Context adaptive cool-to-dry feature for HVAC controller

• US 9,696,735 B2
• Filed: 04/26/2013
• Issued: 07/04/2017
• Est. Priority Date: 04/26/2013
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Matsuoka, Yoky, Fisher, Evan J.
• Primary Examiner(s): Tran, Len
• Assistant Examiner(s): COX, ALEXIS K
• Application Number:
  US13/871,746
• Publication Number:
  US 20140319231A1
• Time in Patent Office: 1,530 Days
• CPC Class Codes: F24F 3/1405 in which the humidity of the air is exclusively affected by contact with the evaporator of a closed-circuit cooling system or heat pump circuit
• CPC Class Codes: G05D 22/02 characterised by the use of electric means
• CPC Class Codes: G05D 23/1902 characterised by the use of a variable reference value
• CPC Class Codes: G05D 27/02 characterised by the use of electric means

Abstract

A thermostat and a method include using occupancy sensors, temperature sensors, and humidity sensors to control activation of a cooling function of an HVAC system to dehumidify an enclosure. During times when the enclosure is occupied, the cooling function is activated when the humidity exceeds a first threshold humidity, and continues until the humidity drops below a second threshold humidity or the temperature drops below a first threshold temperature. During times when the enclosure is unoccupied, the cooling function is activated when the humidity exceeds a third threshold humidity, and continues until the humidity drops below a fourth threshold humidity or the temperature drops below a second threshold temperature.

Claims

1. A thermostat, comprising:

a housing;

a user interface;

one or more temperature sensors, each of the one or more temperature sensors being configured to provide temperature sensor measurements;

a humidity sensor configured to provide humidity sensor measurements of humidity inside an enclosure in which the thermostat is installed;

an occupancy sensing system that characterizes an occupancy status of the enclosure in which the thermostat is installed from among a plurality of possible occupancy statuses including an occupied state and an away state; and

a processing system disposed within the housing, the processing system being configured to be in operative communication with the one or more temperature sensors to receive the temperature sensor measurements, in operative communication with one or more input devices including said user interface for determining a setpoint temperature, and in still further operative communication with a heating, ventilation, and air conditioning (HVAC) system to control the HVAC system based at least in part on the setpoint temperature and the temperature sensor measurements;

wherein said processing system is further configured to operate in conjunction with said occupancy sensing system to;

during a first time interval during which the occupancy sensing system characterizes the occupancy status of the enclosure as being in the occupied state;

determine that the humidity sensor measurements exceed a first threshold humidity; and

activate, in response to determining that the humidity sensor measurements exceed the first threshold humidity, a cooling function of the HVAC system to reduce the humidity level in the enclosure until any of a first set of conditions has been met, wherein the first set of conditions comprises;

(i) the humidity sensor measurements being less than a second threshold humidity;

(ii) the temperature sensor measurements indicating that a temperature in the enclosure is lower than a first threshold temperature; and

(iii) a first maximum time interval for the cooling function to be active to reduce the humidity level in the enclosure while the humidity sensor measurements change by less than a first predetermined threshold amount; and

during a second time interval during which the occupancy sensing system characterizes the occupancy status of the enclosure as being in the away state;

determine that the humidity sensor measurements exceed a third threshold humidity; and

activate, in response to determining that the humidity sensor measurements exceed the third threshold humidity, the cooling function of the HVAC system to reduce the humidity level in the enclosure until any of a second set of conditions has been met, wherein the second set of conditions comprises;

i) the humidity sensor measurements being less than a fourth threshold humidity;

ii) the temperature sensor measurements indicating that the temperature in the enclosure is lower than a second threshold temperature; and

iii) a second maximum time interval for the cooling function to be active to reduce the humidity level in the enclosure while the humidity sensor measurements change by less than a second predetermined threshold amount.

2. The thermostat of claim 1 wherein the processing system is further configured to wait for a first backoff interval after any of the first set of conditions or any of the second set of conditions are met before again activating the cooling function of the HVAC system to reduce the humidity level in the enclosure.

3. The thermostat of claim 2 wherein the processing system is further configured to:

determine when a threshold number of dehumidification cycles to reduce the humidity level in the enclosure have occurred; and

wait for a second backoff interval after the other of the first set of conditions or the second set of conditions are met before again activating the cooling function of the HVAC system in order to reduce the humidity level in the enclosure.

4. The thermostat of claim 3 wherein the second time interval is at least twice as long as the first time interval.

5. The thermostat of claim 1 further comprising a wire insertion sensing system that automatically detects when a dehumidifier is connected to the thermostat, wherein the processing system is configured to stop activating the cooling function of the HVAC to reduce humidity in the enclosure when the dehumidifier is detected.

11. The thermostat of claim 1, wherein the first humidity threshold is higher than the third humidity threshold, and the first temperature threshold is higher than the second temperature threshold.

12. The thermostat of claim 1, wherein the maximum time interval for the cooling function to be active to reduce the humidity level in the enclosure while the humidity sensor measurements change by less than a threshold amount is 15 minutes.

13. The thermostat of claim 2, wherein the thermostat is configured to wait for the first backoff interval when any of the following conditions are met

(i) the temperature sensor measurements indicate that the temperature in the enclosure is lower the second threshold temperature;

and

(ii) the first maximum time interval or the second maximum time interval for the cooling function to be active to reduce the humidity level in the enclosure while the humidity sensor measurements change by less than the threshold amount has been exceeded.

14. The thermostat of claim 3, wherein the threshold number of dehumidification cycles to reduce the humidity level in the enclosure comprises 3 dehumidification cycles.

6. A method of dehumidifying an enclosure using a cooling function of an HVAC system, the method comprising:

characterizing, using an occupancy sensing system of a thermostat, an occupancy status of the enclosure, the occupancy status being selected from among a plurality of possible occupancy statuses including an occupied state and an away state;

processing humidity sensor measurements of humidity inside the enclosure provided by a humidity sensor of the thermostat, wherein the thermostat comprises;

a housing;

a user interface;

one or more temperature sensors, each of the one or more temperature sensors being configured to provide temperature sensor measurements;

the humidity sensor;

The occupancy sensing system; and

A processing system disposed within the housing, the processing system being configured to be in operative communication with the one or more temperature sensors to receive the temperature sensor measurements, in operative communication with one or more input devices including said user interface for determining a setpoint temperature, and in still further operative communication with a heating, ventilation, and air conditioning (HVAC) system to control the HVAC system based at least in part on the setpoint temperature and the temperature sensor measurements; and

during a first time interval during which the occupancy sensing system characterizes the occupancy status of the enclosure as being in the occupied state;

determining that the humidity sensor measurements exceed a first threshold humidity; and

activating, in response to determining that the humidity sensor measurements exceed the first threshold humidity, a cooling function of the HVAC system to reduce the humidity level in the enclosure until any of a first set of conditions has been met wherein the first set of conditions comprises;

(i) the humidity sensor measurements being less than a second threshold humidity;

(ii) the temperature sensor measurements indicating that a temperature in the enclosure is lower than a first threshold temperature; and

(iii) a first maximum time interval for the cooling function to be active to reduce the humidity level in the enclosure while the humidity sensor measurements change by less than a first predetermined threshold amount; and

during a second time interval during which the occupancy sensing system characterizes the occupancy status of the enclosure as being in the away state;

determining that the humidity sensor measurements exceed a third threshold humidity; and

activating, in response to determining that the humidity sensor measurements exceed the third threshold humidity, the cooling function of the HVAC system to reduce the humidity level in the enclosure until any of a second set of conditions are met, wherein the second set of conditions comprises;

i) the humidity sensor measurements being less than a fourth threshold humidity;

ii) the temperature sensor measurements indicating that the temperature in the enclosure is lower than a second threshold temperature; and

iii) a second maximum time interval for the cooling function to be active to reduce the humidity level in the enclosure while the humidity sensor measurements change by less than a second predetermined threshold amount.

7. The method of claim 6 further comprising waiting for a first backoff interval after any of the first set of conditions or any of the second set of conditions has been met before again activating the cooling function of the HVAC system to reduce the humidity level in the enclosure.

8. The method of claim 7 further comprising:

determining when a threshold number of dehumidification cycles to reduce the humidity level in the enclosure have occurred; and

waiting for a second backoff interval after the first/second set of conditions are met before again activating the cooling function of the HVAC system in order to reduce the humidity level in the enclosure.

9. The method of claim 8 wherein the second time interval is at least twice as long as the first time interval.

10. The method of claim 6 further comprising determining whether a dehumidifier is connected to the thermostat using a wire insertion sensing system, wherein the processing system is configured to stop activating the cooling function of the HVAC to reduce humidity in the enclosure when the dehumidifier is detected.

15. The method of claim 6, wherein the first humidity threshold is higher than the third humidity threshold, and the first temperature threshold is higher than the second temperature threshold.

16. The method of claim 6, wherein the first maximum time interval or the second maximum time interval for the cooling function to be active to reduce the humidity level in the enclosure while the humidity sensor measurements change by less than a threshold amount is 15 minutes.

17. The method of claim 7, wherein the thermostat is configured to wait for the first backoff interval when any of the following conditions are met:

(i) the temperature sensor measurements indicate that the temperature in the enclosure is lower the second threshold temperature; and

(ii) the first maximum time interval or the second maximum time interval for the cooling function to be active to reduce the humidity level in the enclosure while the humidity sensor measurements change by less than the threshold amount has been exceeded.

18. The method of claim 8, wherein the threshold number of dehumidification cycles to reduce the humidity level in the enclosure comprises 3 dehumidification cycles.