MIXED AIR TEMPERATURE SENSOR BYPASS

• US 20150114614A1
• Filed: 03/19/2014
• Published: 04/30/2015
• Est. Priority Date: 10/29/2013
• Status: Active Grant

• Current Assignee: Lennox Industries Incorporated (Lennox International Incorporated)
• Original Assignee: Lennox Industries Incorporated (Lennox International Incorporated)
• Inventors: Renker, Michael, Troxell, Marcus
• Granted Patent: US 9,581,350 B2
• Time in Patent Office: Days
• US Class Current: 165/250
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/70 Control systems characterised by their outputs; Constructional details thereof
• CPC Class Codes: F24F 11/81 by controlling the air supply to heat-exchangers or bypass channels
• CPC Class Codes: F24F 2011/0006 using low temperature external supply air to assist cooling
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2110/12 of the outside air

Abstract

In an embodiment, a circuit for providing a mixed air temperature signal is provided. The circuit has a temperature input to an economizer controller, an air temperature sensor, a false air temperature device, and a switching device. The switching device has a switch and a switch actuating device. The switch connects the temperature input to the air temperature sensor when the switch is in a first state. The switch connects the temperature input to the false air temperature device when the switch is in a second state. The switch actuating device places the switch in the first state when a mechanical cooling signal is not sent. The switch actuating device places the switch in the second state when the mechanical cooling signal is sent.

Claims

1. A circuit for providing a mixed air temperature signal, the circuit comprising:

a temperature input to an economizer controller;

an air temperature sensor;

a false air temperature device; and

a switching device comprising;

a switch, the switch configured to;

connect the temperature input to the air temperature sensor when the switch is in a first state; and

connect the temperature input to the false air temperature device when the switch is in a second state; and

a switch actuating device, the switch actuating device configured to;

place the switch in the first state when a mechanical cooling signal is not sent; and

place the switch in the second state when the mechanical cooling signal is sent.

2. The circuit of claim 1, wherein the mechanical cooling signal is sent from the economizer controller to a unit, the unit comprising an air conditioning function.

3. The circuit of claim 1, wherein:

the temperature input comprises a mixed air temperature input; and

the air temperature sensor comprises a mixed air temperature sensor.

4. The circuit of claim 1, wherein the false air temperature device comprises a resistor.

5. The circuit of claim 1, wherein:

the switching device comprises a relay; and

the switch actuating device comprises an inductor positioned to energize the relay when the mechanical cooling signal is sent.

6. The circuit of claim 1, wherein:

the economizer controller controls an economizer of a unit;

the unit comprises an economizer, an evaporator coil, and the air temperature sensor; and

the evaporator coil is between the air temperature sensor and the economizer.

7. The circuit of claim 1, wherein:

the temperature input comprises a first terminal and a second terminal;

when connected to the temperature input, the air temperature sensor produces a voltage drop across the temperature input; and

when connected to the temperature input, the resistor produces a voltage drop across the temperature input.

8. The circuit of claim 6, wherein:

the economizer controller comprises a mixed air set-point; and

the voltage drop produced by the resistor represents a temperature greater than or equal to the mixed air set-point.

9. A method for providing a mixed air temperature signal, the method comprising:

receiving a mechanical cooling signal; and

in response to the mechanical cooling signal;

disconnecting a temperature input from an air temperature sensor, the temperature input comprising a temperature input to an economizer controller; and

connecting a temperature input to a false air temperature device.

10. The method of claim 9, further comprising:

receiving an end to the mechanical cooling signal; and

in response to end to the mechanical cooling signal;

disconnecting the temperature input from the false air temperature device; and

connecting the temperature input to the air temperature sensor.

11. The method of claim 9, wherein the mechanical cooling signal is sent from the economizer controller to a unit, the unit comprising an air conditioning function.

12. The method of claim 11, wherein receiving the mechanical cooling signal comprises an inductor intercepting the mechanical cooling signal.

13. The method of claim 9, wherein:

the temperature input comprises a mixed air temperature input; and

the air temperature sensor comprises a mixed air temperature sensor.

14. The method of claim 9, wherein the false air temperature device comprises a resistor.

15. The method of claim 9, wherein:

the economizer controller controls an economizer of an a unit;

the unit comprises an economizer, an evaporator coil, and the air temperature sensor; and

the evaporator coil is between the air temperature sensor and the economizer.

16. The method of claim 9, wherein:

the temperature input comprises a first terminal and a second terminal;

when connected to the temperature input, the air temperature sensor produces a voltage drop across the temperature input; and

when connected to the temperature input, the resistor produces a voltage drop across the temperature input.

17. The method of claim 16, wherein:

the economizer controller comprises a mixed air set-point; and

the voltage drop produced by the resistor represents a temperature greater than or equal to the mixed air set-point.