Use the smaller blower and attach this to a 1" flex tube which should be routed inside an approx. 3" tube all the way up into the dispensing tower stopping just below the shanks. This will assure that the cold air is forced into the tower and has a path to return to kegerator. Be certain that air is not escaping anywhere. This will diminish the efficiency of the refrigeration. This is not recommended for lengths longer than this due to overworking the refrigerator's capabilities.
Scott Zuhse, Instructor
Micro Matic Dispense Institute