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Water flowing from pipe under the van


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Might be just a newbies misunderstanding but I am confused. Just about to go away for the night and are filling the fresh water tank when we noticed that the water is coming out of a black pipe at the bottom of the tank (see picture). Pretty sure we did not turn anything that we were not supposed to turn! Manual says something about frost control but then offers no more help. Any ideas welcome.
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On your Water boiler you will find this valve, it is a pop up valve that opens at low temperature to prevent your boiler freezing, just push the valve top down to close it, if too cold in your wardrobe where often the boiler is situated it may pop up again so just get a bit of heat in there and it should stay closed, some folks place a clothes peg around the valve to prevent it opening and dumping all your water, this is OK but if you do it you MUST remember you have done it and make sure it DOES NOT FREEZE by default.
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Dacswells - 2020-12-14 11:36 AM


It started when we turned on the pump. Just realised photo had not gone up.

So yes, frost valve. Locate the valve and push, pull, press to find the way to close it.


There is a slim possibility it is 12 volt powered and requires the control panel to be turned on before it will close. This will be obvious if it has wires going to it.



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Just for the record...


Damian’s forum Profile states that his motorhome is a 2020 Knaus Boxstar.


The chances are near-nil that this vehicle will have the old-style Truma electrically-operated safety/drain valve mentioned by vindiboy above (upper attached image below). This valve was superseded around 2007 by a manually-operated valve called ”FrostControl” (lower attached image below).


The Truma electrically-operated safety/drain valve can easily be jammed in its closed position to prevent it opening spontaneously in frosty weather conditions. (Lift red knob UP to close valve. Push red knob DOWN to open valve.)


However, closing the FrostControl valve (lower image attached below) is a 2-stage procedure comprising turning Knob A to its crosswise position and then firmly pressing in Button B. This procedure was described here in 2015




and there’s a YouTube video about FrostControl here



The 2-stage closure method makes it much more difficult to ‘jam’ closed a FrostControl valve (useful if the motorhome’s fresh-water system is to be filled in cold weather). Truma offers an an electric ‘add-on’ heater for the valve, but that tends to conflict with the valve’s basic manual-operation premise.




(I DIYed a gizmo to ‘jam' my Rapido’s FrostControl valve closed. In theory it should work, but I’ve never needed to use it so I can’t be sure.)



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