Abstract: A heat exchange apparatus for use in transferring heat to a heat sink. Preferably, the heat sink is comprised of a natural gas supply line at a pressure reduction station. Alternately, the heat sink is comprised of a storage tank. The apparatus is comprised of a heat exchange vessel, adapted to contain an amount of a heat exchange fluid, and a heat source. The heat exchange vessel includes a sump section at a lower end thereof, and a heat transfer section for transferring heat to the heat sink. The heat exchange vessel further includes a single communication junction between the sump section and the heat transfer section which provides fluid communication therebetween. The heat source is associated with the sump section and adapted to add heat to the heat exchange fluid in order to cause the heat exchange fluid to evaporate in the heat exchange vessel.