Differential Thermostat (Discontinued)
The ETD is an electronic difference thermostat e.g. for ON/OFF control of the temperature difference between the heating source and storage tank in solar heating units and other types of heat recovery plants. The thermostat is constructed for ON/OFF control of the difference between two temperatures. The built-in relay is activated as soon as the sensor temperature in the heating source exceeds the temperature in the storage tank with the °C which has been set with the "START DIFF". The real start difference is the same as the setting of "START DIFF" + "STOP DIFF". At the same time the red light diode is on on the front of the thermostat. The relay will be activated until the temperature difference has fallen with the °C which have been set with „STOP DIFF“. Then the relay releases and the LED goes out. By means of a switch on the front a pump can be guided to constant operation. (Switch in position ON). This function can be used for starting of unit as control of pump. This function may also be used if the solar heating unit has to be secured against boiling over, if there is no need for heating during a longer period of time.