Agree on the cost. I looked into doing this instead of putting in a new tank. I have an all electric house with a 400A entrance (actually, two 200 A boxes). I have plenty of capacity. But, the cost of the installation was prohibitive since the wire would have to run 75 ft. from the box to the unit.What Marty said. I suspect once you find out what it would cost you, you'd change your mind about a tankless heater.