Aqua Hot 200 no hot water with the electric element?

I have found the high temp limit switch to be the typical cause of failure but my unit is a 100 so it's a bit older. I now carry a spare for both the diesel and hot water side. In a pinch I jumped the limit switch until a replacement arrived.

Note: the high temp limit switches on mine are not resetable...they are more like a fuse and once activated they're toast.