# Water loss.



## bc109 (Sep 17, 2016)

Arrived home. Time to remove water. Slowly, slowly !
A question about water drainage. I switched off 12V at the main controller to allow the boiler
release valve to drain the water out of the Truma ( C 3400 ? ) boiler.
To my surprise, the water from the main tank also drained away.
Question: Is this normal, or do I have something else to learn about the plumbing, or do I 
have a fault somewhere ?
All donations........!
Bill


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## TeamRienza (Sep 21, 2010)

I have only ever drained the heater after emptying the main tank on my previous van (Autosleeper), and current van (Hymer B598). It sounds like the system is working backwards on yours, in other words due to draining the heater, the flow out is trying to fill by taking the water 'out' through the 'in' pipe. I assume there is no nonreturn valve in the line and the outlet of the drain pipe being lowest, is creating a syphon.

Just an innocent musing which could be entirely wrong, but is this not a problem for people with the frost dump valve to protect the heater. I think I have read that people's main tanks are unwittingly drained.

I dare say others will agree or disagree and provide an answer.

Davy


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## Spacerunner (Mar 18, 2006)

in my case the pump fills the boiler, so if the boiler drain valve is opened and the water pump is left on then as soon as the water level , and pressure, drops the pump will attempt to maintain the water system pressure. If left the pump would empty the main fresh water tank through the boiler drain valve.


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## nicholsong (May 26, 2009)

Spacerunner said:


> in my case the pump fills the boiler, so if the boiler drain valve is opened and* the water pump is left on* then as soon as the water level , and pressure, drops the pump will attempt to maintain the water system pressure. If left the pump would empty the main fresh water tank through the boiler drain valve.


Bill(OP) said 12v was OFF


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## Pudsey_Bear (Sep 25, 2008)

Gravity springs to mind on this one.

I normally use the pump to empty the fresh tank and water heater, turning off the pump once the tank is as empty as my drive will allow, the heater is usually drained by then.


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## bc109 (Sep 17, 2016)

There is certainly a frost dump valve on the Truma, and this is the one I activated by turning off the 12V at source. Sounds like others
have experienced the same effect, but there is nothing in the Hymer instruction manual to suggest that this should happen.
I'm looking for a fault. Perhaps there isn't one. 
Bill


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## Glandwr (Jun 12, 2006)

The dump valve on our water truma (I simply press it down rather than switch off 12v feed) will also empty the whole of the fresh water tank. It is a syphon effect, not the pump. Our pump is activated by a micro switch. I take it as a conscious design feature. Wouldn't want a block of ice. 

Dick


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## Pudsey_Bear (Sep 25, 2008)

We've never had anything but the Truma manual flip up type of drain valves.


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## KeithChesterfield (Mar 12, 2010)

Not sure what you're valve looks like but my Truma frost control is as the picture below.

'A' should be in line with the flow of the pipes and 'B' pressed in.

If either are in different positions the water will flow from the tank.

Hope this helps.


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## BillCreer (Jan 23, 2010)

Because I always activate the frost dump valve and the main tank drain valve at the same time I have assumed that you have to do both. Filling the boiler is not an automatic pump thing as it only transfers water from the main tank when you turn on a hot tap. Next time I'll just hit the dump valve like you and see if it siphons because I can see the logic in that. If it was warmer I might have gone out and tried it now.


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## Pudsey_Bear (Sep 25, 2008)

BillCreer said:


> Because I always activate the frost dump valve and the main tank drain valve at the same time I have assumed that you have to do both. Filling the boiler is not an automatic pump thing as it only transfers water from the main tank when you turn on a hot tap. Next time I'll just hit the dump valve like you and see if it siphons because I can see the logic in that. If it was warmer I might have gone out and tried it now.


If it's as cold there as it was here last night, I hope your pipes are okay Bill.


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## bc109 (Sep 17, 2016)

Thanks for all your replies, folks. We have had hail once in the fifteen years we have lived here, and I recall frost on the windscreen once when going to the airport at sparrowfart. We drain everything simply to have fresh water when we set out.
We have some of this magic water purifying stuff ( very expensive ) but belt and braces approach wins every time. 
It looks like this draining of the main water tank is a "natural Hymer phenomena" and nothing to worry about. It also answers a query about why we ran out of water unexpectedly after getting the control unit repaired at Schaudt.
More questions coming up thread by thread !
Cheers
Bill and Dorli


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## BillCreer (Jan 23, 2010)

I drained mine weeks ago so to test the siphoning theory I would have to refill it and no hose in the garden because of the frost.


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## peejay (May 10, 2005)

I've drained my boiler and pipes before (opening truma dump valve, all taps and both pipe drain taps in the garage) but left the bung in the water tank and it hasn't syphoned off the tank water contents.


I've done this in the past if the van is temporarily laid up between trips when there might be a slight frost but not bad enough to warrant emptying and wasting a full tank of water.


I also take out the water pump fuse just in case the Reich control panel is switched on to operate other stuff in the van as the micro switched taps are left open.


Pete


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## Glandwr (Jun 12, 2006)

Funny I'm just about to take my pump out. I had changed it a couple of weeks ago, the old one having worn out. Since then I lose the head of water over night, air must be entering one of the joints inside the tank. I will tighten the joint. But as a consequence I bet the syphon effect wouldnt work, in the mornings anyway.

Dick


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## bc109 (Sep 17, 2016)

Maybe it's only the oldies that have this "facility". Sennen523 in an earlier thread wanted to know how to drain his main tank. But
he/she? has a much later Hymer.


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## BillCreer (Jan 23, 2010)

On mine I can only see the siphon working if the taps are left closed as air could enter the system from three positions. You would need, apart from the inlet (fresh water tank) and outlet(boiler drain), a sealed system for a siphon to work.


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## bc109 (Sep 17, 2016)

*The plot thickens.*



BillCreer said:


> On mine I can only see the siphon working if the taps are left closed as air could enter the system from three positions. You would need, apart from the inlet (fresh water tank) and outlet(boiler drain), a sealed system for a siphon to work.


Now that is worth experimenting with the next time I fill up and then drain boiler. Actually, it wouldn't need much 
water in both tank and boiler to try that theory out.
So thanks for that suggestion.
Bill


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## HermanHymer (Dec 5, 2008)

In my Hymer apprenticeship days I had a situation where the leisure battery failed while at a rally. Next thing - "water all gone". There's a tap (like an extending stopper) on top of the heater which needs to remain in the "UP" position to keep the water in. Push it down manually, or switch off the power (to it), and the water drains out of the heater AND the water tank. Trick is to put a peg on the tap to keep it UP if it needs intervention. But it is an override with the attendant risks if you should do that. (Thanks again to Clive1921 who sorted it out for me at the time).


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## kenny (Jun 4, 2005)

if you look at the pipe work ,you will see it comes from the main tank to the pump,most newis vans have a bloke of connectors ,which is feed from the pump, so that where you want water from it comes direct,on its own pipe, so if you open the frost valve it will drain off all the water ,then drain the rest off by gravity


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## bc109 (Sep 17, 2016)

Last week we had snow. Two days before the weather turned nasty, I drained the boiler, leaving the taps closed. The main water tank was about one third full, thanks to work on improving shower pressure, which was resolved; electrical feed to pump was reversed, now it's correct and shower works for the first time.
Strange to say, after all the arguments, siphoning, gravity, you name it, did not apply this time and in the morning, I had to go to drain the main water tank which was still one third full.
The jury is still out.
Bill


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