Abstract: A motor vehicle heating system which is provided in a motor vehicle coolant circuit containing a motor vehicle engine, a motor vehicle heater with a heat exchanger and an associated blower, and a fuel operated heating device that is independent of the motor vehicle engine and is connected upstream from the motor vehicle heater, and a process for operating such a motor vehicle heating system, by which the motor vehicle engine in the motor vehicle coolant circuit is heated first to a temperature which is low yet facilitates its starting, and then the coolant is heated so that the motor vehicle heater can provide heat quickly. Until a first predetermined temperature of the coolant is reached, the coolant, is circulated in the complete motor vehicle coolant circuit.

Abstract: A heating apparatus, which is intended, particularly, for incorporation into a vehicle liquid heat exchange circuit has a control device, to which a liquid flow measuring device is connected. If the liquid flow measuring device detects that a predetermined liquid flow has been reached or exceeded, the control device of the heating apparatus can be put into operation as a function of other control variables. If, on the other hand, this predetermined liquid flow is not reached or exceeded, the control device, by its connection to the liquid flow measuring device, prevents turning on of the heating apparatus. As a result, the heating apparatus is turned on and delivers heat only if a heating requirement exists.

Abstract: A piston pump, in accordance with several embodiments, comprises a suction chamber into which fluid medium enters from an inlet line via a suction valve, beginning at the outset of a delivery stroke of the piston pump, without a build-up of intake negative pressure during the delivery stroke of the piston, and is particularly adapted to prevent vapor bubble formation. A reliable pump closure is ensured in the vicinity of the pump outlet, independent of the spring action of a return spring, which bears against the piston, in that any fluid medium entering the suction chamber of the pump contacts the piston in a direction producing reinforcement of the outlet closure pressure. In accordance with preferred embodiments, the piston may be a partially hollow or entirely hollow piston instead of a solid one.