Humidity control for air conditioning system

• US 8,091,375 B2
• Filed: 05/10/2006
• Issued: 01/10/2012
• Est. Priority Date: 05/10/2006
• Status: Active Grant

• Current Assignee: Trane International Inc. (Trane Technologies plc)
• Original Assignee: Trane International Inc. (Trane Technologies plc)
• Inventors: Crawford, Roy R.
• Primary Examiner(s): Swann, Judy
• Assistant Examiner(s): COX, ALEXIS K
• Application Number:
  US11/431,728
• Publication Number:
  US 20070261422A1
• Time in Patent Office: 2,071 Days
• Field of Search: 621/761, 621/58, 621/57, 621/78, 621/80, 236/44.A, 236/44.C
• US Class Current: 62/161
• CPC Class Codes: F24F 11/0008 for air-humidification F24F11/30 takes precedence
• 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 11/65 for selecting an operating mode
• CPC Class Codes: F24F 11/74 for controlling air flow rate or air velocity
• CPC Class Codes: F24F 2110/20 Humidity
• CPC Class Codes: G05D 22/02 characterised by the use of electric means

Abstract

In an air conditioning system for circulating cooled air to an enclosed space, a controller including a temperature sensor, a humidity sensor and a microcontroller for controlling the indoor fan or blower to prevent operation of same if a fan run-on mode is selected or continuous fan operation is selected and the humidity sensed in the enclosed space is greater than a predetermined amount. Continuous fan operation is allowed unless the humidity exceeds a user defined setpoint during an air cooling operating mode. If the humidity sensed is greater than the predetermined amount, the fan is operated only when the system is providing cooled air, such as when the system compressor is energized.

Claims

1. A method of controlling an HVAC system, comprising:

allowing a user of a thermostat controller of the HVAC system to select between enabling and disabling a humidity control for use in a cooling mode of the HVAC system that selectively operates a compressor in response to a call for cooling, wherein the disabling the humidity control comprises allowing the user to override an otherwise automatic enablement of the humidity control;

Enabling the humidity control in response to the user selecting to enable the humidity control via the thermostat controller;

operating a fan of the HVAC system according to an overridable user selectable fan control preference that, when not overridden by the humidity control, causes operation of the fan independent of a call for cooling of the HVAC system; and

in response to enabling the humidity control, operating the humidity control to selectively override the overridable user selectable fan control preference that, but for being selectively overridden by the humidity control, causes operation of the fan independent of the call for cooling;

wherein operating the humidity control comprises after selectively overriding the overridable user selectable fan control preference, discontinuing the overriding of the overridable user selectable fan control preference; and

wherein the discontinuing the overriding of the overridable user selectable fan control preference is conditioned on a comparison between a humidity setpoint selected via the thermostat controller and a sensed humidity.

2. The method of claim 1, further comprising:

operating the thermostat controller to advise the user that the user prefers the overridable user selectable fan control preference, but the fan is not operating because of a high relative humidity.

3. The method of claim 1, wherein the overridable user selectable fan control preference, when selected by a user, is an indication that a user prefers to continuously run the fan during periods of time that the compressor is not operating.

4. The method of claim 1, further comprising:

operating the HVAC system in response to a call for cooling while the humidity control is enabled;

operating the humidity control to compare a humidity setpoint to a sensed humidity; and

after operating the HVAC system in response to the call for cooling while the humidity control is enabled and in response to the comparison of the humidity setpoint to the sensed humidity, at least one of overriding the operation of the fan according to the overridable user selectable fan control preference and resuming operation of the fan according to the overridable user selectable fan control preference.

5. The method of claim 4, further comprising:

during the at least one of overriding and resuming operation of the fan according to the overridable user selectable fan control preference in response to the comparison between the humidity setpoint and the sensed humidity, operating the thermostat controller to select operation of the HVAC system with the humidity control disabled;

wherein the operating the thermostat controller to select operation of the HVAC system with the humidity control disabled discontinues controlling operation of the fan in response to the comparison between the humidity setpoint and the sensed humidity.