Help, dog water bowl heater ran by solar thermal energy...

[Sunking]

its not true and I and everyone elso doesnt know it either. Open wire jug elements were made for about 60 years and were made in the millions. The jugs were porcelain and had replaceable elements...FACT believe it or not.
If your statement was true how would cold water get hot using an open wire element in the COLD water? IF there really was a short circuit it would not be heating the water.
And at 12v dc the amount of loss between 2 electrodes(wire) in water would be miniscule compared to the current flowing in the heater(nichrome wire) element.

OK John drop your blow dryer in the bathtub while taking a bath and let us know how it works out for you.

[Sunking]

Pure water is actually a pretty poor conductor - might even call it an insulator.

That is true but there is no such thing as pure water available. It is the minerals and inpurities dissolved in water that make it a conductor.

[inetdog]

OK John drop your blow dryer in the bathtub while taking a bath and let us know how it works out for you.

I sure do not plan to do that experiment!
Also, some vaporizers use bare electrodes with no resistance wire between them to heat the water. But you have to add a measured amount of salt to make it work. It has the advantage of stopping the heat once the water has evaporated. But they are carefully designed so that you can't touch the water!
Do you remember the electric hot dog cookers that just stuck an electrode into each end of the hot dog? That only works because of the salt in the dog.
But as a practical matter, the difference between 120 volts AC and 12 volts DC is pretty substantial. You would still potentially be electrolyzing the water, but not as fast.
And the dog might feel a tingle in his tongue, but would not be harmed. (How many of you have "tasted" a 9 volt battery on your tongue?)

I think that the major objection would be that the resistance would not be controlled and so the heating rate would be unpredictable.

[Sunking]

I sure do not plan to do that experiment!

Well folks who think water is not conductive might. They will change their mind real quick if they survive.

Also, some vaporizers use bare electrodes with no resistance wire between them to heat the water. But you have to add a measured amount of salt to make it work. It has the advantage of stopping the heat once the water has evaporated. But they are carefully designed so that you can't touch the water!

Or baking soda to lower the resistance enough for the voltage it operates at.

Do you remember the electric hot dog cookers that just stuck an electrode into each end of the hot dog? That only works because of the salt in the dog.

Did it many times when I worked for a utility during demostations at public elementary schools. We did not use the manufactured cookers, we used very high voltage to demonstrate what would happen to fingers if they touched a high voltage line. The hot dogs explode. It is not nessecarly from the salt content but the water content with all the impurities and dissolved metals like magnesium, zinc, iron and copper found in all meat and most water.

In the field during the winter working outside we used 2 nails connecters to a pigtail plug into 120 VAC. Submerged the nails into a pot of water and bring it to a boil in just a minute or two so we could make coffee and hot chocolate.

You are correct you can submerge nichrome wire in water and pass current through the wire. At the same time the water will form a parallel path and also conduct more current. Current through a resistance develops heat aka power in watts However even at 12 vdc the dog would jump back when he feels the current flowing in his tongue just like you do tasting a 9 volt transistor battery. Farmers are very much aware of the problem with stray voltages at cattle water tanks induced by currents flowing through a MGM utility line. The potential difference between the cows feet and water tank is very small measured in the milli-volts, but is enough to cause the cattle not to drink from the tank.

[rick1]

run parallel water lines from your engine cooling system to an old vehicle water heater and place under water pans. You will have plenty of heat.

[john p]

Just about all the heating of the water was done by the element NOT BY CONDUCTION OF ELECTRICITY BETWEEN THE 2 BRASS RODS.

[Mike90250]

unless you actually buy bare nichrome wire, you are usually "getting" a composite element, often called CALROD.

http://en.wikipedia.org/wiki/Heating_element

Tubular (sealed element, often known by the trademark "Calrod"): a fine coil of Nickel chrome wire in a ceramic insulating binder (MgO, alumina powder), sealed inside a tube made of stainless steel or brass. These can be a straight rod (as in toaster ovens) or curved to span an area to be heated (such as in electric stoves, ovens, and coffee makers).

Any heater "wire", uninsulated, in water, is a hazard.

[Sunking]

unless you actually buy bare nichrome wire, you are usually "getting" a composite element, often called CALROD.

http://en.wikipedia.org/wiki/Heating_element

Tubular (sealed element, often known by the trademark "Calrod"): a fine coil of Nickel chrome wire in a ceramic insulating binder (MgO, alumina powder), sealed inside a tube made of stainless steel or brass. These can be a straight rod (as in toaster ovens) or curved to span an area to be heated (such as in electric stoves, ovens, and coffee makers).

Any heater "wire", uninsulated, in water, is a hazard.

+1 Warm Fuzzy Mike. That is the point I have been trying to make.