An installation for feeding a gas-consuming member with combustible gas and for liquefying said combustible gas, the installation including: - a leaktight heat-insulating tank including an inner space intended to be filled with combustible gas in a liquid-vapor two-phase state of equilibrium; - a heat exchanger (10, 110) placed in a higher position than the leaktight heat-insulating tank, the heat exchanger comprising a first path (15, 115) and a condensation path (12, 112) separated from each other in a leaktight manner by heat-exchange walls allowing heat to be transferred between a fluid contained in the condensation path and a fluid contained in the first path, the first path and the condensation path each including an inlet and an outlet, - the inlet of the condensation path being connected to the leaktight and heat-insulating tank by a vapor-collecting circuit (13, 113, 213) including an admission emerging in an upper portion of the inner space of the tank to withdraw a first stream of vapor-phase combustible gas in the inner space of the tank; the inlet of the condensation path is placed higher than the outlet of the condensation path, - the outlet of the condensation path (14, 114) being connected to the inner space of the tank to transfer by gravity a liquid fraction of the first stream of combustible gas in the inner space of the tank, the liquid fraction of the first stream of combustible gas being obtained by condensation in the condensation path, - the inlet of the first path (15, 115) being connected to the leaktight heat-insulating tank by a liquid inlet circuit (17, 117), the liquid inlet circuit including an admission emerging in a lower portion of the inner space of the tank to withdraw a second stream of liquid-phase combustible gas in the inner space of the tank and a circulation pump to transfer the second stream of liquid-phase combustible gas into the first path, characterized in that the first path is a vaporization path, the installation further comprising a vacuum pump connected to the vaporization path (15, 115) to place the vaporization path of the heat exchanger at a pressure below the pressure prevailing in the vapor phase of the leaktight heat-insulating tank, and in that the outlet of the vaporization path (3, 103) is connected to a gas-consuming member to transfer a vapor fraction of the second stream of combustible gas to the gas-consuming member, the vapor fraction of the second stream of combustible gas being obtained during functioning, by vaporization of the combustible gas in the vaporization path placed at a pressure below the pressure prevailing in the vapor phase of the leaktight heat-insulating tank. - a leaktight heat-insulating tank including an inner space intended to be filled with combustible gas in a liquid-vapor two-phase state of equilibrium; - a heat exchanger (10, 110) placed in a higher position than the leaktight heat-insulating tank, the heat exchanger comprising a first path (15, 115) and a condensation path (12, 112) separated from each other in a leaktight manner by heat-exchange walls allowing heat to be transferred between a fluid contained in the condensation path and a fluid contained in the first path, the first path and the condensation path each including an inlet and an outlet, - the inlet of the condensation path being connected to the leaktight and heat-insulating tank by a vapor-collecting circuit (13, 113, 213) including an admission emerging in an upper portion of the inner space of the tank to withdraw a first stream of vapor-phase combustible gas in the inner space of the tank; the inlet of the condensation path is placed higher than the outlet of the condensation path, - the outlet of the condensation path (14, 114) being connected to the inner space of the tank to transfer by gravity a liquid fraction of the first stream of combustible gas in the inner space of the tank, the liquid fraction of the first stream of combustible gas being obtained by condensation in the condensation path, - the inlet of the first path (15, 115) being connected to the leaktight heat-insulating tank by a liquid inlet circuit (17, 117), the liquid inlet circuit including an admission emerging in a lower portion of the inner space of the tank to withdraw a second stream of liquid-phase combustible gas in the inner space of the tank and a circulation pump to transfer the second stream of liquid-phase combustible gas into the first path,