I live in Ohio, about 40 miles north of Cincinnati. I do not have a demand meter. The 2, 5500 watt elements were probably both working at the same time. Maybe I could have used a smaller than 40 gallon heater?
I’ve also thought of just heating the room with the pex in the slab. I think I should wait for improvements in technology.
I cool with an 8,500 and a 6000 btu window A/C, I’m also thinking the heat pump water heater in the cellar to hide it from the tax appraiser. I would entertain a window unit with a heat pump.
I appreciate the input and interesting links everyone is supplying. Eric