Vapor generating and recovering apparatus

In a vapor generating and recovery apparatus for vaporizing a liquid and condensing a vapor, including a housing comprising at least one compartment therein, said compartment having a liquid therein, the improvement comprising:

• heating and cooling system in heat transfer relation with said liquid and said vapor in said compartment, said system including a main condenser in heat emitting relation with said liquid;
• a main evaporator in heat absorbing relation with said vapor;
• a complementary condenser in heat emitting relation in said system disposed outside said compartment;
• and, means to compress a refrigerant flowing in said system, said means to compress being in fluid communication on its high pressure side with said main condenser and said complementary condenser, and on its low pressure side with said main evaporator, said system including expansion means disposed between said main condenser and said main evaporator, pump down valve means therein disposed downstream of said main condenser and upstream of said main evaporator selectively closed prior to the shut down of the compressor and remains closed during system pump down while simultaneously said means to compress continues to operate for pumping refrigerant out of said compressor, and means to de-activate said means to compress at preselected refrigerant conditions said means to de-activate being operatively connected to said means to compress.