A heat engine comprising: an expander ; a recuperator ; a heater ; a fluid pump ; a working-fluid path including a high-pressure path for communicating pumped working fluid from the fluid pump toward the expander on a high-pressure side, and a low-pressure path for communicating the expanded working fluid away from the expander on a low-pressure side, the heat engine using a condensable working fluid, which, at least in part of the high-pressure path , is in the liquid phase, the high-pressure path at least extending between the recuperator and the expander via the heater , and the low-pressure path at least extending between expander and the recuperator ; characterised in that it further comprises a fluid-drainage path extending between a first connection point on the high-pressure path and a second connection point on the low-pressure path, the fluid drainage path being selectably open or closed for selectively draining working fluid from the high-pressure side toward the low-pressure side, a first portion of the fluid drainage path being connected to a portion of the high-pressure path , in which during normal operation the working fluid is mainly in the liquid phase, at the first connection point , the first connection point being located on the high pressure path downstream of the fluid pump and further located on the high pressure path between the recuperator and the heater , and a second portion of the fluid-drainage path being connected to the low-pressure path at the second connection point , the second connection point being located on the low-pressure path between the expander and the recuperator . an expander ; a recuperator ; a heater ; a fluid pump ; a working-fluid path including a high-pressure path for communicating pumped working fluid from the fluid pump toward the expander on a high-pressure side, and a low-pressure path for communicating the expanded working fluid away from the expander on a low-pressure side, the heat engine using a condensable working fluid, which, at least in part of the high-pressure path , is in the liquid phase, the high-pressure path at least extending between the recuperator and the expander via the heater , and the low-pressure path at least extending between expander and the recuperator ; characterised in that it further comprises a fluid-drainage path extending between a first connection point on the high-pressure path and a second connection point on the low-pressure path, the fluid drainage path being selectably open or closed for selectively draining working fluid from the high-pressure side toward the low-pressure side, a first portion of the fluid drainage path being connected to a portion of the high-pressure path , in which during normal operation the working fluid is mainly in the liquid phase, at the first connection point , the first connection point being located on the high pressure path downstream of the fluid pump and further located on the high pressure path between the recuperator and the heater , and a second portion of the fluid-drainage path being connected to the low-pressure path at the second connection point , the second connection point being located on the low-pressure path between the expander and the recuperator . <EOS>