It's not possible to change on the current generation Balboa, Gecko and other brands of control systems. All hot tub control systems can only heat to maximum of 104F / 40C per the the Consumer Products Safety Commission and Underwriters Laboratory (UL). Any hot tub or spa manufacturer that produces a control system, or modifies a standard control system, to exceed 104 °F is in violation of their UL listing and will have their listing pulled by UL.
Pool and Hot Tub Depot Those are not EU regulations are they? I live in Iceland. I NEED my hot tub HOT not just luke warm :) For me a 40°c tub is pointless 😬
