A new design of a wind water heater (WWH) is presented. In this new system, the wind energy is directly converted to thermal energy used to heat the water. The wind energy is converted to frictional thermal energy by dissipation within a thin layer of oil. The oil is filled in an annular gap confined between two horizontal concentric cylinders with different diameters; the outer insulating cylinder is rotating while the inner cylinder is fixed. The heat generated is transferred into the inner cylinder then to the heat exchanger. The heat transfer fluid is carrying the heat from the heat exchanger to the water storage tank by mechanical pump. A mathematical model is proposed to model the system mechanical and thermal behavior. The theoretical model has been solved analytically to estimate the amount of thermal energy generated by the system based on a given wind design speed at the site. The theoretical performance of the proposed heater is analyzed and the effects of different design parameters on the heater performance are investigated. The theoretical predictions of the system performance show that the efficiency of proposed wind water heater at design wind speed is equal to 34.8%. The relatively low conversion efficiency of kinetic wind energy to sensible thermal one is due to the limitation imposed by the windmill performance.