Fresh water level indicator woefully inaccurate

[NicandJay]

2020 MY Burstner td680g.. the fresh water tank level indicator on my control panel is woefully inaccurate to the tune of reading 25% full when pump runs dry. Van is level . Anyone know how I can get it at least a bit closer to being accurate as one may think ah... 25% remaining ...I have approx. 30 litres still on board... but no the tank runeth dry.
Any assistance greatly appreciated.

 

[autorouter]

Well... been inside water tank and up take pipes on floor of tank and it appears guage is governed by 5 metal probes of differing lengths that obviously create a circuit through the water in order to light the various markers on my control panel. 1 very short for 100% then 1 seemingly halfway down tank for 75% full.... well you get the picture well the remaining 3 are all almost the same length and sit almost at bottom of tank.

The gauge probes are cut to the correct length for each 25% step. Tanks shapes are very different, there are steps in the side and the floor, so that a simple depth measurement is often very inaccurate. If you can see the gauge probes while filling, does the 25% probe just touch the water surface when you put 25% of water into the tank?. If not, maybe you could trim it to fit. Or as you say get the dealer to do that.

 

[NicandJay]

Are they simply probes of solid or hollow metal ... no wires inside is what I'm really getting at.. guage reads 25% when water at bottom of pump but guess pump may also not be at lowest point of tank too and unfortunately no slack in wire or piping to get it down that far

 

[pappajohn]

If you get it 100%accurate it will be inaccurate again in weeks.
The grey tank even less.... Days or hours
Not even worth bothering with.
If the tap runs dry you're out of water.
If you get dirty water in the shower tray your grey tank is full.

Weather forecast..... Open your curtains on a morning... 100% accurate

 

[Ridgeway]

Ours is just as bad, 25% gradients and you can be at 49% when it says "quarter full" etc etc. I've looked over the years for an ultrasonic or optical solution as i believe that's the way to go, just haven't looked too hard..... i'm sure there's an off the shelf solution that can adapted from another application.

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[mitzimad]

yes just solid metal i adjusted mine with a pair of side cutters

 

[NicandJay]

yes just solid metal i adjusted mine with a pair of side cutters

Ah that's sounds promising... will look to see which of the longer ones touched water first and assume that is the 25% one and trim accordingly then work my way up or have I got that wrong? Question is why are there 5 probes but only 25, 50 75 and 100% markings on my gauge? Or can i trim any of the longer ones in any order to get somewhere close?

 

[autorouter]

Question is why are there 5 probes but only 25, 50 75 and 100% markings on my gauge? Or can i trim any of the longer ones in any order to get somewhere close?

One goes all the way to the bottom and is permanently in the water. When water touches the next longest, it bridges the gap and the circuit senses the drop in resistance. So the second longest is the 25% probe.

 

[NicandJay]

One goes all the way to the bottom and is permanently in the water. When water touches the next longest, it bridges the gap and the circuit senses the drop in resistance. So the second longest is the 25% probe.

Thanks Autorouter that confirms what I thought. I will check again in daylight and get the side cutters out....

 

[Lenny HB]

As it's a new van I wouldn't start pruning it as the probes do sometimes go faulty. Get a replacement under warranty and see how that goes.

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[NicandJay]

That is fair comment Lenny. Got to go back for replacement door due to manufacturing defect so it will add it to the list.

 

[ceejayt]

Ours is just as bad, 25% gradients and you can be at 49% when it says "quarter full" etc etc. I've looked over the years for an ultrasonic or optical solution as i believe that's the way to go, just haven't looked too hard..... i'm sure there's an off the shelf solution that can adapted from another application.

Expensive but boats and RVs in US have external sensors fitted. Nothing in the tank to get fouled up. I have just had a set fitted and will report back. Supposed to be accurate to within three eighths of an inch

 

[Ridgeway]

Expensive but boats and RVs in US have external sensors fitted. Nothing in the tank to get fouled up. I have just had a set fitted and will report back. Supposed to be accurate to within three eighths of an inch

I looked at a kit that is intended for oil tanks, the type that sit in your garden for your heating oil.

 

[Reallyretired]

Ah that's sounds promising... will look to see which of the longer ones touched water first and assume that is the 25% one and trim accordingly then work my way up or have I got that wrong? Question is why are there 5 probes but only 25, 50 75 and 100% markings on my gauge? Or can i trim any of the longer ones in any order to get somewhere close?

There will be 4 cathodes to measure and one anode so there should be two long ones, one is the 25% one the other is the common anode.
These things are never very accurate, but at least ours is in accurate the other way, says empty when there's quite a bit left.