Self-balancing variable air volume heating and cooling system
First Claim
1. A method of automatically air balancing in a variable air volume system having a primary air supply comprising the steps of:
- providing a plurality of individual terminal units, each terminal unit located in a respective zone of a building and each terminal unit coupled to the primary air supply for controllably providing conditioned airflow into the corresponding zone of the building;
in each terminal unit, establishing a respective local cooling threshold temperature;
selecting a threshold load level of the primary air supply;
communicating to all of the terminal units an indication of the primary air supply load level;
in each terminal unit, determining a local zone temperature;
in each terminal unit, comparing the local zone temperature to the corresponding cooling threshold temperature; and
if said communicating step indicates that the primary air supply load level exceeds the threshold load level, in each terminal unit, reducing the terminal unit maximum airflow only if the corresponding local zone temperature is below the corresponding cooling threshold temperature, thereby rebalancing the cooling system such that zones having a local temperature below the local cooling threshold temperature are provided reduced airflow, thereby making increased airflow available to other zones in which the local temperatures exceed the local cooling threshold temperature.
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Accused Products
Abstract
A variable air volume heating and cooling system that provides automatic system-wide airflow balancing is disclosed. To balance the system, each terminal box maximum airflow setting is automatically and continuously adjusted in response to central supply fan loading conditions together with local zone conditions. The new system has the advantage of automating both initial air balancing of terminal units at the time of installation, as well as rebalancing to respond to changing conditions, without technician intervention. Substantial savings in energy cost can be achieved since the operating curve of each terminal unit is automatically adjusted to demand no more conditioned air volume than necessary.
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Citations
22 Claims
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1. A method of automatically air balancing in a variable air volume system having a primary air supply comprising the steps of:
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providing a plurality of individual terminal units, each terminal unit located in a respective zone of a building and each terminal unit coupled to the primary air supply for controllably providing conditioned airflow into the corresponding zone of the building; in each terminal unit, establishing a respective local cooling threshold temperature; selecting a threshold load level of the primary air supply; communicating to all of the terminal units an indication of the primary air supply load level; in each terminal unit, determining a local zone temperature; in each terminal unit, comparing the local zone temperature to the corresponding cooling threshold temperature; and if said communicating step indicates that the primary air supply load level exceeds the threshold load level, in each terminal unit, reducing the terminal unit maximum airflow only if the corresponding local zone temperature is below the corresponding cooling threshold temperature, thereby rebalancing the cooling system such that zones having a local temperature below the local cooling threshold temperature are provided reduced airflow, thereby making increased airflow available to other zones in which the local temperatures exceed the local cooling threshold temperature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A variable air volume terminal unit comprising:
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airflow input means for connection to a primary air supply (26); setpoint input means for receiving a temperature setpoint selected by a user; means for establishing an initial default unit airflow maximum; a space temperature sensor to provide an indication of a local zone temperature; an airflow modulating device (34); an airflow measuring device (32); a controller (36) for controlling the airflow modulating device to regulate airflow from the airflow input means through the terminal unit and coupled to the airflow measuring device for measuring airflow through the terminal unit; the controller including means for regulating airflow through the terminal unit in dependence upon the indicated local zone temperature, the temperature setpoint and the unit airflow maximum; means (40) coupled to the controller for receiving an indication of a primary air supply load level; the controller further including means for automatically adjusting the unit airflow maximum in dependence upon the indicated zone temperature and the indicated primary air supply load level. - View Dependent Claims (18, 19)
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20. A VAV system comprising:
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a primary supply system for providing a supply of conditioned airflow; a plurality of terminal units each serving a respective zone, each of the terminal units coupled to receive a supply of conditioned airflow from the primary supply system; a communications link interconnecting the primary supply system and at least one of the terminal units, the communications link adapted to transmit to the said at least one terminal unit an indication of a primary supply system load level; and means in the said at least one terminal unit for adjusting the unit maximum airflow in dependence upon the corresponding zone temperature and the indicated primary system load. - View Dependent Claims (21, 22)
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Specification