david lloyd Posted May 14, 2016 Share Posted May 14, 2016 Hi everyone, just back from a very pleasant week away. Still getting used to the Fiat based Chausson Welcome 717GA but loving the additional space over our previous PVC's. However, we had noticed a significant difference in the frequency with which the Thetford C250 toilet cassette needs emptying - particularly compared to the 400 series bench cassettes we have been used to. So, as an experiment, I have filled the cassette with a measured amount of water. After just ten litres the red light came on. As, I believe, the capacity should be 17 litres, I took it out of the locker and put another full 5 litres in. It was just nearing the full mark then. I know that Thetford say when the red light comes on there is still capacity for another couple of uses (but how long is a piece of string?) or around 2 litres of liquid but this seems to indicate that the holding tank is only two thirds full when the light comes on. Anyone else had this problem and can it be solved by adjusting the float? David Link to comment Share on other sites More sharing options...
Tracker Posted May 14, 2016 Share Posted May 14, 2016 Welcome back to the world of 'proper' motorhomes David - we too reverted last year, albeit to a rather compact coachbuilt, and have absolutely no regrets whatsoever! I have never taken any notice of the red light as all it takes is a quick look down t'ole and you can see when it is full! Experience quickly tells you how far you can go and if you get it too full and a spill occurs you don't do that twice! Bear in mind the more you put in the heavier it is and that is an issue for some but you can experiment at home with plain water to find a level you are happy with. Somehow it always seems heavier with the real stuff in it than it is when full of just plain water!! We're lucky - ours is a bench type and they do hold more - but all the capacities are on the Thetford website if you need to know! Link to comment Share on other sites More sharing options...
Brambles Posted May 15, 2016 Share Posted May 15, 2016 I would check the position of the reed switch which detects the magnet/float in the casssette. Just checked mine and is a hole about 1.5 inches lower it could have been screwed to so maybe there are optional positions for the reed switch assembly. Sits on the left upper area as you look in the cassette locker. Link to comment Share on other sites More sharing options...
Brambles Posted May 15, 2016 Share Posted May 15, 2016 Tracker - 2016-05-14 3:36 PM Welcome back to the world of 'proper' motorhomes David - we too reverted last year, albeit to a rather compact coachbuilt, and have absolutely no regrets whatsoever! I have never taken any notice of the red light as all it takes is a quick look down t'ole and you can see when it is full! Experience quickly tells you how far you can go and if you get it too full and a spill occurs you don't do that twice! Bear in mind the more you put in the heavier it is and that is an issue for some but you can experiment at home with plain water to find a level you are happy with. Somehow it always seems heavier with the real stuff in it than it is when full of just plain water!! We're lucky - ours is a bench type and they do hold more - but all the capacities are on the Thetford website if you need to know! Only once have I had to unscrew the empty spout cap and drain excess into a container -- agree - will only ever be that once but actually was quite easy to to so. The time I got really upset was when someone used the loo while I was off emptying the cassette, the assumption on their part being as long as they did not open the valve!!! He was only 8 at the time. Link to comment Share on other sites More sharing options...
david lloyd Posted May 15, 2016 Author Share Posted May 15, 2016 Brambles - 2016-05-15 2:38 PM I would check the position of the reed switch which detects the magnet/float in the casssette. Just checked mine and is a hole about 1.5 inches lower it could have been screwed to so maybe there are optional positions for the reed switch assembly. Sits on the left upper area as you look in the cassette locker. That was sound advice Brambles so I dashed out to check. There is no sign of a switch on the side of the locker - except for the flush switch and that is connected to the water pipes. I should also explain that the toilet does not have a built in plastic back in the bathroom but the flush switch and red indicator light are on a small,panel which is set into a wood panel behind the toilet. However, looking into the cassette locker, right at the front curved area, is a plastic cover held in place by two screws. Behind this is more wiring and a small pcb with a square block wired in that must be the reed switch. If it is then it is located approximately two inches lower than the roof of the cassette holder top (where the blade would sit immediately beneath the toilet bowl) and would, therefore, activate at the level I found it was at when only ten litres of water was added. Unfortunately, it does not look like it can be moved upwards as it is set into moulded in clips right at the top of this inner removeable panel. David Link to comment Share on other sites More sharing options...
Derek Uzzell Posted May 15, 2016 Share Posted May 15, 2016 A large Thetford ‘repair instructions’ document can be downloaded from here: http://www.rosefacchini.co.uk/upload/Sanitation%20Repair%20instructions.pdf This file includes details of the C250 model’s reed switch. Link to comment Share on other sites More sharing options...
Brambles Posted May 15, 2016 Share Posted May 15, 2016 Ahhhh! I see the arrangement now for the level switch which is quite different from mine and I suspect you previous van. Thanks for the link Derek. It look like it operates by the float magnet moving up and away from the switch which if so would mean if the cassette is removed the light would come on. Sounds as annoying as my fresh water tank which displays empty when I still have a 3rd of a tank left. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted May 16, 2016 Share Posted May 16, 2016 Thetford introduced the C250 range so that leisure-vehicle manufacturers could provide a ‘customised’ cassette toilet. The thinking was that a basic less-expensive C250 could be chosen for, say, an entry-level motorhome, while a C250 with more bells and whistles could be fitted to a de-luxe motorhome where price was not so critical. A C250 could be obtained with enhancements that included a multi-level indicator of the cassette contents. The control-panel carried three LEDs, with the lower LED indicating that the cassette was almost empty, the middle LED indicating that the cassette was more than half full and the uppermost LED illuminating when the cassette was near full and could take only 2-3 further uses. The same 17.5 litres-capacity cassette is used for all C250 toilets, so the difference between the simple cassette contents-level indicator and the multi-level version lies elsewhere. The multi-level indicator has a different control-panel and a different reed-switch is fitted. Assuming that David’s C250’s control-panel is the basic version with the single cassette contents-level warning LED, the fact that only some 12-13 litres of liquid are needed to trigger the warning LED suggests the possibility that a ‘multi-level indicator’ reed-switch is present and that the single LED is lighting up on the intermediate setting. Pure speculation, but the scenario fits... Link to comment Share on other sites More sharing options...
david lloyd Posted May 16, 2016 Author Share Posted May 16, 2016 Thank you Derek. Yes, the (separate) control panel does only have a single red warning light and, as I originally posted, this illuminates fully when just ten litres of water are in the cassette so quite a bit less than the 17.5 litre capacity. Looking at the positioning of the switch (if it is indeed behind the panel located at the front curved section of the cassette housing) it does not seem likely that a simple modification can be made to allow a more meaningful reading. David Link to comment Share on other sites More sharing options...
Derek Uzzell Posted May 17, 2016 Share Posted May 17, 2016 Pictures of the various C250 reed switches and its housing can be viewed here: http://www.bradtech.ltd.uk/products/Reed-Switch-C250-One-Switch-T50713.html#SID=105 http://www.bradtech.ltd.uk/products/Reed-Switch---C250---Single-Level-T50714.html#SID=105 http://www.bradtech.ltd.uk/products/Reed-Switch---C250---Multi-Level-T50715.html#SID=105 http://www.bradtech.ltd.uk/products/Reed-Switch-Housing---C250-T50716.html#SID=105#SID=105 The switch plugs into a housing ‘stem’ and (based on the photos in Thetford’s Sanitation Repair Instructions I gave a link to earlier) should be easily located within the cassette locker and visually apparent. It might be worth checking the operation of the float inside the cassette (instructions on earlier link). The plastic swinging float is simply clipped in place and there’s no obvious means of adjusting the height of its travel. It’s be known for the float to become completely detached (usually due to the cassette being violently shaken during the emptying procedure) but the float in your cassette is clearly doing something to turn the warning light on. If the float were swinging properly it’s not easy to understand how it could produce a too-early warning that the cassette is full, which suggests that the problem lies with the reed switch. Link to comment Share on other sites More sharing options...
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