A gas engine power plant comprising at least one dual fuel internal combustion engine configured to run by burning gas fuel, a cryogenic fuel storage for storing gas fuel in liquefied form for use of the engine, a fuel feed line between the cryogenic fuel storage and the at least one dual fuel internal combustion engine, a heat transfer circuit configured to circulate heat transfer fluid in the circuit for transferring heat from the at least one dual fuel engine to the heat transfer fluid, a main gas evaporator arranged to the fuel feed line and to the heat transfer circuit configured to evaporate the liquefied gas for use by the at least one dual fuel internal combustion engine, and a central heat transfer fluid cooler system arranged to the heat transfer circuit, characterized in that the central cooler system comprises a central cooler for cooling the heat transfer fluid and a first by-pass channel, arranged to the heat transfer circuit, and a flow control valve configured to control the flow of heat transfer fluid through the first by-pass channel and the central cooler, and the central cooler system comprises a valve actuator system arranged to operate the flow control valve, and the valve actuator system comprising a temperature probe in connection with the heat transfer circuit at the downstream side of the main gas evaporator, the actuator being configured to operate based on temperature information obtainable from the temperature probe and that the main gas evaporator is arranged into heat transfer communication with the heat transfer circuit after the central cooler and the first by-pass channel of the central cooler system in the flow direction of the heat transfer fluid such that heat transfer fluid temperature entering the main gas evaporator is controllable by the central cooler and the first by-pass channel of the central cooler system based on temperature of the heat transfer fluid at a location next after the main gas evaporator in the flow direction of the heat transfer fluid. at least one dual fuel internal combustion engine configured to run by burning gas fuel, a cryogenic fuel storage for storing gas fuel in liquefied form for use of the engine, a fuel feed line between the cryogenic fuel storage and the at least one dual fuel internal combustion engine, a heat transfer circuit configured to circulate heat transfer fluid in the circuit for transferring heat from the at least one dual fuel engine to the heat transfer fluid, a main gas evaporator arranged to the fuel feed line and to the heat transfer circuit configured to evaporate the liquefied gas for use by the at least one dual fuel internal combustion engine, and a central heat transfer fluid cooler system arranged to the heat transfer circuit, characterized in that the central cooler system comprises a central cooler for cooling the heat transfer fluid and a first by-pass channel, arranged to the heat transfer circuit, and a flow control valve configured to control the flow of heat transfer fluid through the first by-pass channel and the central cooler, and the central cooler system comprises a valve actuator system arranged to operate the flow control valve, and the valve actuator system comprising a temperature probe in connection with the heat transfer circuit at the downstream side of the main gas evaporator, the actuator being configured to operate based on temperature information obtainable from the temperature probe and that the main gas evaporator is arranged into heat transfer communication with the heat transfer circuit after the central cooler and the first by-pass channel of the central cooler system in the flow direction of the heat transfer fluid such that heat transfer fluid temperature entering the main gas evaporator is controllable by the central cooler and the first by-pass channel of the central cooler system based on temperature of the heat transfer fluid at a location next after the main gas evaporator in the flow direction of the heat transfer fluid.