Dometic Toilet Problem

Thetford are not without problems, including the one where it starts flushing spontaneously!  Much debated over the years on SwiftTalk.

In the case of the Thetford it seems to be a problem with the control board getting damp.  We have suffered from it and in the end I resorted  to fitting an additional button on the top of the tank, which interrupts the power, so now both it and the flush button have to be pressed simultaneously.

100% successful.

Well, hopefully, with our new one not having an internal flush tank, that shouldn't be a problem!

Hi Richard,

                   We are about to buy a van with a Dometic toilet and was interested to see you have actually swapped over to a Thetford, which is what I’d like to do but wasn’t sure if it was possible, may I ask who swapped yours over please?

Regards

AlannBailey

Having read the issues on the German made Dometic cassette, it would seem that my problem is nothing to moan about. "Ive mislaid the dump cap on my cassette, probably fallen down the hole. To get a replacement it will cost me £37.10. which would have made "Dick Turpin" blush.

Another vote for Thetford. My Dometic toilet is flimsy and hard to operate requiring regular silicone grease/spray to keep it useable. My old van with a Thetford had no such issues and was much more robust - no pretty colours tho’ 

Hi Alann

Sorry - only just seen this after the thread was resurrected.  The work was done by ALV at Tebay - the dealer from which we bought the Knaus. It turned out to be quite an easy job - it looks fine and, touch wood, we haven't had any problems since it was installed. As someone said earlier, it was the one thing that was spoiling an otherwise perfect van and I'm pleased I made the decision to shell out the extra cash and get it sorted once and for all.

We have a Dometic toilet in Our 2018 Coachman 520 VIP. The toilet cassette cracked on the underside after about 3 uses and within one year of purchasing the caravan brand new in 2018. We informed the dealer who contacted Dometic who said that I had damaged the cassette as it had some scuffing on the underside of the cassette. To cut a long story short this has been ongoing for well over a year with the dealer saying that they had informed me that Dometic had refused to replace under warranty, I don’t recall receiving any such notification, and me contacting Dometic directly. They reaffirmed their decision that it was not covered under warranty as there was some scuffing on the underside of the cassette so it was damaged by me. This turned into rather an irate phone call and raised a couple of questions.notably I asked who is responsible for consequential damage and they informed me that it would be me as it is now a known problem so I should replace the cassette but Dometic also made me feel as though mine was the only cassette that had failed in this way. On mentioning this on a Coachman forum I found that numerous others had had similar problems. Since I now cannot use the toilet unless I replace the cassette does this make the whole caravan not fit for purpose? Given that Coachman have gone back to using Thetford toilets I’m surprised that Coachman haven't done a recall and replaced this pile of junk that they insisted on using in their flagship van. Another problem that has developed is that the plastic film cover to the flush button has also holed. I am now waiting again to see what the dealer comes back with but am not holding my breath and considering going to trading standards as the cassette is not fit for purpose making the whole caravan not fit for purpose. I would advise anyone thinking of buying a caravan to avoid any with Dometic products fitted

Unlike the Thetford, the Dometic cassette is actually made of a much thinner, brittle plastic. I actually found a YouTube video of how to repair a crack in the Dometic cassette which made me think that it wasn’t an uncommon problem.

Another thing that sort of amused me - anyone found a way of emptying the cassette and holding the vent button down at the same time - without using three hands!😂

Given my previous comments, I can’t think of one single design feature of this toilet that is worth a recommendation.

I agree wholeheartedly with the comments about the Dometic loo. After a frustrating couple of years I recently changed mine for a Thetford C220 series unit. The changeover was relatively easy although i did have a problem with height tolerances on the Thetford loo between the casssette and the fixed part of the unit. To their credit Thetford did get back to me with some advice but in the end I’ve had to pack the cassette bottom rail by 3.5mm. Its no big deal and it would be an exaggeration to say its a pleasure to use and to empty it but I’m sure you know what I mean.

This is an old post, but for the sake of others, I would like to share my experience.

First of all, in the absence of a manual, I more or less dismantled the toilet (Dometic CTW4050). Probably a mistake.

The water filler for the flush must be removed from outside the van. It has a pipe with O-ring extending into the flush tank. You can then lift the unit off the internal wall plate (hook) that retains it.

Find the 6 long screws securing it to the floor of the van, and remove them, not the 6 screws that hold the damn thing together. You should be able then to lift it off, unplugging the supply first, and extracting the breather hose that presumably goes through the floor.

The flush water pipe is relatively heavy and ours has become stiff. Where it entered the outer bowl, there is a 90 degree elbow made of flimsy plastic that had deteriorated and literally crumbled. This is what was leaking. You need to remove the seat (lever up with thin blade at each of the triangular marks on the seat) to reveal the screws holding the 'flush ring'. You should then be able to remove the bowl (sealed in to the base), and gain access to this fitting. Nasty spring steel clips are used to retain the hose, awkward to release by easing the spring with pliers. They also rust. There is no support for the hose or wiring - suggest self adhesive anchors and cable ties.

The other end of the flush pipe on the tank goes into another naff fitting, which again broke. This also includes the anti syphon valve. Our tank was heavily polluted with black residue presumably from leaving pink fluid in the tank for too long. Some people say don't use it. The valve was presumably not working due to residue. Incidentally, the pump motor wires pass through a hole in this fitting, so that if the tank is overfilled it will spurt out of this, possibly over the electronic control unit?

I attach a photo showing the remains of the elbow, and the tank cap with syphon..