to prevent liquid working medium from being sucked in from the feed water tank 14 as a result of the subsequent operation of the feed pump 6 the first valve 15 which is arranged between the feed water tank 14 and feed pump 6 can be closed after the end of circulation of the working medium the first valve 15 being closed the feed pump 6 sucks in only water which is located in the line 29 between the first valve 15 and the feed pump 6 this is only a small quantity of liquid working medium in the line 29 between the first valve 15 and feed pump 6 and is conveyed through the feed pump 6 into the line 24 as a result of the subsequent operation of the feed pump if a second valve 28 is located in the line section 24 this second valve 28 is opened after the end of circulation of the working medium the second valve 28 being opened the liquid working medium from the feed pump 6 and the line 29 between the first valve 15 and the feed pump 6 can be distributed in the entire line section 24 in a further exemplary embodiment of the method according to the invention the condensate pump 13 is subsequently operated after the end of circulation of the working medium in order to convey liquid working medium at least out of the subsequently operated condensate pump.