Abstract: The gas exchange termination assembly overcomes the affects of fluid turbulence caused by wind, drafts, and air pressure. The invention can be applied to gas burning devices under 4,000 BTU input. Turbulent flow of gases at the gas exchange termination assembly are mitigated by the location of slots and openings in the gas exchange termination assembly for both intake air and exhaust gases. The gas exchange termination assembly is connected, coaxially through the building structural wall, to a sealed combustion system in order that all gases are drawn from and return to the same general location (directly) outside the building. The gas exchange termination assembly includes an intake air hood for intake air with additional intake air openings, an exhaust pipe with slots and a plug to move products of combustion at angles to the concentric pipe as the intake and exhaust gases enter and exit.

Abstract: The gas exchange termination assembly overcomes the affects of fluid turbulence caused by wind, drafts, and air pressure. The invention can be applied to gas burning devices under 4,000 BTU input. Turbulent flow of gases at the gas exchange termination assembly are mitigated by the location of slots and openings in the gas exchange termination assembly for both intake air and exhaust gases. The gas exchange termination assembly is connected, coaxially through the building structural wall, to a sealed combustion system in order that all gases are drawn from and return to the same general location (directly) outside the building. The gas exchange termination assembly includes an intake air hood for intake air with additional intake air openings, an exhaust pipe with slots and a plug to move products of combustion at angles to the concentric pipe as the intake and exhaust gases enter and exit.

Abstract: A cascade refrigeration system includes an evaporator unit (10, 12) located adjacent a test chamber and remote from the refrigeration system. A conduit (38) carries refrigerant from the cascade refrigeration system to the evaporator unit (10, 12). The liquid refrigerant passed through an expansion valve (28) to meter the refrigerant to delivery to the evaporator unit (10, 12). Spent refrigerant exiting the evaporator unit is returned to the cascade refrigeration system by a return line (40). In order to maintain a constant liquid refrigerant flow to the expansion valve so as to enable the refrigeration system to cool the chamber as needed, liquid refrigerant is bypassed around the evaporator unit (10, 12) and to the return line (40). The bypass circuit includes a control valve (162) which selectively diverts liquid refrigerant to the return line (40) during low-demand conditions at the evaporator unit (10, 12), thus maintaining a constant supply of liquid at the expansion valve.