Abstract: Apparatus for and method of use for a heat exchanger in an HVAC system having a system refrigerant for heat transfer between a radiator and a heat exchanger, in heat transfer communication through the heat exchanger. Single or multiple heat exchange loops and flow controllers maintain system balance during operation of the system.

Abstract: An audio speaker is incorporated in a ventilation register having a front grill through which sound generated by the audio speaker is projected, and a back plate to which the audio speaker is secured, spaced apart from the front grill by side plates to form an enclosure adapted to be received in registration with the ventilation duct. The back plate includes at least one and preferably a plurality of ventilation slots offset from and surrounding the audio speaker for communicating an air flow between the front grill and the back plate of the speaker arrangement, thereby allowing for the unimpeded operation of the ventilation system. So as to provide thermal protection for sensitive components of the audio speaker, thermal barrier is installed over the rearward extending speaker components to thermally isolate those components from conditioned, heated and cooled air either being flowed into or out of the room.