Good advise. Thank you.
I reason for the upsize in water heaters is because I just remodeled my masterbath and installed a large jacuzzi type tub (65 gal). I had a spa-tub before but it was smaller. Honestly, we don't/didn't use the tub much, but I still want to be able to completely fill it with hot water when we do use it. I think that is why the "product calculator" recommended the 65 gallon unit.
I also want to make sure I don't have to upsize any of the wiring to the heater so staying with the two 4500W elements (which is what I have now) should mean I can do a direct replacement. Maybe the 4500 and 5500W units will not require a wiring upgrade but I don't have any knowledge of this - so I thought I'd play it safe. (I have two 30A breakers (240V) for the service to heater).
It is odd that the 80 gallon tank is a few dollars cheaper than the 65 gallon unit. Should I go with the bigger unit, or will I just be wasting money heating water above the capacity I need?
Thanks again. Great forum.