The Thetford toilet: a virtual tour and fixing it for good

[ShrimpBurrito]

My vinyl skirt was acting up again, so I decided to spend a little bit more time to find a solution. I called Thetford, and of course, the customer service rep had never heard of the problem. So they all must live in a vacuum.

But I did end up reaching an engineer there, and while that conversation was not all that I had hoped, progress was made.

First, the toilet is made from polypropylene. The only adhesive they could find that would work on it is 3M's Scotch-Weld Structural Plastic Adhesive DP-8005. He said it worked good, but not great. The stuff is also not cheap.

Second, as expected, the skirt's sole purpose is to prevent splash back of waste into the bowl while traveling. It does nothing to reduce odor. So if you have vinyl skirt issues and never travel with the toilet charged, remove the skirt with confidence and flush away.

Third, amazingly, he also had not heard of flushing problems. I told him that while a new vinyl skirt reduced the problem, it did not eliminate it, and that within 9 months or so of one weekend/month use, the new skirt had stiffened to the point where we were back to square one. According to him, that DEFINITELY should not happen. After 12 years, yes, but certainly not after 6-12 months. Contrary to what I have previously heard from Thetford customer service reps, as well as what other forum members have reported being told, he said there is no reason that the skirt should require regular replacement.

When I told him I was using Thetford's own AquaKem, he speculated that one possible reason for what is happening is that perhaps their purchasing dept had sourced a new vinyl skirt supplier, unbeknownst to the engineering dept, and the new supplier's skirt is not up to their original specs. But again, that is only speculation. So he is sending me a new skirt, and I am going to send him my old skirt, with pleasure, for analysis.

He also said that the toilet is made solely in Europe, and primarily sold there as well. But some are obviously exported to the U.S. Apparently there had been some discussion in their Europe office about designing some sort of flap or door to replace the skirt, but they could not justify the cost of retooling the molds and added manufacturing costs. He didn't know any details, but was going to contact them to try to get more information. So apparently they have heard of flushing problems in Europe!

I'll post an update whenever I hear anything more.

Dave

[ShrimpBurrito]

Working a bit more on the toilet as time allows....it's sorta developed into a challenge for me.

I pulled the top off to replace the vinyl skirt, and got a demonstration of the #1 point I made in my first post in this thread. Toilet paper goes OUTSIDE the steel mesh cone, and then cannot make it back INSIDE to be drained. Don't worry folks, it's just brown toilet paper.....any identifiable solid is disintegrated and flushed....but obviously there is residual.

AND -- I identified another design flaw with the Thetford. The bottom of the holding tank is flat, so inevitably, some of the liquid will not drain. This problem is exacerbated when the ground at the dump station has even the slightest tilt. If the TM is tilted just a bit in either direction, which is impossible to avoid, and there will be waste that slides to one side and will never reach the hole. Notice the bit of water in the center of the cone -- that's why you cannot see the white valve clearly. I dumped at a large commercial campground with a very well maintained and paved dump station. Nothing out of the ordinary.

The bottom of the tank needs to be slightly cone shaped, with the drain being the lowest point.

Dave

[ShrimpBurrito]

The vinyl skirt is history. I have started redesigning the toilet.

Tired of giving solids a motivational push down the toilet chute as they were being stopped by the vinyl skirt, I removed it. However, since the Thetford engineer told me that the purpose of the skirt was to prevent waste from splashing back into the bowl during travel, I wanted to put something in its place. I got a cheap piece of vinyl floor covering from Osh (local hardware store) that had a shiny slick surface on one side. I punctured a few holes on one end large enough for a zip tie to go through, and fastened it to the chute with the shiny side facing up towards the chute. I later trimmed the vinyl to be just a bit larger (maybe 1") than the hole of the chute, but I forgot to take a picture after I did that.

We took it out camping this past weekend and I am happy to report success!! Solids go down the chute like an Olympic luge athlete. It's AMAZING! Even better is that, despite coming down a 1-mile dirt road with diagonal speed bumps so large that I thought my Toyota Sequoia would bottom out, waste from the FULL toilet did not splash back into the bowl. I had put plastic wrap over the toilet during this test, and it was completely dry when we got to the dump station about 15 miles down the highway.

Total cost: about $2. Way less expensive than Thetford's $30 vinyl skirt (w/shipping), and hopefully, way more useful.

Dave

[Bill]

Dave -

This is a great piece of work you are doing.

How on earth does TP get outside the filter cone? I had my toilet apart a month ago, and it didn't look anything like your first picture. Yechhh!

The replacement of the vinyl skirt with the vinyl floor covering sounds like a winner. It is now on my "let's do it" list. I try never to travel with anything in the toilet, so the splash is of no concern to me. The other issue, however, is a definite concern. Did you lube up the shiny side with any silicone (etc) spray?

Thanks for your work, and your reports.

Bill

[ShrimpBurrito]

Bill,

Glad you like the idea.

I have no idea how TP ends up on the wrong side the cone. It appeared to me at first that the cone was tightly sandwiched between the bottom of the bowl and the bottom of the tank, but maybe it's actually not a tight fit. So when traveling down the road, the cone jumps up when you hit a bump, and some TP slides underneath. That's that only thing I can think of.

No spray on the new vinyl flap. With the water flushing against it, it is plenty slick enough.

Be sure you get some extra vinyl flooring so you can experiment. There needs to be holes in the vinyl not just on the top of the chute, but also one on each of the sides. The zip ties then thread through these holes (I made 4). How far the holes are down on the side of the chute is directly proportional to how much "give" the flap has in opening. The further the hole is downwards, the less give. You may not be able to see very well in the picture, but it looks like my zip tie hole on the side was about 1/3 of the way down. This was my first try, so I'm going to use it on a few more trips before I settle on this hole position.

Dave

Dave, you realize that you are the list expert on sh, err solid waste! I would have thought the partial function of the skirt was to guide waste into the cone, but apparently that is not the case. Keep up the posts, you could probably consolidate this thread and sell it as this would be invaluable info for anyone with a Thetford problem.

In re-reading this thread, I just had an idea. If the sole purpose of the controversial vinyl skirt is to prevent splashes while traveling, why not just get a piece of the floor covering you used and cut it to size so it just lays in the toilet bowl, covering the opening to the tank? This would stop splashes from getting out and if it did get dirty it could be easily cleaned.

[ShrimpBurrito]

Originally Posted by Scott O

If the sole purpose of the controversial vinyl skirt is to prevent splashes while traveling, why not just get a piece of the floor covering you used and cut it to size so it just lays in the toilet bowl, covering the opening to the tank?

Scott - I don't quite understand. Do you mean put a piece of vinyl in the bowl over the hole? If you did that, that would also prevent waste from going down the chute.

Originally Posted by thewitzclan

In my opinion and 1 year experience so far was to remove the thetford piece of junk and replace it with a regular fresh water rv toilet. It uses very little water and produces NO stink. There is no need for the noisy pump either. We are thrilled with it. My neighbors even praised the transformation. I tapped into the cold water line under the bathroom sink and we use a tote for the waste removal. Very easy and clean. The waste is directly dropped into the tote. The thetford is no more than a bucket with a screen/motor and chemicals to mask the stink of the pile of stuff that is growing in the bottom of it as you can see. We love our 3023 but the toilet was a nightmare from the beginning!!!!!!

While I agree the Electra Magic leaves much to be desired, and that it has many design flaws, I thus far have no had problems with odors. I like the concept of the recirculating toilet and the advantages it provides, but I'd like to attempt to refine the Thetford before taking a more radical approach.

If I could even find another recirculating toilet for sale, I would try it, but thus far, I have not found any. And probably for good reason. These things don't sell very well, perhaps because of the aforementioned design flaws. Best I can tell, while most of Electra Magic sales are in Europe, TM buys about half those sold in the US. That's not very much volume.

Dave

[ShrimpBurrito]

As suspected, I confirmed that the steel cone does not fit snugly in between the underside of the bowl and the bottom of the tank. I had to repair the seals in the EZ Slide valve (after only 18 months of doing it before), and after I removed the valve from the bottom of the toilet, keeping the toilet upside down, I lowered the camera into the waste discharge hole and took this picture. As you can see, the cone is a good inch off the bottom of the toilet. That means there is adequate play such that the cone can bounce up and down while going down the road, allowing TP to migrate outside the cone.

The reason I mentioned in a separate thread that the "whooshing" may not be required is that obviously some solids move outside the cone along with the TP. However, I did not find any solids mixed with the TP found outside the cone. I think the solids get liquified adequately to pass through the cone.

I'm thinking about attaching some weights to the cone to prevent it from bouncing off the bottom of the toilet.

Dave

[mcgyver210]

Originally Posted by ShrimpBurrito

Scott - I don't quite understand. Do you mean put a piece of vinyl in the bowl over the hole? If you did that, that would also prevent waste from going down the chute.

I think what he was saying is put it there for travel only & remove it when camping. Actually that sounds like a decent idea in away if that is what he meant. Shouldn't be that nasty if toilet is clean for travel & not to be gross waste wouldn't get stuck before going down.

The reason I mentioned in a separate thread that the "whooshing" may not be required is that obviously some solids move outside the cone along with the TP. However, I did not find any solids mixed with the TP found outside the cone. I think the solids get liquified adequately to pass through the cone.

So does this mean the Sewer Solution isn't causing it not to clean like it does with the Whooshing of 3" Hose. I have experimented with both & honestly so far haven't seen the Whoosing make much difference for actual clean out.

Sorry I missed your question Dave, thanks Billy for picking up on it. Yes, I did mean leaving the plastic in the bowl only when travelling. The vinyl skirt would probably be superior, but when it stops working I'm not going to replace it.

And I agree with you Billy, I don't really know if the full 3" flow really helps in dumping. It just seems to me the water pressure allowed by a large hose would help move the heavy stuff. I use the 3" in camp and clean/rinse out as best I can there, then add a couple of gallons of water to slosh around on the way home. Then I use the Sewer Solution to again clean the tank out at home. Without taking the Thetford apart there is really no way for me to know if this works...and I'm not about to get into that!