How to test a thermopile?

To test a thermopile, first ensure that the device is disconnected from any power source. Use a multimeter set to measure millivolts; connect the multimeter leads to the thermopile's terminals. Heat the thermopile with a flame or a heat source, and observe the voltage reading on the multimeter; it should produce a voltage in the range specified by the manufacturer. If there is little to no voltage output, the thermopile may be faulty and should be replaced.