The traditional thermostats have been used for decades to control the on/off cycle of the compressor, ensuring that the temperature of the GDM is maintained at the pre-set value at all times. The electromechanical thermostat, Danfoss 077B series, has proven to be a simple and low-cost solution that allows the most basic functionality, i.e. control of the compressor, but with fewer options for achieving energy savings and other benefits that modern, electronic thermostats and controllers can provide.
This thermostat, while cost effective and reliable, typically controls only the operation of the compressor and the potential energy savings offered by combined control of compressor, evaporator fan, and defrost heater cannot be fully realized. To address these issues, an electronic thermostat can be installed in place of the traditional electromechanical thermostat.
First of all, the electronic thermostat, offered by Danfoss as ETC 1H range of controllers, lowers the energy consumption by optimizing the operation of fan, defrost heater and condenser (optional) along with compressor. The electronic thermostat also offers high accuracy of temperature control due to close differential and narrow tolerances which remain stable over time. Sensors to control the cabinet temperature, the evaporator defrost and the condenser temperature may be added to enhance performance. Furthermore, the electronic thermostat typically has a built-in timer for defrost and other functionalities like initial pull-down and alarm delay. In addition to providing energy savings, the ETC 1H range of electronic thermostats provides voltage protection and zero cross-over relay technology that increases the life of the controller.
Electronic thermostats are similar in shape and size to conventional thermostats making them easy to apply in existing designs. To fulfill the wish for an external display of temperature on the GDM - a wish that has become more or less standard today - the electronic thermostat may be connected to an external display; a feasible solution, but requiring extra work on the assembly lines.