Greenhouse Automation - Thermal Controller

The thermal controller is currently in the final stages of testing prior to construction of the prototype. As indicated in the System Architecture section, the thermal controller will perform the dual function of gathering temperature data from the growing area as well as providing control of valves or other water circulation devices. Up to twenty temperature sensors can be connected to the controller and located at appropriate positions in the growing area, including locations within the soil. The sensors employ the DS18B20 digital thermometer encased in a stainless steel waterproof housing shown below.

These sensors are readily available on Ebay at an affordable price and are easily wired in a parallel configuration to the controller.

The thermal controller also provides seven on/off 35V AC RMS / 50V DC 0.5A solid-state switch outputs for general control of low voltage greenhouse devices. Power for the devices may be drawn from the 12 VDC supply available at the controller or may be drawn from another external power source. In the prototype system, these outputs are planned for actuating water valves or, using relays,  motors or heating units. The valves and other water circulation devices will be used for automated irrigation and to perform operations associated with a thermal storage strategy. The heating units will provide an auxiliary source of heat when the solar storage is insufficient for maintaining the minimum greenhouse temperature.

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This page last revised on 08/18/2017