Abstract: A new and improved portable, immersible heat exchanger apparatus is provided for immersion into a quantity of material that is to cooled or heated. The apparatus includes a continuous copper tube assembly which is comprised of a straight, horizontal handle portion, a helically coiled immersion portion, and a vertically oriented, hook-shaped hanger portion. The top end of the immersion portion is connected to the handle portion; and the bottom end of the immersion portion is connected to the hanger portion. In use, the immersion portion is immersed in the material that is to undergo heat exchange. Tap water from a faucet is passed through the tube assembly to serve as a medium for heat exchange. The water enters the tube assembly at the handle portion, runs through the handle portion, the immersion portion, and the hanger portion, and exits from the end of the hanger portion. A flexible hose connects the handle portion to the water faucet.