the primary vapor hot gas refrigerant transport line 1 which is located between the first supplemental vapor refrigerant line 18 entering into the air source heat exchanger 4 in the cooling mode and the supplemental liquid refrigerant line 19 exiting from out of the supplemental air source heat exchanger hlhd 4 in the cooling mode so that the refrigerant flow is forced through the hlhd 4 in the cooling mode but can travel directly though the primary vapor transport line 1 in the heating mode not shown herein where the refrigerant would be traveling in a reverse direction as depicted herein in the cooling mode of operation without traveling through the supplemental air source heat exchanger hlhd 4 at all and effectively by passing the hlhd 4 a second check valve 17 may be located within the second vapor refrigerant transport line 19 exiting the supplemental air source heat exchanger hlhd 4 in the cooling mode so as to prevent refrigerant flow through the air source heat exchanger hlhd 4 in the heating mode of operation as would be understood by those skilled in the art although not shown herein the first check valve 16 would be opened in the heating mode of operation and the second check valve 17 would be closed the opposite of the positions shown herein in an operative cooling mode by each respective valve 16 and 17 an unfinned u bend segment 33 of the finned refrigerant transport tubing 5 is shown connecting the finned tubing 5 within the exterior supplemental air source heat exchanger hlhd 4 the second vapor refrigerant transport line 19 exiting the supplemental air source heat exchanger hlhd 4 in the cooling mode is preferably a vapor refrigerant transport line 19 and not a smaller diameter liquid.