circuit 8 the pump 26 conveys coolant through the engine block 4 and the cooling circuit 8 in order to achieve the quickest possible warming up of the internal combustion engine 2 the further thermostatic valve 24 in the further bypass line 22 is largely opened up to a temperature of for example 85 u00b0 c so that the coolant circumventing the first heat exchanger 11 heats up quickly the further thermostatic valve 24 thereby guides and the bypass line 20 further guides a partial quantity of the coolant flow to the first heat exchanger 11 the thermostatic valve 21 mixes hot coolant flowing through the bypass line 20 and coolant cooled by the first heat exchanger 11 to a temperature of 70 u00b0 c for example if the temperature of 85 u00b0 c is exceeded the further thermostatic valve 24 closes and the predominant part of the coolant flows to cool the internal combustion engine 2 through the first heat exchanger 11 nevertheless even in this operating state the thermostatic valve 21 mixes hot coolant flowing through the bypass line 20 and coolant cooled by the first heat exchanger 11 the condenser 16 is thus flowed through over a wide operating range of the internal combustion engine 2 by coolant at a largely constant temperature of 70 u00b0 c for example an overcooling of the working fluid of the device for heat recovery 10 is avoided the tempered coolant flowing out of the thermostatic valve 21 flows.