Abstract: An economical energy-saving air-conditioning system for cooling air in an enclosure requiring year-around cooling. An outdoor heat exchanger is operative in a recirculating liquid closed-loop cooling system. A temperature controlled actuator provides continuous free cooling when the outside temperature is approximately 35.degree. to 40.degree. F. or less; and provides free pre-cooling of the air when the outside temperature is in the 35.degree. to 65.degree. F. range. The closed-loop comprises conventional components for summer temperature cooling; and, in less-than summer temperatures the present invention utilizes the outside heat exchanger to provide cool heat exchange liquid to a (free) cooling coil positioned to confront the air stream in advance of a refrigerant coil. Reheat for dehumidification is provided in an embodiment wherein thermal energy is taken from the waste heat of the refrigerant system.

Abstract: Temperature and humidity electrical/electronic control circuits and apparatus to maintain a room at a constant temperature and humidity. The control system is adapted to an environmental condition controller for year-around cooling utilizing a liquid recirculating to an outside coil for free cooling or free reheat dehumidification. The controls provide a sequencing function to actuate one or more temperature and/or humidity conditioners in response to the degree and percentage of change. The circuit provides a ramp function signal for proportional control over an initial temperature range of free cooling and step controls over other predetermined temperature ranges. The circuit comprises a high fidelity ramp generator linearly responsive to the degree of temperature change up to a predetermined set point. A dehumidification signal is developed and fed to the same ramp generator to carry out air cooling to remove moisture.