some ideas. You may already have thought of them and discounted them for some reason.
February 12th, 2018, 9:34 am
The salt in the urine and other dissolved solid in feces will depress the freezing point of the content in the black tank. I have not experiment with how does the salt work in RV, but it is what my high school chemistry text book says. There are some lake in Antarctica that never freeze due to the high salt content, for example. I don't think you can freeze urine completely, since there will always be some liquid left... I would try it myself by putting a bottle of urine in a labelled bottle outside and see what happens, but it is not cold enough to freeze anything here.
February 12th, 2018, 10:44 am
I'll admit I'm conservative and so if it's going to get below around 25º I have drained my waste tanks and put a bit of antifreeze down the hatch (to rest against the dump valves). But that said, I have friends who regularly camp in low to mid-20's overnight lows and don't do a thing with the waste tanks. What seems to happen is that the dump valve freezes shut (which you would only notice if you tried to dump just at that moment), but then thaw again with no damage. I know that seems counterintuitive, and maybe would not always be the case, but maybe they aren't damaged because they "wipe" most of the liquid away from themselves with the blade action they have, and/or because the liquid in the tanks has room to expand (and as mentioned above, probably doesn't freeze as readily as plain water).
I would really, really like to put a Hepvo trap on the shower. For one thing, it tends to siphon itself empty when I drive (it's barely above the grey tank), and two, it hangs out completely outside the coach and I would NOT like to have that one freeze, because it's quite inaccessible to repair. A Hepvo would solve all three of those issues.
Of course for the same reason (inaccessibility) I haven't yet put in a Hepvo trap -- I think I'd have to drop the grey tank to get to it. OTOH, it wouldn't be too tough to put one on the bathroom sink and the kitchen sink. But, I don't tend to use the bathroom sink (I prefer the wide-open spaces of the kitchen), so I just leave antifreeze in that trap year 'round; and the kitchen one gets heat from the interior pretty easily.
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