Abstract: A method includes operating a water electrolysis device for producing hydrogen and oxygen from water. A PEM electrolyzer (1) is integrated in a water circuit (4) in the electrolysis device. The water circuit (4) feeds reaction water as well as discharges excess water. The water circuit (4) is lead past the PEM electrolyzer (1) via a bypass conduit (14) on starting up the water electrolysis device.

Abstract: A method for operating a water electrolysis device produces hydrogen and oxygen from water. In the electrolysis device, water which comes from a PEM electrolyzer (1) is fed to a first heat exchanger (10) for cooling, subsequently to an ion exchanger (11), then to a second heat exchanger (12) for heating and again to the PEM electrolyzer (1), in a water circuit (4). The heat exchangers (10, 12) form part of a common heat transfer medium circuit (20) at a secondary side. The heat transfer medium circuit includes a cooling device (24), through which the heat transfer medium flow is selectively led in a complete or partial manner or not at all, for the control and/or regulation of the temperature of the water which is fed to the ion exchanger (11) and/or to the PEM electrolyzer (1).

Abstract: A method for operating a water electrolysis device for produces hydrogen and oxygen from water. A throughflow direction is reversed by way of a suitable activation of valves (17, 18) in order to increase a service life of a PEM electrolyzer (1). This is effected periodically such that an equal throughflow in both directions is effected, by which the service life is increased.