I have a problem: I have a gas heater at home. It is used for heating home and water by TERMET. And the problem is that I get an E2 error and I don't know what it is. I have three knobs on it to adjust the temperature, two knobs to change the mode and check the water pressure. And the stove runs for a while, an error pops up, I check the pressure with the knob and it starts working normally again and it works like that for 20 minutes and the error comes up again. Does anyone have any idea what this error is about, what is causing it???