HVAC controller with HVAC system failure detection

Patent metadata

Field	Value
Publication number	US-10747243-B2
Application number	US-201113325315-A
Country	US
Kind code	B2
Filing date	Dec 14, 2011
Priority date	Dec 14, 2011
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

An HVAC controller that monitors a current performance level of an HVAC system, and determines if the current performance level falls below a minimum performance threshold level for at least a first predetermined amount of time. The HVAC controller may be configured it display an alert on the display of the HVAC controller if the HVAC controller determines that the current performance level has fallen below the minimum performance threshold level for at least the first period of time. In some cases, the HVAC controller may remove the alert from the display of the HVAC controller if the current performance level subsequently rises and remains above the minimum performance threshold level for at least a second predetermined amount of time. In some cases, the first predetermined amount of time may include a utility shutoff period component and/or a defrost cycle period component.

First claim

What is claimed is:

1. An HVAC controller configured to control one or more components of an HVAC system that has a blower for supplying air from a return air duct to a supply air duct through an air-to-air heat exchanger, the HVAC controller comprising:
a user interface including a display;
a memory;
an I/O block configured to receive one or more signals from the HVAC system and configured to provide one or more control signals to the HVAC system;
a controller coupled to the memory, the user interface, and the I/O block, the controller configured to:
monitor one or more signals received via the I/O block that are related to a current performance level of the HVAC system, wherein the current performance level is based, at least in part, on a current delta T value across the air-to-air heat exchanger of the HVAC system that is derived from the one or more signals, wherein the current delta T value represents a difference between a return air temperature from the return air duct prior to passage through the heat exchanger and a discharge air temperature from the supply air duct after passage through the heat exchanger;
determine if the current performance level of the HVAC system falls and remains below a minimum performance level for at least a first predetermined amount of time, the controller configured to repeatedly update if the current performance level of the HVAC system remains below the minimum performance level for at least the first predetermined amount of time, wherein the minimum performance level of the HVAC system is based, at least in part, on a pre-determined minimum delta T limit across the air-to-air heat exchanger, wherein the pre-determined minimum delta T limit is stored in the memory;
display an alert on the display of the HVAC controller if the controller determines that the current performance level has fallen and remained below the minimum performance level for at least the first predetermined amount of time; and
control the HVAC system based at least in part on one or more of the signals received via the I/O block.

2. The HVAC controller according to claim 1 , wherein the controller removes the alert from the display of the HVAC controller if the current performance level subsequently rises and remains above the minimum performance level for at least a second predetermined amount of time.

3. The HVAC controller according to claim 2 , wherein the first predetermined amount of time is different from the second predetermined amount of time.

4. The HVAC controller according to claim 1 , wherein the first predetermined amount of time comprises a utility shutoff period component.

5. The HVAC controller according to claim 1 , wherein the first predetermined amount of time comprises a defrost cycle period component.

6. The HVAC controller according to claim 1 , wherein the HVAC system includes two or more stages, and wherein respective first predetermined amounts of time are stored in the memory of the HVAC controller for each of at least two stage combinations of the two or more stages.

7. The HVAC controller according to claim 6 , wherein the controller of the HVAC system retrieves from the memory and then uses the particular first predetermined amount of time that corresponds to the currently active stage combination.

8. The HVAC controller according to claim 1 , wherein the controller determines if the current performance level of the HVAC system falls and remains below the minimum performance level for at least the first predetermined amount of time during a single cycle of the HVAC system.

9. The HVAC controller according to claim 1 , wherein the HVAC system comprises a forced air furnace, and the air-to-air heat exchanger is part of the forced air furnace.

10. The HVAC controller according to claim 1 , wherein the controller records the alert in a log stored in the memory of the HVAC controller.

11. A method of monitoring operation of an HVAC system that includes a blower for supplying air from a return air duct to a supply air duct through an air-to-air heat exchanger, the HVAC system including one or more HVAC components that are controlled, at least in part, by an HVAC controller having a user interface with a display, a memory, a controller, and an I/O block configured to receive one or more signals from the HVAC system and configured to provide one or more control signals to the HVAC system, the method comprising:
receiving, by the I/O block of the HVAC controller, one or more signals from the HVAC system that are related to a current performance level of the HVAC system, wherein the current performance level is based, at least in part, on a current delta T value across the air-to-air heat exchanger of the HVAC system that is derived from the one or more signals from the HVAC system, wherein the current delta T value represents a difference between a return air temperature from the return air duct prior to passage through the heat exchanger and a discharge air temperature from the supply air duct after passage through the heat exchanger;
repeatedly updating, by the controller, the current performance level of the HVAC system over time to determine an amount of time that the current performance level of the HVAC system falls and remains below a minimum performance level, wherein the minimum performance level of the HVAC system is based, at least in part, on a pre-determined minimum delta T limit across the air-to-air heat exchanger, wherein the pre-determined minimum delta T limit is stored in the memory;
comparing, by the controller, the amount of time the current performance level of the HVAC system remains below the minimum performance level to a first predetermined amount of time that is stored in the memory;
determining, by the controller, that the current performance level of the HVAC system is below the minimum performance level for at least the first predetermined amount of time and displaying an alert on the display of the HVAC controller in response to determining that the current performance level of the HVAC system is below the minimum performance level for at least the first predetermined amount of time; and
controlling, by the controller, the HVAC system based at least in part on one or more of the signals received via the I/O block.

12. The method according to claim 11 , further comprising:
determining, by the controller, that the current performance level subsequently rises and remains above the minimum performance level for at least a second predetermined amount of time; and
removing, by the controller, the alert from the display of the HVAC controller in response to determining that the current performance level subsequently rises and remains above the minimum performance level for at least the second predetermined amount of time.

13. The method according to claim 12 , wherein the first predetermined amount of time is different from the second predetermined amount of time.

14. The method according to claim 11 , wherein the first predetermined amount of time comprises a utility shutoff period component.

15. The method according to claim 11 , wherein the first predetermined amount of time comprises a defrost cycle period component.

16. The method according to claim 11 , wherein the HVAC system includes two or more stages, and wherein respective first predetermined amounts of time are stored in the memory of the HVAC controller for each of at least two stage combinations of the two or more stages.

17. The method according to claim 16 , further comprising, retrieving, by the controller and from the memory, the particular first pred

Assignees

• Barton Eric
• Leen Cary
• Zywicki Stan
• Schultz David
• Aljabari Mohammad
• Ademco Inc

Inventors

• Barton Eric
• Leen Cary
• Zywicki Stan
• Schultz David
• Aljabari Mohammad

Classifications

• G05D23/1902 Primary

  characterised by the use of a variable reference value · CPC title