Method and system for controlling an economizer
First Claim
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1. A system for conditioning air in a plurality of zones, comprising:
- a heating, ventilating, and air conditioning unit having an economizer operable to allow variable amounts of outdoor air into the unit, the unit operable to provide conditioned air to one or more zones;
a supply air duct connecting said unit to said one or more zones;
a damper associated with each of said one or more zones, the damper operable to control the amount of conditioned air entering each of said one or more zones;
a return air duct connecting each of said one or more zones to said unit and returning air to said unit;
a bypass duct connecting the supply duct to the return duct;
a first temperature sensor for sensing a first temperature representative of the air returned to said unit;
a second temperature sensor for sensing a second temperature representative of the outdoor air; and
a main control, coupled with said temperature sensors, operable to modulate the economizer to increase the amount of outdoor air entering said unit when the first temperature falls below a cooling setpoint, the second temperature is greater than the first temperature, and the unit is operating in a cooling mode, the control further operable to modulate the economizer to increase the amount of outdoor air entering said unit when the first temperature rises above a heating setpoint, the second temperature is less than the first temperature, and the unit is operating in a heating mode.
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Abstract
A method and system for controlling the temperature of air returned to a conditioning unit in a zoned system is disclosed. The system includes a heating, ventilating, and air conditioning (HVAC) unit that has an economizer. The HVAC unit is connected to a plurality of zones by a supply duct and a return duct. A temperature sensor is provided to sense the temperature of air returning to the HVAC unit. A main control increases the amount of outdoor air entering the system through the economizer when the temperature of the returned air is excessively warm or excessively cold.
56 Citations
24 Claims
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1. A system for conditioning air in a plurality of zones, comprising:
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a heating, ventilating, and air conditioning unit having an economizer operable to allow variable amounts of outdoor air into the unit, the unit operable to provide conditioned air to one or more zones;
a supply air duct connecting said unit to said one or more zones;
a damper associated with each of said one or more zones, the damper operable to control the amount of conditioned air entering each of said one or more zones;
a return air duct connecting each of said one or more zones to said unit and returning air to said unit;
a bypass duct connecting the supply duct to the return duct;
a first temperature sensor for sensing a first temperature representative of the air returned to said unit;
a second temperature sensor for sensing a second temperature representative of the outdoor air; and
a main control, coupled with said temperature sensors, operable to modulate the economizer to increase the amount of outdoor air entering said unit when the first temperature falls below a cooling setpoint, the second temperature is greater than the first temperature, and the unit is operating in a cooling mode, the control further operable to modulate the economizer to increase the amount of outdoor air entering said unit when the first temperature rises above a heating setpoint, the second temperature is less than the first temperature, and the unit is operating in a heating mode. - View Dependent Claims (2, 3, 4, 5)
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6. A control system a heating, ventilating and air conditioning unit in a system having a plurality of zones, each of the plurality of zones connected to said unit by a supply duct and a return duct, the system comprising:
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an economizer;
a first temperature sensor for sensing a first temperature representative of the air returned to said unit;
a second temperature sensor for sensing a second temperature representative of the outdoor air; and
a control device operable to modulate the economizer to increase the amount of outdoor air entering said unit when the first temperature falls below a cooling setpoint, the second temperature is greater than the first temperature, and the unit is operating in a cooling mode, the control further operable to modulate the economizer to increase the amount of outdoor air entering said unit when the first temperature rises above a heating setpoint, the second temperature is less than the first temperature, and the unit is operating in a heating mode. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A system for conditioning air in a plurality of zones, comprising:
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an air conditioning unit having an economizer operable to allow variable amounts of outdoor air into the unit, the unit operable to provide cooled air to one or more zones;
a supply air duct connecting said unit to said one or more zones;
a return air duct connecting each of said one or more zones to said unit and returning air to said unit;
a first temperature sensor for sensing a first temperature representative of the air returned to said unit;
a second temperature sensor for sensing a second temperature representative of the outdoor air; and
a control device, coupled with said temperature sensors, operable to modulate the economizer to increase the amount of outdoor air entering said unit when the first temperature falls below a cooling setpoint and the second temperature is greater than the first temperature, the modulation of the economizer operable to increase the temperature of the air returned to said unit. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A system for conditioning air in a plurality of zones, comprising:
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an air heating unit having an economizer operable to allow variable amounts of outdoor air into the unit, the unit operable to provide heated air to one or more zones;
a supply air duct connecting said unit to said one or more zones;
a return air duct connecting each of said one or more zones to said unit and returning air to said unit;
a first temperature sensor for sensing a first temperature representative of the air returned to said unit;
a second temperature sensor for sensing a second temperature representative of the outdoor air; and
a control device, coupled with said temperature sensors, operable to modulate the economizer to increase the amount of outdoor air entering said unit when the first temperature is above a heating setpoint and the second temperature is less than the first temperature, the modulation of the economizer operable to decrease the temperature of the air returned to said unit. - View Dependent Claims (21, 22, 23, 24)
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Specification