The disclosure relates to a refrigerant device and a method for providing additional head to support a refrigeration liquid feed system. The refrigerating device comprises a refrigerant liquid container, a sinking conduit and a rising conduit, the sinking conduit extending downwardly to a connection with the rising conduit, the rising conduit extending upwardly from the connection with the sinking conduit. The refrigerating device further comprises an evaporator having an inlet connected downstream to the rising conduit and an outlet connected to the refrigerant liquid container via a return conduit, and a gas injector connected to the rising conduit, adapted to supply gas in order to allow gas to rise together with liquid refrigerant in the rising conduit, thereby reducing the total density of the mixture of liquid refrigerant and gas relative the density of liquid refrigerant.