Abstract: A heating oil pump which is intended for selective single or double line operation. Between the suction side and return side there is a connecting passage which, for double line operation, is closable by a closure member. The latter is displaceable upon insertion of a plug from a closed to an open position by an actuating element which projects into the inserting path of the plug and, upon removal of the plug, back to the closed position by a return spring. This results in automatic change-over without the need for the return pressure to be higher than the suction pressure.

Abstract: The invention relates to a fuel burner pump assembly of the type having a main regulating valve for controlling a supply of fuel to a burner nozzle and a flow responsive bypass valve for bypassing fluid from the main valve until a predetermined flow rate is achieved. A check valve downstream from the bypass valve and in series therewith has a small predetermined opening pressure which facilitates the operation of the bypass valve. The check valve utilizes a rubber sleeve as the closure member thereof which enhances the operation of the bypass valve by operating to close tightly despite the presence of small dirt particles in the fluid flow.