Method for determining the switching-off criterion of a gas-heated device and circuit for implementing the method

摘要

Method for determining the switching-off criterion of a gas-heated device with atmospheric burner and flow safety device, use being made of two temperature sensors assigned to the waste gas discharge device and the room opening of the flow safety device, the signals of which act on an actuator of the burner via an evaluating circuit. A decisive criterion for switching off is a temperature difference which is determined depending upon the constructional properties of the device to be monitored and which is varied according to the parameters of device load and device working temperature. According to a circuit for implementing the method, the two temperature sensors are connected to a summer via an adapting stage, an inverter being provided in the branch of one of the two sensors and the output of the summer forming the input of a comparator, the other input of which is acted upon by a reference voltage and the output of the comparator being connected via a timer to an actuator of the heat source.