Dryer with improved process air circuit airtightness and corresponding method of operation

The present invention relates to a dryer comprising a drum and a process air circuit, the process air circuit comprising: a blower driving process air; a condensing device that condenses moisture in the treated air from the drum; a condensate tank in which the condensate collecting container receives water transferred from the condensate collecting container; the overflow container is used for placing the condensate water tank; the electric pump unit is used for pumping water in the condensate water collecting container to the condensate water tank; a pump conduit connecting the pump outlet with the inlet of the condensate water tank; the overflow guide pipe is used for connecting the overflow container with the condensate water collecting container; and a siphon located in the pump conduit and/or the overflow conduit to restrict air transmission through the conduit. The dryer includes a bypass conduit directly connecting a pump conduit and an overflow conduit, the pump conduit including a flap system adapted