Aatos Lehtila

In the winter all of the heat lost from the water heater goes to heating the space that it is in.  If that is in some part of your insulated dwelling, then you would have to consider the cost differential between heating with electricity (hot water tank) and your house heating source. No matter what your house heating source, it does cost something.  Summer is a different story, of course.

Just ran across the post now, so I assume you have solved your problem.  My shaft actually threaded into the body of the stove itself and froze there.  I had to drill and pound it out and am now making a new part myself, without the threads on it.  What a stupid design.  I am goiing to be using a 3/4" shaft and a collar to keep it in place.