Detecting and handling a blocked condition in the coil

Patent metadata

Field	Value
Publication number	US-10168067-B2
Application number	US-201514861314-A
Country	US
Kind code	B2
Filing date	Sep 22, 2015
Priority date	Sep 22, 2015
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

A heating, ventilation, and air-conditioning (HVAC) system comprises an outdoor unit with a fan and a coil, and a controller communicatively coupled to the fan and coil. The controller is operable to receive feedback data from the fan, where the feedback data from the fan corresponds to a power and a speed of the fan. The controller is further operable to store a fan model and a plurality of thresholds and determine a virtual sensor measurement, based at least in part upon the feedback data from the fan and the fan model. The controller is operable to determine that the virtual sensor measurement is greater than a frost threshold or a fouling threshold. The controller is finally operable to, in response to determining that the pressure difference is greater than the frost threshold or the fouling threshold, determine a blocked condition on the coil.

First claim

The invention claimed is:

1. A controller for a heating, ventilating, and cooling (HVAC) system, comprising:
an interface configured to receive feedback data from a fan of the HVAC system;
a memory operable to store a fan model and a plurality of thresholds; and
a processor communicatively coupled to the memory and the interface, the processor operable to:
determine a virtual sensor measurement based at least in part upon the feedback data from the fan and the fan model, the virtual sensor measurement indicating the static pressure across a coil of the HVAC system;
determine that the virtual sensor measurement is greater than at least one of a group consisting of a frost threshold and a fouling threshold;
in response to determining that the virtual sensor measurement is greater than at least one of a group consisting of the frost threshold and the fouling threshold, determine a blocked condition on the coil;
determine that the virtual sensor measurement is greater than the frost threshold;
determine that an outdoor temperature is less than a freezing threshold;
determine that the HVAC system is running a heating mode;
in response to determining that the virtual sensor measurement is greater than the frost threshold and that the outdoor temperature is less than the freezing threshold and that the HVAC system is running in a heating mode, determine that the blocked condition on the coil is a frosted coil; and

in response to determining that the blocked condition on the coil is the frosted coil, instruct the HVAC system to initiate a defrost cycle.

2. The controller of claim 1 , the processor further operable to:
determine that the virtual sensor measurement is greater than the fouling threshold;
in response to determining that the virtual sensor measurement is greater than the fouling threshold, determine that the blocked condition on the coil is a fouled coil; and
generate an alert that the coil is fouled.

3. The controller of claim 1 , the processor further operable to:
determine that the virtual sensor measurement is greater than the frost threshold at a first time;
in response to determining that the virtual sensor measurement is greater than the frost threshold, initiate a defrost cycle at a second time;
determine that the virtual sensor measurement is equal to or less than a no-frost threshold at a third time, the third time being after the first time and the second time; and
in response to determining that the virtual sensor measurement is equal to or less than a no-frost threshold at the third time, end the defrost cycle.

4. The controller of claim 1 , the processor further operable to:
determine that the virtual sensor measurement is greater than the frost threshold at a first time;
in response to determining that the virtual sensor measurement is greater than the frost threshold, initiate a defrost cycle at a second time;
determine that the virtual sensor measurement is within a range of a no-frost threshold at a third time, the third time being after the first time and the second time;
in response to determining that the virtual sensor measurement is equal to or less than a no-frost threshold at the third time, end the defrost cycle; and
update the no-frost threshold based on the virtual sensor measurement at the third time.

5. The controller of claim 1 , wherein the processor is further operable to, in response to determining a blocked condition on the coil, generate an alert indicating that there is a blocked condition on the coil.

6. The controller of claim 1 , wherein the frost threshold and the fouling threshold depend at least in part upon the speed of the fan.

7. A heating, ventilation, and air-conditioning (HVAC) system, comprising:
an outdoor unit, the outdoor unit comprising a fan and a coil; and
a controller communicatively coupled to the fan and the coil, the controller operable to:
receive feedback data from the fan of the HVAC system;
store a fan model and a plurality of thresholds;
determine a virtual sensor measurement based at least in part upon the feedback data from the fan and the fan model, the virtual sensor measurement indicating the static pressure across the coil;
determine that the virtual sensor measurement is greater than at least one of a group consisting of a frost threshold and a fouling threshold;
in response to determining that the virtual sensor measurement is greater than at least one of a group consisting of the frost threshold and the fouling threshold, determine a blocked condition on the coil;
determine that the virtual sensor measurement is greater than the frost threshold;
determine that an outdoor temperature is less than a freezing threshold;
determine that the HVAC system is running a heating mode;
in response to determining that the virtual sensor measurement is greater than the frost threshold and that the outdoor temperature is less than the freezing threshold and that the HVAC system is running in a heating mode, determine that the blocked condition on the coil is a frosted coil; and
in response to determining that the blocked condition on the coil is the frosted coil, instruct the HVAC system to initiate a defrost cycle.

8. The system of claim 7 , the controller further operable to:
determine that the virtual sensor measurement is greater than the fouling threshold;
in response to determining that the virtual sensor measurement is greater than the fouling threshold, determine that the blocked condition on the coil is a fouled coil; and
generate an alert that the coil is fouled.

9. The system of claim 7 , the controller further operable to:
determine that the virtual sensor measurement is greater than the frost threshold at a first time;
in response to determining that the virtual sensor measurement is greater than the frost threshold, initiate a defrost cycle at a second time;
determine that the virtual sensor measurement is equal to or less than a no-frost threshold at a third time, the third time being after the first time and the second time; and
in response to determining that the virtual sensor measurement is equal to or less than a no-frost threshold at the third time, end the defrost cycle.

10. The system of claim 7 , the controller further operable to:
determine that the virtual sensor measurement is greater than the frost threshold at a first time;
in response to determining that the virtual sensor measurement is greater than the frost threshold, initiate a defrost cycle at a second time;
determine that the virtual sensor measurement is within a range of a no-frost threshold at a third time, the third time being after the first time and the second time;
in response to determining that the virtual sensor measurement is equal to or less than a no-frost threshold at the third time, end the defrost cycle; and
update the no-frost threshold based on the virtual sensor measurement at the third time.

11. The system of claim 7 , wherein the controller is further operable to, in response to determining a blocked condition on the coil, generate an alert indicating that there is a blocked condition on the coil.

12. The system of claim 7 , wherein the frost threshold and the fouling threshold depend at least in part upon the speed of the fan.

13. A non-transitory computer readable storage medium comprising instructions, the instructions, when executed by a processor, executable to:
receive feedback data from the fan of the HVAC system;
store a fan model and a plurality of thresholds;
determine a virtual sensor measurement based at least in part upon the feedback data from the fan and the fan model, the virtual sensor measurement

Assignees

• Lennox Ind Llc
• Lennox Ind Inc

Inventors

• Gokhale Umesh
• Berg Eric
• Douglas jon

Classifications

• F24F11/42

  of outdoor units · CPC title

• F24F2110/30

  Velocity · CPC title

• F25B2500/04

  Clogging · CPC title

• F24F11/62

  characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values · CPC title

• F24F11/41 Primary

  Defrosting; Preventing freezing · CPC title