While most furnaces and boilers have a thermocouple, in some boilers and gravity furnaces a thermopile (pilot generator) will generate electricity to operate the gas control valve.

For temperature measurement, [Andy] was using a type-k thermocouple and a Maxim MAX31855 thermocouple to digital converter.

When air is present it dissipates the heat, when under vacuum the heat builds and causes the thermocouple to generate some voltage on its connections.

A Rolled Organic Thermoelectric Generator with High Thermocouple Density Journal: Advanced Functional Materials Published: 2024-07-01 DOI: 10.1002/adfm.202400982 Affiliations: 3 Authors: 10 Go to ...