Tank heaters.

[Guest Michael Shaw]

I keep hearing that 12 volt tank heaters are available, suitable for use against the freezing of fresh & grey water tanks. However,I have totally failed in my own efforts to trace makers or suppliers. Can anyone help please ?. Perceptive Forum readers may by now have guessed that we are designing our own 'van. Thank you.

[Guest richard]

HI Try CAKtank they do a couple richard

[Guest Derek Uzzell]

You might want to consider incorporating in your design the PC-100 or PC-200 control-system kits also marketed by CAK. These are produced by the Italian company CBE and are currently used as original equipment by many motorhome converters as installation is much simplified. My Hobby uses a PC-100HB-T system that carries a Hobby logo on the control-panel (hence the "HB") and has a switch for a waste-water tank heater (hence the "T") replacing the normal awning-light switch. (This may just be a 'badging' thing, as the CBE documentation indicates the same 10A fusing for awning-light or tank heater.) To enable the tank heater one needs to switch on the control-panel's main switch first, but (to avoid the leisure battery being flattened inadvertently) the tank heater will only operate when the engine is running or the vehicle is connected to a live 230V mains supply. It needs saying perhaps that there is little genuine benefit in heating the water in a tank if the pipework to/from it, and the drain tap, remain vulnerable to frost. Encapsulating tank, pipework and tap in an insulated box would help enormously, otherwise you could wrap everything in insulating material (also sold by CAK) before installing it on your vehicle. Phone 0870 757 2324 for a CAK catalogue.

[Guest Brian Kirby]

1 I don't like the sound of a heated (albeit nominally) fresh water tank. The stored water should be kept as cold as possible to avoid organic growths. I know the water won't actually be made warm by the heater, but any heater element would have to cause quite a temperature rise in the immediately surrounding water, for that heat to be conveyed to the rest of the tank and prevent freezing. That localised warmth seems likely to be sufficient to promote, and circulate, organic growth. 2 I think you should, unless really impossible, mount the fresh water tank inboard, in the usual place (low down, under seating etc) so that it is away from daytime heat, kept dark and protected from freezing in winter by the on board space heating. 3 If you go to places in winter where the temperatires are really low, (sking etc) then no amount of insulation will prevent eventual freezing of an external tank. Remember, all insulation does is slow down the rate of heat transmission. If external temperatures are below zero on a 24 hour (or nearly so) basis, the temperature of your stored water will inexorably fall towards the external ambient temperature. 4 Also, as you consume water the stored mass diminishes and with it, the number of calories required to convert the remianing water to ice. In short, a partially empty tank will freeze up more rapidly than a full one and maintaining a full tank when all around is frozen (including possibly the supply point!) is not so easy. 5 Concerning heating to the waste tank, I think the best (and simplest) approach was recommended in an article I saw some tame back. I believe this is the commonly adopted method in Alpine winter sports campsites where -15C is not uncommon. Leave the drain cock on the waste tank open, so any waste water runs straight out. Assuming the waste water is warm, the cock itself, and the waste outlet, shouldn't freeze. Then, put a bucket under the drain pipe and regularly dispose of its contents, if necessary down a toilet. It's a bit of a fag, but it is virtually foolproof and it will work even if the power goes off (and also if the dump station has frozen up or otherwise been taken out of use: not all service areas maintain full functionality during winter). It also avoids the need to move the 'van for anything other than topping up fresh water. 6 Most winter camping sites with electrical supply points will also have heated amenity blocks, so the amount of water you use shouldn't be that great anyhow. 7 Final thought, if you do fit a waste tank heater (assuming your waste tank is externally mounted) it must work while you drive as well as when parked. You may not be able to empty (for reasons as above) exactly when you want, and you therefore can't eliminate the possibility that you may need to drive around with some waste still in the tank. A few miles of -15C will soon freeze even an insulated tank. With inoperative heater elements extending into the waste water they'll get embedded into your nich big block of ice. When the ice begins to thaw it'll do so around the edges first, because thats where the heat will come from, so wou'll next have the ice block floating in water. As you travel the block will try to surge around inside the tank, but will be restrained by your embedded heater elements. Not good! 8 Final, final thought! When you get it all done, if you are in a winter sports area and camped on/surrounded by snow/ice, do move your hook up cable every day. Slowly and imperceptably, because the cables are slightly warmed by the flowing current, they sink down through the snow/ice and become trapped in. After aweek or so they're so frozen in they become irrecoverable and many have to be abandoned. So, you move your cable every time you empty your bucket, see! Hope this helps Brian

[Guest Michael Shaw]

Thank you All, My computy box thing must be playing up - I've only just seen your replies so apologies for my delayed thanks.