A hot tub manifold that has been engineered with a plurality of “teeth-like” raised sections inside the inner diameter of the manifold. As the water travels through the manifold while the hot tub pumps are operating, it travels across the surface of the “raised” sections creating friction. That friction energy created is thus transferred to the water in the form of heat—which in turn raises the temperature of the water to the desired set level on the thermostat on the hot tub. Passing the water (generally at high speed) over the raised teeth creates “free” heat and lowers the amount of time and energy required by the hot tubs element heater to elevate the water to the given temperature.
