Abstract: A liquid heating system includes a high-pressure hydraulic pump for suctioning the liquid from the liquid reservoir and delivering it thereto through a liquid conduit into which the pump is coupled. A drive is provided for the pump, and a pressure-reducing element is coupled into the conduit downstream of the pump for reducing the pressure and elevating the temperature of the liquid. The element has a fixed flow passage, and a heat exchanger is coupled into the conduit downstream thereof. An arrangement for controlling the discharge rate of flow produced by the pump is provided as a function of the calorific heat required to be generated by the system and/or of the temperature of the liquid.

Abstract: A heating system for the service cabin of a machine operated by an internal combustion engine includes a high-pressure supply pump for feeding oil from the engine oil sump through an oil conduit and returning it thereto, a pressure-reducing element in the conduit for elevating the temperature of the oil, a line by-passing the element and having a flow control valve therein, a heat exchanger connected into the conduit downstream of the element, the pump being located within the internal combustion engine together with its high pressure line to thereby confine any high pressure leaks from such line to the interior of the engine and its oil sump.