Abstract: To prevent the rupturing, by the expansion of the water upon freezing, of a water-freezing ice-storing reservoir and at the same time release the warmer air after producing the freezing of the water into ice, the interior of the reservoir is surrounded by a duplex wall structure or anti-freeze barrier of highly insulating material, such as the expanded polystyrene plastic known commercially as styrofoam, in the form of slabs spaced inward from the tank wall by compression springs so that the inner body of water within the duplex insulating anti-freeze barrier is frozen by freezing the air entering that body through multiple pipes from the outside atmosphere in winter time while the outer body of water adjacent the tank wall of the reservoir but outside the insulating wall thereof is protected from freezing by the insulating effect of the slabs.

Abstract: An above-ground insulated tank adapted to be filled with water has a hollow upper wall with air ducts from which a first set of flexible air discharge pipes extends downward a short distance. Disposed near the bottom wall of the tank is a second set of perforated air discharge pipes of cruciform shape permitting air to bubble upward therefrom. A third set of unperforated flat-spirally-coiled air pipes is disposed beneath the second set and rests on the bottom of the tank and is composed of copper for high heat conductivity. Rising from the top wall of the tank and communicating therewith is an air inlet stack and an air outlet stack disposed side-by-side above, and in communication with, an air control housing containing three air chambers and provided with multiple motor-driven air blowers.