A method of heating a liquefied stream, comprising: - passing the liquefied stream that is to be heated through a first heat transfer zone comprising a first box in the form of a shell that contains a heat transfer fluid, in indirect heat exchanging contact with the heat transfer fluid across a first heat transfer surface arranged inside the first box, whereby heat transfers from the heat transfer fluid to the liquefied stream, thereby condensing at least part of the heat transfer fluid to form a condensed portion; - allowing accumulation of a part of the condensed portion within the first box thereby forming a liquid layer of the heat transfer fluid in the liquid phase within the first box, wherein above the liquid layer of the heat transfer fluid in liquid phase within the first box is a vapour zone, whereby the first heat transfer surface is arranged within the vapour zone in the first box; - cycling the heat transfer fluid in a closed circuit from the first box via at least a downcomer to a second heat transfer zone and back to the first heat transfer zone, all arranged in an ambient; wherein said cycling of the heat transfer fluid comprises drawing liquid from the liquid layer in the first box and passing said liquid from the liquid layer in liquid phase through the downcomer to the second heat transfer zone, and passing the heat transfer fluid through the second heat transfer zone to the first heat transfer zone, characterised in that the heat transfer fluid in the second heat transfer zone indirectly heat exchanges with the ambient thereby passing heat from the ambient to the heat transfer fluid and vaporizing the heat transfer fluid, wherein the second heat transfer zone discharges into the vapour zone in first box at a location that is gravitationally above the liquid layer wherein the heat transfer fluid from the second heat transfer zone passes through open ends of one or more riser end pieces as the heat transfer fluid is being discharged from the second heat transfer zone into the first box, which one or more riser end pieces traverse through the liquid layer into the vapour zone, whereby the open ends of the riser end pieces are located gravitationally lower than the first heat exchange surface. - passing the liquefied stream that is to be heated through a first heat transfer zone comprising a first box in the form of a shell that contains a heat transfer fluid, in indirect heat exchanging contact with the heat transfer fluid across a first heat transfer surface arranged inside the first box, whereby heat transfers from the heat transfer fluid to the liquefied stream, thereby condensing at least part of the heat transfer fluid to form a condensed portion; - allowing accumulation of a part of the condensed portion within the first box thereby forming a liquid layer of the heat transfer fluid in the liquid phase within the first box, wherein above the liquid layer of the heat transfer fluid in liquid phase within the first box is a vapour zone, whereby the first heat transfer surface is arranged within the vapour zone in the first box; - cycling the heat transfer fluid in a closed circuit from the first box via at least a downcomer to a second heat transfer zone and back to the first heat transfer zone, all arranged in an ambient;