Why choose a 230 v air conditioner over a 115 v

Question

Is it cheaper to operate?

Answer 1

It's not an option. You have to use 230V if you are in Europe(and Asia except Japan). If you are in North Am, use 115V.

It's the power rating that determine the cost of operation and the size of the room.

Answer 2

In the US, the size of the air conditioner will determine the voltage.  An air conditioner rated at about 7,500 BTU's or less can run on 110 volts but you can get them for 220 volts also.  Over this rating, the A/C will need 220 volts.  The current draw is what determines which voltage you use.  7,500 BTU's will need about 20 amps from a 110 volt circuit.  That's pretty much the limit for a 110 volt circuit.  A 10,000 BTU A/C would need about 14 amps from a 220 volt circuit and about 28 amps from a 110 volt circuit.  This is why an electric water heater, clothes dryer, and stove use 220 volts.  The current draw would be too large for 110 volts.