The invention relates to an automatic cylinder changeover device (1), comprising two gas inlets for mounting gas cylinder banks, namely the left gas inlet and the right gas inlet, a gas outlet through which gas may be discharged and a valve suitable for connecting said left gas inlet or said right gas inlet with the gas outlet and configured for automatically reversible switching between these two connections, characterized in that the device (1) comprises an indicator, suitable for being manually set in one of two distinct positions, one of said positions indicating the left gas inlet and the other of said positions indicating the right gas inlet and comprises means for detecting the position of the indicator, including at least one sensor (5), preferably a pair of sensors (5).The invention also covers a method for monitoring a gas installation equipped with such automatic cylinder changeover device.