Hymer fresh water tank

[mikejkay]

My Hymer Exsis-t 414 has a shallow storage compartment beneath the garage floor. Last year I used this compartment to store food when travelling through Scandinavia. When I came to access this food, which required completely emptying the garage, I found that it was wet and that there was a significant amount of water in the compartment. 8-) . Several inches deep in the corner. I thought at first that some bottles of Tonic Water had leaked but the bottles were still full and the water was fresh. I bailed the water out and continued my travels. On my return to the UK I found that the compartment had filled up to the extent that it was overflowing and flooding the garage.

 

Cue a 420m round trip to Travelworld who checked for leaks and decided that the source of the water was the fresh water tank via the seals for the access hatches. After some trials and tribulations I have just had the two caps in question replaced, a second 420m round trip :-( . On leaving Travelworld I was informed that the reason for the leaks in the first place was that I drove with a full tank of water. Apparently I should only drive with 20% water. I am aware that the manual stipulates this but I had thought that this was because of fuel economy and weight restrictions.

 

In the past I have owned a Pilote, a Swift, a Chausson and a Hobby. With none of my previous motorhomes have I come across this restriction nor have I every had any sort of water leak.

 

Surely, to design a water storage system that can only be used at 20% of its claimed capacity negates the whole point of a motorhome. Difficult to find potable fresh water in the mountains of Norway and the forests of Finland!

 

Do others have leaks such as those I have described? Do others drive with full water tanks? How many of you restrict yourselves tp a 20% fill up? How do you know when you've reached 20% when filling, the gauge is not at all reliable!

 

I am at a loss. Do I continue with my travel habits? risking water damage. Or, do I cart 25 litre containers full of water?

 

This all smacks of the recent controversy about the sale of motorhomes with miniscule payloads >:-(

 

P.S. I have drilled a hole in the base of the compartment. :-D

[Thai Bry]

Hello Mike

This may not be the answer to your problem.

We have always travelled with around 20 to 30 % fresh water on board.

This gives us enough for our immmediate useage.

We then fill up when nearer a place that we plan on staying at of even on stellplatz if using municipal sites.

[Mickt]

When in France going from aire to aire i always travel with full tank, i know 100 ltr is heavy but water is not always available

[Brock]

On the top of the fresh water tank in my Hymer, there is a grey triangular knurl which I can turn to limit the water to 20 litres. It's reliable enough. When set, any more than 20 litres floods out from the tank and out of the vehicle - not into the underfloor compartments or garage. I travel with more than 20 litres usually but from memory, never more than 100 litres. I change the water in the fresh water tank at least every four days so 100 litres is more than enough.

 

The only time I fill the fresh water tank is when I clean it. Once I discovered that if the blue cap is not screwed down correctly, water will seep out of the top - I suppose it would pour out if I forgot to put the cap back on! I know that the flow of water into the tank from a tap must be less than the overflow from the tank otherwise something will give as the water fills the tank. I have the tap at home on just quarter a turn. It is easy to overfill the tank because, as you say, the gauges are not that accurate.

 

I've answered your questions as much as I can from my experience. You could try Highbridge Caravans, who are Hymer dealers, and nearer to Torbay for your future Hymer needs.

[snail]

Hi, when our Hymer was new we had a fresh water leak, it was from the large screw tops, one for cleaning and one with pump in it, these had excess plastic from when tank was made that just needed trimming off to allow the screw on lids to seal correctly no problem since in 11 years, always travel full

 

Snail

[StuartO]

About 10 years ago Hymer started quoting water capacity based on travelling with 20 litres of water (maybe since altered to 20%) and I always assumed this was to boost the claimed payload. Prior to that some models were said to have restricted water capacity (mine is below 75%) and again I assumed this was to limit the weight on the tank. Hymer do not explain their restrictions but I cannot imagine that it would be because the tank would leak!  I wouldn't swallow Travel World's explanation without clear confirmation from Hymer. 

I always travel with at least 50% and often 75%, occasionally 100% and have never suffered any leaks. 

[Brian Kirby]

Our Exsis-I 578 was driven with a full tank from new, reducing as we travelled until the tank was indicating 50%, at which point I'd refill it. I filled to the point at which I could see the water against the top of the tank, which was a while after the gauge hit 100%. There was no sign of leakage during the 4 years / 25,000 miles we owned it. We drove on all manner or roads, with all kinds of gradients, up and down Alpine hairpin bends, and no water escaped past either the fill cap or the underfloor access cap.

 

Our van also had that strange sump under the "garage" floor and it remained dry throughout (I know this because I checked it several times :-)).

 

I'd suggest filling the tank and driving it a bit more, and then checking for signs of leakage, and then, if you find leakage, reducing this to the travelling" 20 litres and driving it some more, preferably up and down a few twisting hills. That will test Travelworld's theory as to cause. The pump/water level gauge mounting points are alternative potential leakage points. Obviously, if there is no further leakage the fault lay with the access cap. I agree that it may be worth looking at the cap seating to see if there is a bit of casting flash preventing the cover from seating properly. The caps do need to be tightened firmly to ensure the seal is compressed.

 

With a full tank there is little opportunity for water to surge around on braking, accelerating, hills, bends etc., but 20 litres in a flat, wide, 100 litre tank will be surging around no end. I can't verify this, but I'd guess those surging 20 litres would give all seals other than the access cap (which on ours was more or less central) a much harder time than when the tank was full.

[flicka]

I think Travelworld must think their customers where born yesterday & they need to get better informed about the products they sell.

If Hymer fitted a water tank that MUST not exceed 20% capacity, common sense dictates they would fit a smaller (& hence cheaper) tank, which would also release additional space for alternative use.

 

Logically, there may be an outlet which enables users to drain down the tank of water in excess of the "20%" for travel purposes & if this is not closed it could be the sourse.

BUT any water draining off would NOT be released into the vehicle interior.

Therefore something is wrong.

Missing vent tube ?

Insecure or damaged water pipework ?

Leaking tank ?

 

 

[Derek Uzzell]

As Brian has said, the large-diameter access caps commonly fitted to motorhome water tanks (example in attached photo) do need to be firmly tightened - and a DIY-made tool may be required to undo the cap if it has been tightly screwed in.

 

If the significant amount of water in the storage area of Mike’s Hymer got there by leaking through the tank’s access caps, it’s likely that water would have collected on the tank’s top around the caps. If water had been evident on the tank’s top, Travelworld’s diagnosis was (probably) correct and (hopefully) replacing the caps will have cured the problem. But - as flicka has pointed out - there are alternative explanations for water leakage, and the only realistic way to check whether replacing the access caps has successfully addressed the problem will be to seal up the newly-drilled hole in the base of the compartment and drive with a full water tank to see if the the compartment stays dry.

 

This MHFacts thread refers to a 2016 Hymer Exsis-t model and the water-tank drain.

 

http://forums.motorhomefacts.com/60-hymer-motorhomes/200522-hymer-fresh-water-tank-drain.html

 

The tank ‘partial’ drain-down valve allows Hymer to specify their motorhomes' Mass-In-Running-Order (MIRO) weight with an allowance for just 20 litres of water, but it definitely does not compel the motorhome’s owner to drive the vehicle with its water-tank part-empty.

 

Nowadays many motorhome manufacturers adopt a similar strategy, with some quoting MIRO with zero allowance for fresh-water. My Rapido 640F’s fresh-water tank’s capacity (in litres) is specified as 120/20, with a ‘footnote' advising that the tank can be filled up to 120 litres but doing this will reduce the payload. As Rapido provide no means of draining the tank to the magic 20-litres figure, it might be assumed they believe nobody will bother. ;-)

[keninpalamos]

I have two of those access screw fit caps on my tank which I use to clean and de scale the tank plus the fitting for the pump. Common sence must prevail here and not some dealers bull. They should be water tight. ie they should not leak under any circumstances. That means even when the tank is full of water which is what it is designed for. ie it is designed to hold water in a vehicle. Poor construction is not an excuse. When is the motorhome industry going to understand their customers, the people that pay their wages, us, are not idiots. I’ll tell you when. When we stop excepting some of the crap they are turning out. End of rant.

[mikejkay]

I presume that when Travelworld replaced my caps they would have spotted such excess plastic and remedied the problem, even if theysaid nowt to me >:-( . However, I will check. Can to be a bit more specificc? Is the excess on the tank or on the caps?

[mikejkay]

It's probably 20 litres. I just remember the 20 bit. Why bother to put in a large tank if it is unusable?

[mikejkay]

Well, thanks for all the comments. They have settled my mind somewhat. The consensus seems to be that the 20 litres figure is stated in order to achieve a higher payload. Hopefully the new caps will eliminate the leak but I will be keeping an eye on them. Just in case I will only be stowing items that will be unaffected by water in the underfloor compartment.

[Brian Kirby]

I think dry everything out, remove the false floor panel in the garage, fill the tank to the brim, and then take the van for a run over hilly, twisting roads. Stop as and where you can along the route to see if water is accumulating in the garage sump. If you see water, drain off the tank to eliminate further leakage.

 

Also, check your Hymer manual. :-) Page 28 of ours states, under "Terms", "Mass in ready to drive condition", that mass in ready to drive condition includes the basic equipment weight which, in turn, includes the water system filled to 90% (tank and pipes). It goes on to say "Example for calculating the basic equipment weight: Water tank with 100L - 100kg. Our Exsis tank was max 100L capacity, so that would be full.

 

See also the section on calculating payload, where it advises weighing the van with full tanks in order to establish actual payload.

 

Only in section 10.2, water tank, does it state that the tank contents must be reduced to 20L for safety and regulatory reasons. This is a clear contradiction of the earlier advice on weighing the van at a weighbridge with a full tank. It seems Hymer need to clarify what is the actual safety risk of driving with a full tank, and which part of which regulations actually require this.

[lennyhb]

Our last van was an Exsis i678, only had the problem once after a drive over some twisty rough roads.

It is a known problem I believe Hymer have redesigned the water cap on the tank.

Only tends to happen if you overfill the tank. Also need to make sure the cap is extremely tight as the water moving about will loosen the cap on twisty roads. On the Exsis it is very easy to overfill it as it is only a small 100 Lt tank that is very shallow and after 100% reading on the gauge easy to get another 15 Lt + in which is when your problems occur. Not helped by the tank being mounted behind the rear axle it gets bounced about a lot more than if it was in the centre of the van.

 

If you make sure the cap is very tight & don't fill past 100% on the gauge it should be fine, On our Exsis we always used to carry 2 x 20 Lt containers of water in the garage because of the small tank. Thank goodness the new van has a 160 Lt tank.

[mikejkay]

Brian

 

Thanks for the interesting snippets. I must confess that I hadn't read sufficiently deeply and found the bit about calculating the allowable mass. I have, however, measured the total weight several times and even with full fuel tanks, full water tanks, an electric bike on a towball mounted rack plus a garage stuffed full of food, tools, bottle jack etc I have always been well under 3,500kg. :-D

 

Perhaps a query to Hymer is in order to get clarification.

 

 

 

[snowie]

Hi Mike, I use a Gardena watersmart gauge on my hose, works a treat. About £15-20.

Can’t comment on the 20% capacity issue, other than how devious manufacturers can be in pursuit of a meaningful payload,

Regards

Snowie

[Derek Uzzell]

This link is to an English-language Hymer 2011 ‘generic’ instruction manual

 

http://ourbumble.com/wp-content/uploads/2016/01/Hymer-B590-Manual.pdf

 

On Page 146 (as Brian has mentioned) there is the following advice

 

"Water tank

The water tank can hold up to 130 litres, depending on the model.

For driving safety and for regulatory reasons, when the vehicle is in motion the fill quantity must be reduced to approximately 20 litres. If the water is drained using the safety drainage handle (see section 10.2.3), a residual quantity of approximately 20 litres will remain in the water tank.”

 

It’s possible that the “regulatory reasons” reference might relate to countries (eg. France) where a motorhome model is ‘homologated’ and the number of passengers it is allowed to carry is based on the difference between its maximum overall weight and its mass in running order, and the passenger-number datum is recorded on the motorhome’s registration document - but that’s just a guess.

 

The less water there is in the fresh-water tank, the ‘safer’ a motorhome will be when it’s being driven. Acceleration will be better, braking and handling should be better, and any reaction from the water sloshing about in the tank will be minimised. The downside, of course, of driving with a near-empty fresh-water tank is that - if you don’t stay in one place long and don’t use campsite facilities - you’ll probably need to keep refilling the tank.

 

This 2017 MHFun ‘hunt-the-drain-valve’ enquiry related to a Knaus Boxstar, but the principles discussed apply generally.

 

https://www.motorhomefun.co.uk/forum/threads/fresh-water-tank-capacity-limited-to-20-ltr.148324/

[monique.hubrechtsgm]

This is most nonsence i ever read. If your Ducato has a 60, 90, 120 ltr tank diesel tank you can drive safely full. They are designed for it to drive full, the same as your garage limit in weight. And your water tanks. Another bottle neck will be if the converters compromise this. Like a bad wall entrance connection to your fuel tank and water. You will have warrantee on water ingress for years if you pass inspection by the books.