Anyone have any comments on a totally electric house and running one of these electric tankless water heaters. I am looking at a 200 amp service pannel. But the water heater requires 3 40amp double pole breakers. For the load calc the manual says you can use 47 amps because it is not on all the time. Sure seems like in the summer with the ac going the wife cooking and I go take a shower there goes the lights. Anyone have this setup or installed in a new house. Not completely sold on the water heater yet.