When a plug and play spa operates at 120v, the heater (if the spa has one) is mostly a 1kw heater. By converting one of the convertible plug and play spas to 220-240v operation, you make the heater a 4kw heater without needing to actually replace the heater.
Will the spa use more power at 240v? No, because the recovery time and initial heat up time is 1/2 the time. The only thing you are converting is the heater. The pump still operates at 120v even when the spa operates at 240v.
So the benefit of operating the spa at 220-240v is that the heater works better.
On a plug and play spa, the heater is convertible to 240v by removing a white wire and switching a dipswitch on the circuit board.
Your electrician can do this conversion in a few minutes. The steps are to power down the spa, unplug the spa. Remove the power cord by unscrewing the connections on the terminal block on the circuit board. Then remove the jumper wire from the “Red AC” section. Move the number 10 dipswitch down and that converts it to 240v.
Your electrician will then bring in the neutral, 2 hot wires and a ground wire and you are good to go.
See the diagram in the video for how to wire up a GFCI at 240v.
When inside the power control box, do not move the red, factory preset dipswitches. The only dipswitch that needs to be adjusted when converting from 120v to 240v is the last one in the row (dipswitch #10). Do not move any of the other dipswitches at any time without calling for assistance.
Not all 120 volt spas are convertible, so be sure you have a QCA Spas convertible 120 volt plug and play model before attempting to hook it up to 220-240 volts. As of the time this article was written, the only types of spas that accommodate this upgrade are the Mystic, Riviera and StarGazer type spas.