Most 240v heaters have two wires attached at seperate locations, and I believe they are both 120v? if this is the case are there two elements within the heater?
I assume the heater operates with 120v input and then grounded at the other end, similar to something like a hair drier or toaster oven.
I did see in another posting there should be approx. 10-15 ohms of resistance between the two connectors/posts. I am a little confused on the operation of the heater, any help would be appreciated.

Below is a link that will show you what a basic 220V heater looks like, each lead to it is 110V (positive and negative) in order for a heater to function it has to have resistance to it, while grounding it would work it would destroy any function your GFCI serves and would not protect you if the heater were to burst open and allow electricity into the water (we're cooking now) there are almost never two elements and if there were then it would have 4 leads going to it and not just two. In order for ANY circuit to function it has to loop through and have some sort of resistance between the two sides.
http://spapartsnet.com/p_Heater-Element ... 6_0_1.html