Adam and Ioanis, both of the solutions will works if i combine them. Optocoupler in series with heater is not feasible due to the amount of heat dissipation on the limiting resistor for the diode on the optocoupler. Also , as current varies from 0 to 5 amps, will be difficult to get a resistor value to light the led in the opto at everything over one amp, but do not fry the LED at 5 amps. Like Adam suggested, i will try to use the output from the ACS712. Here, i am going back to Ioannis advice to use an integrator to get a proper DC voltage out of the sine wave. From the DC voltage i need to use a comparator to get an output fro any voltage over 2.6 volts.
Ioannis, do you have any schematic for an integrator which will works on the voltage diagram posted above.
Let's say the Amps going through the heater are 5 A, so i will have a sine wave going up and down between +2vdc to +3vdc, where the 2.5 volts is the zero crossing point for zero amps. I need some kind of schematic to convert that sine wave to a dc line at 3 volts
Best regards
Ion