demand shaving is desired if temperature differentials or piping constraints limit the effectiveness of this thermal storage electrical load demand shifting configuration one or more low pressure blowers can be utilized to help move and pressurize the refrigerant vapor as it travels from the evaporator coils to the thermal storage condenser fig1 represents a schematic view of a typical prior art cooling only rtu 100 the figure shows the components relevant to the scope of this invention including refrigeration compressors 105 liquid and vapor refrigerant piping 110 amp 115 air cooled condenser coils 120 and condenser fans expansion devices 125 cooling evaporator coils 130 and overall rtu housing 135 heating components are often included in typical rtus of various types but heating sections are not required depending on the location and application and are not relevant to the scope of this invention and therefore are not illustrated in the figure air source heat pump rtus are relevant to the field of this invention and they are discussed in another figure fig1 represents a basic schematic diagram of the prior art of a conventional rtu 100 and is presented to serve as the basis against which the modifications pertaining to embodiments of the present invention can be clearly demonstrated in subsequent figures fig2 is a schematic of a retrofitted rtu 200 based on the rtu 100 of fig1 according to an.