How "hot" your motor runs is determined by the amount of current (amperage) it is drawing. If you size the motor appropriately (based upon the size of your pool and your usage) then it will run as "hot" as is "normal" for its usage and environment. A 1 HP motor set up for 230V will use or draw less current than a similar 1 HP motor set up for 115V. In the world of electricity and motors 1 HP = 746 watts of "power". Power (P) = Amperage (I) X Voltage (E). So using my example of a 1 HP motor, at 115V it would be drawing 6.5 amps (746/115 = I) vs. at 230V it would be drawing 3.25 amps. More current (amps) = more heat generated (all else being equal). Heat is the enemy of motors. My calcs are rounded and approximate. Utilities bill for the watts used, so you would pay the same for usage of each motor, but the higher voltage rated motor would generate less heat. I would suggest you run your motor at 230V if you are setup to supply it with that. Sorry if the answer got sort of technical, but that's electricity for you........