METHODS AND SYSTEMS FOR MONITORING AN AIR FILTER OF AN HVAC SYSTEM

• US 20120323377A1
• Filed: 06/20/2011
• Published: 12/20/2012
• Est. Priority Date: 06/20/2011
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Hoglund, Steven, Bisson, Reed
• Granted Patent: US 10,119,718 B2
• Time in Patent Office: Days
• US Class Current: 700/277
• CPC Class Codes: B01D 46/0086 Filter condition indicators
• 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 11/39 Monitoring filter performance
• CPC Class Codes: F24F 11/52 Indication arrangements, e.g. displays

Abstract

Methods and systems for monitoring an air filter installed in an HVAC system may include operating the HVAC system in an air filter monitoring mode such as, for example, a fan only mode, and measuring, for example, a differential pressure across the air filter when the HVAC system is operating in the air filter monitoring mode. The method may include evaluating a status of the air filter using, for example, the measured differential pressure value, and in some cases, display the status on a display of an HVAC controller.

Claims

1. A method of monitoring a status of an air filter of an HVAC system, wherein the HVAC system has a number of controllable HVAC components, the method comprising:

placing the controllable HVAC components into a predetermined state;

while the controllable HVAC components are in the predetermined state;

measuring a first differential pressure value across the air filter;

determining a status of the air filter based at least in part on the measured first differential pressure value;

placing at least one of the controllable HVAC components into a different state other than the predetermined state, and operating the HVAC system while the at least one of the controllable HVAC components is in the different state;

after the HVAC system is operated with the at least one of the controllable HVAC components is in the different state, placing each of the controllable HVAC components back into the predetermined state; and

while the controllable HVAC components are in their predetermined state;

measuring a second differential pressure value across the air filter; and

determining the status of the air filter based at least in part on the measured second differential pressure value.

2. The method of claim 1, wherein the number of controllable HVAC components includes a fan and a heating element, and wherein the predetermined state of the fan is “

on” and

the predetermined state of the heating element is “

off”

.

3. The method of claim 2, wherein placing at least one of the controllable HVAC components into a different state other than the predetermined state includes turning the heating element “

on”

or changing a speed setting of the fan.

4. The method of claim 1, wherein the number of controllable HVAC components includes a fan and a cooling element, and wherein the predetermined state of the fan is “

on” and

the predetermined state of the cooling element is “

off”

.

5. The method of claim 4, wherein placing at least one of the controllable HVAC components into a different state other than the predetermined state includes turning the cooling element “

on”

or changing a speed setting of the fan.

6. The method of claim 1, wherein the number of controllable HVAC components includes a fan with a first non-zero fan speed and a second non-zero fan speed, and wherein the predetermined state of the fan is at the first non-zero fan speed.

7. The method of claim 6, wherein placing at least one of the controllable HVAC components into a different state other than the predetermined state includes changing the fan to the second non-zero fan speed.

8. The method of claim 1, wherein the number of controllable HVAC components includes a number of zone control dampers, and wherein the predetermined state of the number of zone control dampers is “

open”

.

9. The method of claim 8, wherein placing at least one of the controllable HVAC components into a different state other than the predetermined state includes closing at least one of the number of zone control dampers.

10. The method of claim 1, wherein the status of the air filter is determined by comparing the measured differential pressure values against a threshold differential pressure value.

11. The method of claim 10, wherein the threshold differential pressure value is determined by:

while the controllable HVAC components are in the predetermined state;

measuring a calibration differential pressure across a clean air filter;

determining the threshold differential pressure value based at least in part on the calibration differential pressure value.

12. The method of claim 10, wherein the threshold differential pressure value is determined by:

while the controllable HVAC components are in the predetermined state;

measuring a calibration differential pressure across an air filter that is at least partially blocked by some amount;

determining the threshold differential pressure value based at least in part on the calibration differential pressure value.

13. The method of claim 1, further comprising displaying the status of the air filter on a display of an HVAC controller.

14. An HVAC controller for controlling an HVAC system having a number of controllable HVAC components and an air filter, the HVAC controller comprising:

a controller;

a memory coupled to the controller;

a display coupled to the controller;

wherein the controller is configured to place each of the controllable HVAC components into a predetermined state, and while the controllable HVAC components are in the predetermined state, receive a measure related to an amount of flow restriction presented by the air filter of the HVAC system, and then determine a status of the air filter based at least in part on the received measure related to an amount of flow restriction presented by the air filter, and then placing at least one of the controllable HVAC components into a different state other than the predetermined state, and operating the HVAC system while the at least one of the controllable HVAC components is in the different state; and

the controller further configured to display the status of the air filter on the display.

15. The HVAC controller of claim 14, wherein the measure related to an amount of flow restriction presented by the air filter of the HVAC system is a differential pressure across the air filter.

16. The HVAC controller of claim 14, wherein the measure related to an amount of flow restriction presented by the air filter of the HVAC system is an air flow through the filter.

17. The HVAC controller of claim 14, wherein the predetermined state corresponds to a fan only mode.

18. The HVAC controller of claim 17, wherein the number of controllable HVAC components includes a number of zone control dampers, and wherein the predetermined state of the number of zone control dampers is “

open”

.

19. The HVAC controller of claim 14, wherein the controller is configured to repeatedly place each of the controllable HVAC components into the predetermined state, and while the controllable HVAC components are in the predetermined state, receives a measure related to an amount of flow restriction presented by the air filter of the HVAC system, and then determine a status of the air filter based at least in part on the received measure related to an amount of flow restriction presented by the air filter.

20. A method of monitoring a status of an air filter of an HVAC system of a building, wherein the HVAC system includes a number of controllable HVAC components, the method comprising:

operating the HVAC system in a normal operating mode to control a temperature in the building;

occasionally entering an air filter monitoring mode, wherein in the air filter monitoring mode, each of the controllable HVAC components is placed into a predetermined known state;

while in the air filter monitoring mode, receiving a measure related to an amount of flow restriction presented by the air filter, and determining a status of the air filter based at least in part on the received measure related to the amount of flow restriction presented by the air filter; and

displaying the status of the air filter on a display.