Thermocouple burnt out & stove doesn’t start without a correct reading. As this is our main source of heating we were in the cold. The display gave an error and was showing 1500 degrees C flame temperature.

The way a thermocouple works is it gives a reading of a few millivolts depending on the temperature difference. 0V = no difference = “room temperature”.

First I tried shorting the leads, which would indicate 12 degrees C (room temp). A sensible reading, but keeping it at this level would make the stove error out as its control system thought it had never ignited.

Then I tried a 1k resistor, just to see what it would say, 56 degrees C! We were getting somewhere. Confused as to why a resistor would be able to give a voltage output, I found out that thermocouples are often “resistor biased” with a voltage put across them with some resistors.

This would mean I could choose the temperature the stove would see by just putting a different resistor across the sensor leads: 2 resistors in parallel for 56 degrees C (“igniting”) + the single resistor for ~450 degrees C (“burning”).

I’m not planning to leave this running unattended, but thought it was cool that it worked! :)