Humidity control algorithm

Abstract

A system and method is provided to control the operation of an HVAC system to remove humidity from an indoor air environment without cooling the indoor air environment. The system includes a thermostat that operates the HVAC system to remove humidity when the sensed humidity falls below a humidity set point. After operation of the HVAC system, the thermostat monitors whether the temperature within the indoor air environment falls due to the operation of the HVAC system. If the temperature within the indoor air environment falls consistently, the humidity control algorithm determines that the HVAC system cannot operate without cooling and prevents future operation of the HVAC system to provide only dehumidification. If, however, the humidity control algorithm determines that the HVAC system can operate to dehumidify without cooling, the humidity control algorithm operates the HVAC system accordingly.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]The present application is based on and claims priority from U.S. Provisional Patent Application Ser. No. 60 / 797,633 filed on May 4, 2006.BACKGROUND OF THE INVENTION[0002]Recently, there have been many advancements in the operation of HVAC systems regarding humidity control. In particular, there currently exist HVAC systems that are capable of removing humidity from the air without cooling the air. In many of these systems, humidity is removed from the air and, once the humidity has been removed, the dehumidified air is heated enough such that the air returned to the enclosed environment has not been cooled.[0003]As with many technological advances, the controls and control algorithms for HVAC systems have lagged the advances in the physical equipment. Presently, thermostats or HVAC controls only call for dehumidification when there is also a call for cooling or when the current temperature of the indoor air environment is close to the coo...

AI Technical Summary

Benefits of technology

[0009]In this manner, the thermostat operates the HVAC system without knowing whether the HVAC system is capable of dehumidifying without cooling. If the thermostat learns that the HVAC system is not capable of dehumidifying without cooling, the thermostat will discontinue activating the HVAC system for dehumidification purposes only in the future. In this manner, the thermostat can learn the operational characteristics of the HVAC system and utilize performance characteristics of the HVAC system to provide for improved cooling and dehumidification functions.

[0010]In one embodiment, the thermostat senses the starting temperature in the location near the thermostat and within a building or room having the indoor air environment controlled by the HVAC system. In this embodiment, both the starting temperature and the current temperature are temperatures measured near the thermostat. In an alternate embodiment, the system includes a temperature probe positioned to sense the temperature of the air flow leaving the HVAC system. In this alternate embodiment, the temperature probe relays the current temperature of the air flow from the HVAC system to the thermostat such that the thermostat can compare the temperature of the air flow leaving the HVAC system to a starting temperature that is related to the temperature of the indoor air environment being controlled by the HVAC system. The use of a temperature probe to sense the air flow from the HVAC system provides a more immediate indication of whether the HVAC system is capable of operation to remove humidity without cooling the indoor air environment.

[0012]Alternatively, the method could be further enhanced by providing a temperature probe at an outlet vent for the HVAC system. By observing the temperature at the outlet vent, rather than at the thermostat or control itself, the thermostat could respond faster to equipment that does cool and prevent undercooling, and thus not leave the homeowner uncomfortable. The thermostat could also, after several cycles, “remember” that the equipment is capable of dehumidification without cooling.

Problems solved by technology

However, currently available thermostats and HVAC controllers are not capable of operating the HVAC system as a dehumidifier independently when the temperature within the building is below the cooling temperature set point such that a demand for cooling is not indicated.

In these situations, the thermostat will not know the operational characteristics of the HVAC system or appreciate the HVAC system's ability to dehumidify the air without additional cooling.

Thus, the thermostat may not utilize the ability of the HVAC system to dehumidify the air within the indoor air environment being controlled.

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