Most larger spas require 220v. However, Creative Energy’s mid size and smaller spas can be either 110v or 220v. The efficiency is exactly the same. When a spa is wired 220v, both the jet pump and heater can be active at the same time. In the 110v, the heater is deactivated when the jet pumps are turned on. When the jets are turned back off, it automatically resumes heating. 220v spas heat the spa after the initial fill up 3 times faster than 110v spas. Again, same amount of kilowatts used.