Question

How many millivolts should a thermocouple read?

Answer 1

The normal millivolt output is 25 to 35 millivolts but on some thermocouples, you may even get a millivolt reading of up to 35 which is normal.

The pilot flame that is heating the thermocouple should be adjusted so that it's a soft blue flame and not roaring or lifting.

Answer 2

A millivolt reading on a good thermocouple should read between 25 and 35 volts which means the reading is normal the thermocouple is okay.

Sometimes though a thermocouple could become dirty at the tip which could cause the termocouple to not working properly and not detect the heat which can shut off the pilot in the furnace or other gas appliance that uses a thermocouple.