摘要 |
A wind operated heating device is operated by a rotor. The heater (2) has a liquid reservoir and a rotary element (6) which is immersed in the liquid in the reservoir. The rotary element (6) is driven by the rotor so as to heat the liquid. The rotor is connected to the rotary element (6) by a shaft. A shield (30) is arranged to rotate with the rotary element (6) and is movable relative thereto such that the position of the shield member (30) relative to the rotary element (6) varies in dependence on the rotation speed of the rotary element (6) so that the shield member (30) provides a greater resistance to rotation at higher speeds than at lower speeds of rotation. <IMAGE> |