Dometic toilet flush
Hello
I have recently purchaded an LMC 695 with a dometic WC (selling my beloved winnebago in the process, something which I may live to regret maybe) but anyway I digress, this van has an onboard water tank, when I push the button to flush the WC I can hear the pump pulse under the sofa where the tank is, however it doesnt flush any water through to the WC at all, and yet the bathroom tap which is literally 500mm away from the WC runs smoothly when you open it, the water is from the same tank and pump I assume ? is there an isolator somewhere in the pipework to the WC that simply needs opening ? there is no seperate filler on the outside of the van above the cassette opening which would lead me to believe that it had its own supply tank, so I assume that it is from the water tank under the sofa..................this is probably a complete D'oh moment and I am simply missing a trick here.............can anybody please help as this has me totally stumped..............first ever caravan so lets to get my head around as it is, thanks in advance.
Andy.
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Hi swift reply as I need to do dinner not play on here!
Don't know you're van but I know some vans have separate toilet flush tank fill, somewhere outside with a water entry? Our motorhome flush comes direct from fresh water supply.
Good luck.
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We had our useless Dometic toilet in our Knaus, changed for a Thetford - for a host of reasons which I have previously outlined on here.
In the process, the flush water was changed from coming from the header tank to being drawn from the inboard tank. It didn't work properly to start with, with identical symptoms to yours.
It turned out that the feeder pipe had become squashed as it passed through some ducting from the tank to the WC. That white water pipe is very soft and easily distorted so it might be worth checking to see if the same has happened to yours.
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Hiya
Thanks for your help, the cassette has been flushed to ensure that the float that detects the fluid level is not clagged up with stuff (pardon the explantion) this apparently can cause the WC not to flush as it thinks it is 'full' because non of the 'led's' light up to signify the level inside the cassette..........the toilet doesnt have a header tank / cistern of its own it is flushed from the onboard tank.
I know what you mean about the white pipe being soft and therefore could be squashed.............at this point that would probably require removing the entire WC to inspect it ..............so the upshot is that I am a big believer in getting the right person in with the right experience / skills / tools.................so we have a guy coming over next Friday............sub contract the problem so to speak :-) and the pay the bill accordingly...........as it would appear that the nearest approved repairer is a days round trip away along with the diesel required to get us there...................so a day off work with no pay and diesel to boot, so its gotta be more economical to get a man in !
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"I know what you mean about the white pipe being soft and therefore could be squashed.............at this point that would probably require removing the entire WC to inspect it"
In our case, the pipe was led through a wooden 'duct' through which the air hose for the Truma heating also passed into the bathroom. It was simply a question of removing two screws which held the top in place and fiddling about with the hose to release the trapped bit. It was a two minute job - so it might not be as bad as you think.
However, since you are getting someone to look at it - I would strongly recommend asking the cost of replacing the Dometic with a Thetford and since you already have a feed from your inboard tank, it should be very easy. Based on my experience of Dometic toilets, I suspect your current problem is just the start of many!
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Hello
Just in case anybody is remotely curious as to the eventual diagnosis .............the soft white pipe wasnt trapped, the solenoid was opening correctly, however the WC bowl has a flush ring under the rim of the bowl, this flush ring has a float type arrangement which under pressure of the water entering moves upwards to allow the water through, it is then supposed to drop back down (under its own weight/gravity) and then close to prevent any backwards flow.........similar to a check valve/non-return valve, however due to the weight of the plastic bung/float and the tightness of the rubber seal to the inside of said valve it sticks up or down dependant upon where you have phsically put it, so seeing as the WC was never used it was in the downward position and the water pressure was insufficient to move it upwards, so basically we have pushed it into the upwards position and are relying on the solenoid to be the non-return valve................ da dah !
And as for the question of what I am towing it with, I am using a transit custom combi, which is basically my back up work van/car, and it tows a dream, you dont even know its attached other then the road surface fluctuations (potholes etc)
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and I appreciate your opinion of simply swapping it for a thetford, however having now taken it to bits along with the caravan engineer (seeing as it was a new model WC it was one that he wasnt familiar with) the van is only 9 months old and I am led to believe that the WC is a new model one .............it seems pretty simple, somewhat crude in its simplicity to be honest .............so we will plod on with for the meantime, but thanks for your opinion.
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Sounds like it tows well, and I have no idea of the spec of the vehicle, but are you aware of the rules for body length of caravan in relation to tow vehicle?
I remember this discussion.........
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Just so that ww can open your link, Kjell I've made it live.
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Talking about toilets, I heard somewhere that to clean limescale from a Thetford tank use Cola. Have just flushed the tank with clean water after it had been soaking with Cola for a few days . Magical, the tank is totally free of limescale it's like new. I used 1 Sainsburys bottle of cola at 45p highly recommended.
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This post spurred me on to replace our totally useless Dometic cassette loo. As others have said the faults with these are legion including a trap that seizes up after the second use and has to be sprayed with lubricant after every action. A holding tank that is heavy enough even when empty, is ergonomically very poor when trying to empty it and a reverse flow valve that also restricts the forward flow rate significantly. My frustration was complete when the holding tank level gauge float fell off last weekend. In short it has been the only thorn in our otherwise perfect Burstner Ixeo motorhome. The replacement Thetford unit arrived today so I’ll keep you posted re the removal of the old and installation of the new in due course.
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As promised, here’s an update on the removal and replacement of the Dometic cassette loo with a Thetford C223S unit in our Burstner iXeo motorhome. Removal of the Dometic loo, including the controller, took about 15 minutes tops. The Thetford unit is slightly lower than the Dometic one so I had to make a bulkhead adaptor that fits between the old bulkhead and the new loo. I used 10mm MDF with a wood finish very similar to the existing one. The water supply pipe from the onboard tank fitted into the Thetford pipe without difficulty and the electrical connections were simple enough, albeit it took a little time to work out the cable core colour coding since neither the Thetford installation instructions nor the Dometic ones identified the core colours. The new unit is so much more user friendly than the Dometic loo and the whole process of changing the units over took about 4 hours in total. I’d definitely recommend it.
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