Abstract: The heat discharge of a refrigeration system, otherwise lost, is salvaged to pre-heat water, but in a manner which safeguards against possible contamination of the water by the refrigerant. To this end, the "closed" refrigeration system is duplicated by an equally "closed" water circulation system, and coils of each are disposed in heat exchange relation to enable the pre-heating of the water by the heat discharge of the refrigerant. Most significant, however, contamination would require that the refrigerant leak out of its coil through a defect therein and further pass into the water coil through a defect therein, a most unlikely occurrence.