A circuit includes an evaporator receiving heat from a hot body; a condenser transmits heat to a cold body, a working fluid flows through a first conduit in vapour phase from the evaporator to the condenser, and flows through a second conduit in liquid phase, from the condenser to the evaporator. A first evaporator portion is in fluid communication with the second conduit and acts as a compensation chamber. A second evaporator portion is in fluid communication with the first conduit and contains the vapour phase. A porous wick moves the working fluid from the first evaporator portion to the second evaporator portion. A first flow controller interrupts or allows flow when fluid temperature in the elevator is respectively lower or higher than a first threshold. A second flow controller interrupts or allows flow when the temperature in the condenser is respectively higher or lower than a second threshold.