A heating and/or cooling temperature adjusting apparatus disposed proximate a point of use comprising a heat exchange structure, at least one thermal mass unit comprised of a material which changes phase at a predetermined temperature, and a housing which at least partially encloses the heat exchange structure and thermal mass unit. Additionally, a plurality of thermal mass units can be employed, each with equivalent, or differing, temperature threshold points for conversion between solid, liquid or gaseous phases. The presence of the thermal mass unit at the point of use allows for the heating/cooling system to rapidly adjust the temperature of the room while simultaneously decreasing the duty cycle of the heating/cooling generator (e.g. boiler).