HVAC system having a diagnostics controller associated therewith

Patent metadata

Field	Value
Publication number	US-10061330-B2
Application number	US-201313919590-A
Country	US
Kind code	B2
Filing date	Jun 17, 2013
Priority date	Dec 21, 2011
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

In one aspect, the present disclosure provides a controller for a HVAC system having an economizer with a damper and pressure sensors on opposing sides of the economizer. The controller comprise a diagnostics controller having a program configured to use pressure difference sensor data to determine if a pressure difference across the economizer is outside an operational design parameter of the HVAC system, and generate an error signal when the pressure difference is outside the operational design parameter.

First claim

What is claimed is:

1. A controller for a heating, ventilating and cooling (HVAC) system having an economizer with a damper and pressure sensors on opposing sides of said economizer, comprising;
a diagnostics controller having a program configured to:
use pressure difference sensor data and damper position data of said economizer to determine if a pressure difference across said economizer of said HVAC system is outside an operational design parameter of said HVAC system, wherein said operational design parameter is a function of a damper position of said economizer, and
generate an error signal indicating a return restriction problem when said pressure difference is outside said operational design parameter and said damper position is lower than a predetermined position, wherein said error signal specifies which one or more of the following conditions caused the return restriction problem: a duct restriction, an incorrect damper position, or a pressure sensor malfunction;
wherein said diagnostics controller is configured with a stored diagnostics data table relating said pressure differences sensor data with said damper position data, and wherein said diagnostics controller is configured to:
check pressure differences across said economizer at different damper positions during a continuous operation of said HVAC system, based on said stored diagnostics data table; and
use a persistence criterion routine to ensure that a fault persists before triggering said error signal during said continuous operation of said HVAC system.

2. The controller in claim 1 , wherein said diagnostics controller is configured to receive said damper position data from a HAVC system ventilation director.

3. The diagnostics controller recited in claim 1 , wherein said diagnostics controller is configured to check pressure differences across said economizer at different damper positions during a calibration period of said HVAC system, based on said stored diagnostics data table.

4. The diagnostics controller recited in claim 1 , wherein said stored diagnostics data table relates a damper position of 0%, 50%, and 100% to low limits of 0.05 h2o, 0.05 h2o, 0.0 h2o and high limits of 0.60 h2o, 0.25 h2o and 0.20 h2o, respectively.

5. A heating, ventilating and cooling (HVAC) system, comprising:
an economizer having a damper and an actuator to move blades thereof;
a pressure sensor configured to determine a pressure difference across said damper; and
a diagnostics controller having a program stored thereon configured to:
use pressure difference sensor data and damper position data of said economizer to determine if said pressure difference across said economizer is outside an operational design parameter of said HVAC system, wherein said operational design parameter is a function of a damper position of said economizer, and
generate an error signal indicating a return restriction problem when said pressure difference is outside said operational design parameter and said damper position is lower than a predetermined position, wherein said error signal specifies which one or more of the following conditions caused the return restriction problem: a duct restriction, an incorrect damper position, or a pressure sensor malfunction;
wherein said diagnostics controller is configured with a stored diagnostics data table relating said pressure difference sensor data with said damper position data, and wherein said diagnostics controller is configured to:
check pressure differences across said economizer at different damper positions during a continuous operation of said HAVC system ; and
use a persistence criterion routine to ensure that a fault persists before triggering said error signal during said continuous operation.

6. The HAC system recited in claim 5 , wherein said damper position data is based on a blade angle data of said economizer.

7. The HVAC system recited in claim 6 , wherein said HVAC system further comprises a ventilation director associated with said actuator and said diagnostics controller is configured to receive said damper position data from said ventilation director.

8. The HVAC system recited in claim 5 , wherein said diagnostics controller is configured to check pressure differences across said economizer at different damper positions during a calibration period of said HVAC system, based on said stored diagnostics data table.

9. The HVAC system recited in claim 5 , wherein said stored diagnostics data table relates a damper position of 0%, 50%, and 100% to low limits of 0.05 h2o, 0.05 h2o, 0.0 h2o and high limits of 0.60 h2o, 0.25 h2o and 0.20 h2o, respectively.

Assignees

• Lennox Ind Inc

Inventors

• Douglas Jonathan
• Thomas Herman M

Classifications

• F24F11/30 Primary

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

• F24F2110/30

  Velocity · CPC title

• F24F2140/40

  Damper positions, e.g. open or closed · CPC title

• F24F11/52

  Indication arrangements, e.g. displays · CPC title

• G05D23/00 Primary

  Control of temperature · CPC title