Mixed air temperature sensor bypass

Patent metadata

Field	Value
Publication number	US-9581350-B2
Application number	US-201414219306-A
Country	US
Kind code	B2
Filing date	Mar 19, 2014
Priority date	Oct 29, 2013
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

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.

First claim

We claim:

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 the 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 7 , 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.

Assignees

• Lennox Ind Inc

Inventors

• Troxell Marcus
• Renker Michael

Classifications

• F24F2110/12

  of the outside air · CPC title

• F24F11/30

  for purposes related to the operation of the system, e.g. for safety or monitoring · CPC title

• F24F2110/10

  Temperature · CPC title

• F24F2011/0006

  using low temperature external supply air to assist cooling · CPC title

• F24F11/70 Primary

  Control systems characterised by their outputs; Constructional details thereof · CPC title