Toilet Talk

[Paullus1959]

**WARNING** As the title indicates this post is about toilets and their use. I don’t want to start a debate on who uses their toilet for what functions or whether they use it at all. This is about a recent experience and the conclusion I’ve reached.
We use our toilet and shower for that matter, because we often stay on sites that don’t have toilets and showers, our choice.
So, the point is that during our current holiday near York in the caravan the mechanism on the Thetford C260 toilet cassette completely failed and a part fell inside the cassette. After a thorough cleaning I removed the mechanism from the cassette and retrieved the broken part, the black component in the top of the picture with two dome headed screws shown, hoping to be able to reattach it. However, the four screw mounting attachments had completely snapped off and were beyond repair. This meant that the circular sealing flap wouldn’t close which presented problems when taking the cassette to be emptied but, fortunately it wasn’t full so no unpleasant spillages occurred.
I found many compatible replacements online costing around £45 but preferred to get a genuine Thetford one which online cost around £65 or a whopping £85 in stock at a place 45 miles away. For another £40 I could get a Thetford Fresh-up kit with a complete cassette and toilet seat. As this was an emergency with a week of the holiday to go, I decided to go for a mechanism costing £45.99 with next day Amazon Prime delivery to the site we’re staying at.
It arrived early the following morning and I carefully examined it. I couldn’t find any discernable difference between the old and new parts. The new one even had the same part numbers in the same place on the main component and the slide. It was quite stiff in operation so, I carefully slackened the retaining screw on the flap mechanism with the white nylon washer under it, which freed the mechanism up just enough. I then the gave the seals a liberal spray with seal lubricant and refitted it into the cassette, it fitted perfectly and I’ve now got a fully functional loo again thankfully.
I then took a look at the broken mechanism before binning it and came to conclusion that I’d been using the toilet incorrectly. I have read discussions on toilet use, specifically if they should be used with the flap open or closed. I always used it flap closed, my wife didn’t agree. However, she’s right, the loo should always be used with the flap valve open as the structure that supports the valve flap is not designed or intended to bear any weight at all which is why the one in my cassette eventually snapped off, albeit after six years.
So, the cheaper replacement cassette mechanisms do fit and work correctly and the toilet should always be used with the flap open.

 

[otherclive]

I wouldn’t even consider using it with the flap shut as it doesn’t stay clean, although some place a sheet of toilet paper to prevent stuff sticking to the flap.

 

[Banus]

Whilst emptying my cassette (C250/260) the slidey / flappy door (as shown in your left image) slid off the top of the cassette and disappeared down the drain together all the waste. We were on holiday at the time but fortunately it didn't stop us using the toilet. I enquired about a replacement and was told that I'd have to buy the entire mechanism from Thetford costing £50. Surely not. Amazon came to the rescue at £5.99. I now remove it (slide it off) before pointing the waste tube down the hole. I nearly didn't bother replacing it as I'm not sure what purpose it performs.

 

[Paullus1959]

I wouldn’t even consider using it with the flap shut as it doesn’t stay clean, although some place a sheet of toilet paper to prevent stuff sticking to the flap.

I‘ve always used tissue and even tried those Happy Bowl liners to protect the flap and the need to clean it. Thetford say it doesn’t matter if the flap is open or closed but, clearly it does from my recent experience. From now on, it’s flap open

 

[Jcloughie]

Point taken Paulus. However, we have always used our loos, various Thetfords, and one Dometic, with the flap closed, but we always leave a little flush water in the bottom. This is for three reasons. One to check that the seal is working over a period of time, two to provide an additional water seal, and three to keep things clean when in use,

Never had a cleanliness issue. But I think the mechanisms differed to yours.


John

 

[Dustydog]

I have to disagree.
Even Thetford say only use the toilet with the flap open. Using closed causes a number of issues.
1. The plastic flap seals on its top not bottom side.
2. The plastic flaps are a weak point .Using closed can stress the flap.Note the weak plastic cog mechanism.
3. Using shut and then opening! Watch the splash back and of course the need to wipe the proverbial Klingons off the flap🤮
Please yourselves. In our caravan the flap is open when in use!

 

[otherclive]

Using with an open flap allows the content level to be gauged for when the red “full” decides to not work.

 

[Jcloughie]

I have to disagree.
Even Thetford say only use the toilet with the flap open. Using closed causes a number of issues.
1. The plastic flap seals on its top not bottom side.
2. The plastic flaps are a weak point .Using closed can stress the flap.Note the weak plastic cog mechanism.
3. Using shut and then opening! Watch the splash back and of course the need to wipe the proverbial Klingons off the flap🤮
Please yourselves. In our caravan the flap is open when in use!

As I said, the problem may be model-specific. Certainly, not all Thetford instructions say to only be used open. The ones I have had, including a Senator, say this.


I would be interested to see where Thetford say it can cause problems.

There should not be a splash back if the pressure equalisation valve is operating correctly.

I also suggested leaving water on the blade as a seal and continuous test. I would still do that, but Thetford advises against it saying it does not improve the seal, (well water seals have been, and continue to be used domestically with great success).

They also say it can lead to flooding, that would have to be explained to me, it makes no sense. But hey ho.

John

 

[Buckman]

The only time you may get an issue is on a very warm day and the cassette has been emptied recently. On opening the flap the pressure inside may cause blow back. Not pleasant.

 

[JTQ]

Leaving flush water or whatever in the bowl means you have 100% faith in the main seal working.
For something, when camping pulled in and out most days or every few days depending on your usage style, needs way more confidence in that design than I have.
Our is always used open, and always kept open in storage. To me, it seems logical not to 100% depend on the seal functioning completely as intended, life rarely "pans out" that way.

 

[Jcloughie]

Leaving flush water or whatever in the bowl means you have 100% faith in the main seal working.
For something, when camping pulled in and out most days or every few days depending on your usage style, needs way more confidence in that design than I have.
Our is always used open, and always kept open in storage. To me, it seems logical not to 100% depend on the seal functioning completely as intended, life rarely "pans out" that way.

Only about 5mm of flush water is left in. The worst that can happen is a little damp on the top of the tank. I would see this as a warning that maintenance is required. But as I kept up my maintenance, the issue never arrived.

John

 

[Dustydog]

Only about 5mm of flush water is left in. The worst that can happen is a little damp on the top of the tank. I would see this as a warning that maintenance is required. But as I kept up my maintenance, the issue never arrived.

John

John
Why leave 5mm of flush water in ? I really don’t see the technical advantage🤔

 

[Jcloughie]

John
Why leave 5mm of flush water in ? I really don’t see the technical advantage🤔

As said previously, it creates a water seal as your home toilet. It continually proves the seal is good, it helps with the cleanliness. (Klingons, I think it was you who used that term).

Not major advantages, just fits my logic and has served me for 38 years of caravaning.

John

 

[JTQ]

As said previously, it creates a water seal as your home toilet

Though far from the same, the home WC has a water trap, where a pressure head greater than that water head would be needed for the soil pipe gases to break through. In that case it serves a positive important function.
Whereas, water standing above a seal in our van toilets forms no trap at all, bubbles of vapour from the cassette simply would rise through that, it's the nature of things to do so. Plus, if as said the units well maintained, the cassette vent would have balanced the pressure.

Any seal leakage would not cause "damp" on the cassette top, it's made of impervious plastic, it would form a puddle till big enough to roll off into the bottom of the cassette's enclosure.