3 Phase is cheaper to operate than single phase. 1/3 the power just bounces around the windings and is therefore 150% cheaper to run a 3 phase motor than a single phase motor at the same power range.
You can google it if you want or you can read this article to see that the guys here that believe 3 phase is cheaper to operate are correct!
A 3 phase motor may be cheaper to run than a single phase, but a 13 SEER air conditioner costs exactly the same to run no matter how many phases it has.
Its like saying that two different cars get 13 MPG, but one uses half the gas of the other. Not possible. If it used half the gas it would get 26 MPG.
also, single phase motors used in the HVAC world have nifty little efficiency boosting devices called run capacitors, which brings the efficiency much closer to that of a 3 phase motor.
I need some more information about this magical A/C thats 150% cheaper to run. Seems like that means the utility would be PAYING ME to run it. Im gonna pack as many as possible into my garage, airflow clearances be damned. Then I'll just turn em on, sit back, and watch the money roll in
If you run a single phase unit an a 3 phase service and dont balance the 3rd phase with some other load , it will cost more to run due to your meter using your highest amp leg to spin the meter. Other wise it is the same.