JaxDad wrote:
When there’s no liquid in the heater the element quickly overheats and burns out. I’d be surprised if anything else would happen, the element overheats VERY quickly.
SoundGuy wrote:
The OP said he has an SW6D, in which case it has no electric heating element, otherwise it would be an SW6DE. If it is in fact the latter then yes, he's destroyed the electric heating element which would therefore need to be replaced.
And if, indeed, the propane burner came on, it could very easily melt the bottom out of the aluminum tank.
It is indeed imperative that the water heater be full of water when you turn it on. This is not an "oh, gee, sorry about that" kind of error to make.