Abstract: A variable air flow volume conditioned air distribution system of the kind having an air flow duct for supplying conditioned air to a room and a valve in the duct for regulating the volume of air flowing through the duct has a controller which senses the flow velocity in the duct and the room temperature in the room.The controller combines a temperature signal with a flow velocity signal through a velocity spring. A temperature change resets the flow velocity set point and produces a corresponding change in the volume flow through the duct.The controller includes an adjustable bias for the velocity spring for varying the rate of the velocity spring from a low spring rate for control at a low maximum permitted flow velocity in the duct to a higher spring rate for control at a higher permitted maximum flow velocity flow in the duct and vice versa.

Abstract: An air flow velocity controller in a variable air volume control system interlocks a room temperature signal from a thermostat with the velocity set point so that the velocity controller maintains a constantly regulated amount of air into a room in proportion to the room's thermostat demands and independent of variations in the static pressure in the duct.The controller includes a maximum lift cam and a movable spring fulcrum which are both mounted in a common cam housing to permit the maximum velocity setting to be adjusted for varying room requirements while maintaining a constant spring range regardless of the maximum velocity setting.The controller is constructed to provide automatic compensation for control offset produced by changes in the static air pressure in the duct.The controller includes the ability to control the air flow at a minimum velocity so that the air can be economically reheated or a minimum volume of air flow can be maintained for ventilation requirements.

Abstract: A dual duct variable volume air conditioning system has a first, cold duct for supplying cold air and a second, reset duct for supplying either hot air in a first mode of operation or cold air in a second mode of operation. A self-contained system regulator positions first and second valves in the first and second ducts in response to changes in room temperature. The regulator is effective to reverse the direction of response of the second valve to temperature in the second mode of operation from the direction of response of that valve to a similar temperature change in the first mode of operation so that the reset duct can be used as a hot duct with the system supplying warm or cold air on demand in the heating season (without mixing) and as a cold duct to double the cooling capacity of the system in the cooling season.

Abstract: A dual duct variable volume air conditioning system has a first, cold duct for supplying cold air and a second, reset duct for supplying either hot air in a first mode of operation or cold air in a second mode of operation. A self-contained system regulator positions first and second valves in the first and second ducts in response to changes in room temperature. The regulator is effective to reverse the direction of response of the second valve to temperature in the second mode of operation from the direction of response of that valve to a similar temperature change in the first mode of operation so that the reset duct can be used as a hot duct with the system supplying warm or cold air on demand in the heating season (without mixing) and as a cold duct to double the cooling capacity of the system in the cooling season.