Thermally powered diffuser

A thermally powered variable air volume diffuser that regulates air volume delivery in response to both air supply and room air temperature changes comprising:

• a diffuser housing for connection to an air supply duct and having an supply air inlet and a diffused air outlet;
• air flow outlet control means for varying the volume of air discharged from said diffused air outlet, said air flow outlet control means positioned relative to said diffuser housing so as to define an air discharge opening;
• a first thermal actuator positioned to be exposed primarily to supply air and thermoactively responsive only when warm supply air heats said first thermal actuator above a preselected response threshold temperature, said first thermal actuator operatively connected to said air flow outlet control means so as to increase the size of the discharge opening as the temperature of said first thermal actuator rises above its response threshold temperature;
• a second thermal actuator positioned to be exposed primarily to supply air and thermoactively responsive only when warm supply air heats said second thermal actuator to a temperature above a preselected response threshold temperature higher than the temperature at which said first thermal actuator responds, said second thermal actuator operatively connected to said air flow outlet control means so as to decrease the size of the discharge opening as the temperature of said second thermal actuator increases above its response threshold temperature;
• a third thermal actuator positioned to be exposed primarily to room air and thermoactively responsive only when the temperature of said third thermal actuator rises above a preselected response threshold temperature, said third thermal actuator operatively connected to said air flow outlet control means so as to decrease the size of the air discharge opening as the temperature of said third thermal actuator rises above the preselected response threshold temperature of said third thermal actuator;
• a fourth thermal actuator positioned to be exposed primarily to room air and thermoactively responsive only when heated above a preselected response threshold temperature when cool supply air has cooled said first, second, and third thermal actuators below their respective response temperature thresholds, said fourth thermal actuator operatively connected to said air flow outlet control means so as to increase the size of the discharge opening when heated above its response temperature threshold.