Overall the 11kW uses the same amount of electrical energy. It just has a heating rate that is twice as fast, therefore it will run half as long and in the end use the same amount of electricity as the 5.5kW heater would have. It is common for our customers who use their hot tubs relatively frequently to keep their water temperature setting pretty warm. And in such cases, the speed at which the system will heat up the tub is not all that important. Also, with the addition of the optional WiFi remote module, you can turn up your hot tub from anywhere in the world if you have a smartphone or tablet and a data connection! This makes it less imperative to have a fast heat-up rate as well. However, the larger the heater you have, the more flexibility you have. You can still set it however you want and if you find yourself in a situation requiring a faster heat-up time, you’ll have the heater to do it. Keep in mind, gas heaters far outperform electrical in both efficiency and heat-up rate capabilities.