AIR DISTRIBUTION CONTROL

• US 3,690,548 A
• Filed: 03/16/1971
• Issued: 09/12/1972
• Est. Priority Date: 03/16/1971
• Status: Expired due to Term

• Current Assignee: American Standard Companies Incorporated (Ideal Standard International Topco SCA)
• Original Assignee: 54601,, John C. Mcnabney
• Inventors: John C. McNabney, c/o The Trane Company, 54601,
• Primary Examiner(s): Edward J. Michael
• Application Number:
  US05/124,732
• Time in Patent Office: 546 Days
• Field of Search: 236/1C,49 165/22,28
• US Class Current: 236/1.00C
• CPC Class Codes: F24F 11/74 for controlling air flow rate or air velocity
• CPC Class Codes: F24F 11/76 by means responsive to temperature, e.g. bimetal springs
• CPC Class Codes: F24F 2110/30 Velocity

Abstract

An apparatus and method for limiting the flow in a variable air volume distribution system in which a sensed differential pressure provides a signal to increase or decrease air flow. Further circuitry is provided to allow the flow limiting means to properly function with seasonal changeovers.

Claims

1. An air distribution system for delivering conditioned air at a preselected substantially constant temperature to a plurality of zones wherein the temperature of each of said zones is controlled by varying the volume of conditioned air delivered to said zone, said system including ducts for carrying conditioned air from a source to at least one air terminal unit for delivering conditioned air to at least one of said zones, said unit including air throttling means for varying the volume of conditioned air delivered to said zone, said throttling means being normally responsive to a zone thermostat whereby said throttling means is caused to supply an increased volume of conditioned air in response to a first position of said thermostat, a duct temperature sensor, temperature responsive switch means in operative communication with said zone thermostat and said throttling means and responsive to said duct temperature sensor whereby said throttling means is caused to supply a decreased volume of conditioned air in response to said first position of said thermostat when the duct temperature rises above a preselected temperature;

means for sensing variations in the rate of air flow into said unit, pressure responsive means communicating with said sensing means and movable in response to changes in said rate of air flow, switch means actuated in response to the movement of said pressure responsive means to override said zone thermostat and said temperature responsive switch means when said rate of air flow exceeds a predetermined rate.

2. The apparatus according to claim 1 wherein said air throttling means includes a motor driven blade damper.

3. The apparatus according to claim 2 including two coaxially mounted electric motors, one of said motors driving said damper in a first direction and the other of said motors driving said damper in the opposite direction.

4. The apparatus according to claim 1 wherein said temperature responsive switch means includes a pair of interconnected snap-action switches in operative communication with said duct temperature sensor.

5. The apparatus according to claim 4 wherein each of said snap-action switches have a common contact, a normally closed contact, and a normally open contact, said normally closed contact of each switch being electrically connected to the normally open contact of the other switch.

6. The apparatus according to claim 5 wherein said normally closed contacts become open and said normally open contacts become closed at a predetermined temperature as sensed by said duct temperature sensor.

7. An air distribution system comprising in combination:

a. a central source of conditioned air;

b. duct means connecting a plurality of zones with said central source;

c. at least one air terminal box communicating with each of said zones;

d. damper means in at least one of said terminal boxes, said damper means being openable and closeable to vary the volume of air passing from said terminal box to said zone;

e. motor means drivingly connected to said damper means to open and close said damper means;

f. temperature responsive means in said zone to control said motor means wherein said motor means normally drives said damper means toward an opened position upon an increase in temperature in said zone;

g. switch means operably connecting said motor means and said temperature responsive means and including duct temperature sensing means, said switch means causing said motor means to drive said damper means toward an opened position upon a decrease in temperature in said zone when said duct temperature sensing means senses a temperature above a preset limit;

h. means for sensing the air flow rate into said terminal box, i. said sensing means communicating with pressure responsive means movable in response to changes in said air flow rate to override said temperature responsive means when said air flow rate exceeds a predetermined maximum rate.