Generally used in systems that work with temperatures below 0 ° C (negative temperatures), resistance defrosting is thus called because it performs its function with the aid of electrical resistors, fixed between the evaporator fins, which, when actuated, heat the surfaces of the evaporators. evaporator fins providing the heat needed to melt the accumulated ice.
During this type of defrost the evaporator forcers must be switched off to prevent the heat generated by the resistors from being transmitted to the circulating air and consequently to the stored products, thus causing their temperature to rise. The compressor is also turned off.
In some specific applications, in the chamber control system, a bimetallic thermostat or electronic thermostat is added, in series with the resistor maneuvering device, this thermostat prevents defrosting if the internal temperature of the chamber is high and does not allow Ice formation. A clearer example of the operation of this application is defrosting when the equipment is turned on at an early stage, ie after a long standstill, the internal temperature of the chamber tends to balance with the temperature of the external environment at this temperature. No ice formation occurs and in the event of a defrost at startup we would be heating the evaporator fins in vain, representing a waste of electricity.
