Abstract: An environmental control system for controlling heating, ventilation, humidification and air conditioning equipment located in plant area of a house includes a kit consisting of a remote control unit located in a living space of a house that is linked by a four wire link to a main control unit located in or adjacent the plant area. The remote control unit has a temperature control device, a humidity control device, and a fan control device. Additionally, the remote control unit may include indicating devices and/or an internal battery charger for a rechargeable battery that may be used to operate electronic circuits and controls in the remote unit. AC power from an AC transformer in the plant area is supplied to each of the control devices via the four wire link. The main control unit has relay coils coupled to the four wires in the wire link via selectively poled diodes.

Abstract: A system for HVAC and humidification includes a control signal source which supplies two distinct control signals over two wires of a four wire link. The control signals are supplied to a temperature control signal source and for a fan/humidity control signal source. The temperature control signal source generates a temperature control signal and transmits the temperature control signal to a temperature signal decoder by means of a third wire of the four wire link. The temperature signal decoder decodes the temperature control signal and turns on either a furnace or an air-conditioner. The furnace and the air-conditioner each have a connection to a fan so that the furnace and the air-conditioner can each signal the fan to blow the heated or cooled air into the living area. The fan/humidity control source operates independently of the temperature control signal source and generates a fan/humidity control signal for transmission over a fourth wire of the four wire link.