Abstract: A system for controlling temperature and humidity in an enclosure, that has a central air conditioning system; a dehumidifier attached to a return air duct of the central air conditioning system; and a system control unit that comprises a thermostat, dehumidstat and can control a cooling solenoid valve to provide temperature control, and control a dehumidifier solenoid valve to provide humidity control. The cooling solenoid valve and the dehumidifier solenoid valve can be independently activated based on the temperature and humidity of the enclosure. Embodiments of the present invention include systems that are easily modify existing air conditioning systems.

Abstract: A geothermal heating and/or cooling system includes one or more of a plurality of features that enhance the efficiency of the system. Preferably, the system includes a subterranean heat exchanger having tubes disposed against a conductive sheet. The system also preferably includes a reservoir vessel for holding a supply of heat transfer fluid in a liquid phase. Also, the system preferably includes heat exchange means for exchanging heat between the heat transfer fluid and the outdoor air. In addition, the system preferably has an automatically adjusting cooling expansion valve controlled by a sensor disposed to detect the pressure or temperature of heat transfer fluid exiting an indoor air handler in a cooling mode, the system also preferably has an automatically adjusting heating expansion valve controlled by a sensor that is preferably located so as to detect the temperature or pressure of heat transfer fluid flowing from the subterranean heat exchanger to a gas compressor.