A larger tank with proper air pre-charge will mean fewer start-stop cycles for the pump. That will increase pump life and lower the power bill. Starting requires a big power input surge. Some online charts show how to size a tank. But larger is better- period. Mine is 80 gallons and that is all that I could personally handle-- almost too big to hug! Also additional tanks can be placed anywhere on the cold water piping system if space is a limitation for the size you prefer.

thanks! that is sort of what we thought. I asked them to install a 64gal. I have a 32 now, 44 was next size up. I have the room for the 64---at 22" diameter. as they get bigger the diameter stays the same at 22, and the height increases. I am hoping doubling in size will result in a longer life for the pump. The power surge at start should be the same either with the 32gal or the larger 64gal, right??