Confused by leak

[Ridgeway]

Not hard really as most things confuse me.....

Here goes:

Van was regularly drained down for winter
Refilled 2wks ago, system bled, all checked and OK, fresh water tank was full
Truma valve opened last weekend, dropped the minimal amount
Brought van around to the house last week, reset the valve and topped it up until full

Off we went for a few days in the "sarf"

Tank ran down as expected, normal use, indicator worked as it should
Tried to refill and at approx 1/3 (roughly as I'm referring to the tank level indicator) water started to pour out from the underside of the van
Checked the Truma valve (just in case) but all OK
Checked all other drain points (just in case) but all OK
Thought that it was maybe just the level indicator and that the tank was indeed full
Decided to run the water down until i could hear the pump asking for more water and then i knew for sure it was empty, refilled about 30ltrs (100ltrs tank) and again water pouring out...

So my logic is that the leak can't be on the cold or hot water system as the pressure switch on the pump would cause the pump to continually run and that's not the case and that either A) the water tank itself has a leak at a certain height or B) the refill pipe is some howe leaking ?

What have i missed and is my logic reasonable ?

I need to bring the van back around to home at the weekend to dig into this but want to arm my brain with some likely scenarios and places to start the search....

I know how difficult it can be to find leaks so any ideas welcomed.

 

[Richard n Ann]

Sounds like the filling pipe has come off the tank

 

[gus-lopez]

Or you have a "travelling mode" with only 20 or 30L & you pull the lever to dump tank down to that amount. May be the valve is in wrong position?

 

[Jev88]

Dump valve broken?

 

[pappajohn]

Truma valve opened last weekend, dropped the minimal amount

Truma valve dumps the lot, not just a bit.
No point in draining some and leaving the rest to freeze.
Kind of defeats the object of the valve.

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[Lenny HB]

Or you have a "travelling mode" with only 20 or 30L & you pull the lever to dump tank down to that amount. May be the valve is in wrong position?

I would go with that, if it was the tank or a pipe it would flood the van. You need to look underneath and see where the water is coming from.

 

[Ridgeway]

OK so a quick mooch around yesterday:

- all connections looks OK
- dump valve closes and seals as it should
- main filling pipe connected and not loose
- no signs of any cracks or splits in the fresh water res

Will have to get the van on the drive at home and ask Mrs Ridgeway to pour some water on me whilst i'm underneath, that'll at least put a smile on her face

 

[Pausim]

I agree with the travelling mode opinions above. On both my Hymer and my current Carthago if you wind the cold water tank drain down wheel to the first stop it dumps most of the water but leaves 20 to 30 litres of travelling water. Wind the knob all the way back and you should get the full load.

 

[Ridgeway]

I agree with the travelling mode opinions above. On both my Hymer and my current Carthago if you wind the cold water tank drain down wheel to the first stop it dumps most of the water but leaves 20 to 30 litres of travelling water. Wind the knob all the way back and you should get the full load.

There are 2 "travel outlets" ie 25mm outlets with inline ball valves, both at different heights. Checked both and both seal correctly. Good thought though

 

[Ridgeway]

Leak found

After about an hour lying in puddles in the rain i could just see a very small jet of water (very fine) that's coming out of the fresh water tank The tank is a complex shape, sort of a smaller rectangle on top of a large one and the hole is on a 90º joint, a typical weak spot on MDPE tanks.

As removing the tank would be a major job i'm going to try to seal it in situ even if the leak is about 120cm inside the compartment and the access hatch is microscopic this is going to be fun.....

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[Lenny HB]

Before you start messing about see if you can get it plastic welded as it is about the only way to repair polypropylene. Most adhesives do not work on it and the ones that claim to often give poor results.

 

[Ridgeway]

Before you start messing about see if you can get it plastic welded as it is about the only way to repair polypropylene. Most adhesives do not work on it and the ones that claim to often give poor results.

That would mean removal unfortunately and that would be a big job as the nice Italian people that built the van decided it would be fun to seal it in the underslung box with more adhesives than Henkel factory so likely i'd need to rebuild it afterwards.

I'm pretty confident on the sealing as i've sealed 2 similar tanks before, both MDPE and i use an underwater sealant that sticks like the proverbial...

 

[Itsmcb]

CT1 ?

 

[Ridgeway]

CT1 ?

that’s a pretty good shout and I do have some here, I like it but for this I’ll use a polymer based sealant called Gold Label which cures under water and is good with all plastics I’ve used so far