Abstract: Improvements in the system for heating and cooling liquids as disclosed in prior U.S. Pat. No. 3,513,663. This prior system utilizes components of refrigeration such as a compressor, a condenser coil, an evaporator coil, a refrigerant, and expansion valve, in their well-known interrelationship and includes a first and second liquid source, which are pumped in heat-exchange fashion through segregated condenser and evaporator coils simultaneously with, and in the opposite direction to, that of the refrigerant. One broad improvement embodies the elimination of the second liquid source, typically a ground water well, and to alter normal liquid flow to achieve either heating or cooling. Another broad aspect of this invention is to optionally alter the path of both first and second liquid source flows in segregated heat-exchange fashion through the condenser and evaporator coils, whereby heating or cooling of either liquid source may be easily selected and controlled. Refrigerant flow may also be altered.