Replacing my Kiln's Thermocouple 

FYI I fired my kiln on this thermocouple, both bisque and glaze firings and it was all good!

Hi Kent, I'm so glad you shared this. I was thinking about replacing mine for a first time and was postponing since I do not feel very confident on doing it. So this is gonna be very useful! I bought a very old model of Italian kiln a year ago and I've got and extra thermocouple for replacement. Fingers crossed that all will work after my replacement :)

7:30 Thermocouple works by generating voltage that is proportional to the difference temperature between hot and cold junction of a thermocouple. The tip of a thermocouple where two different materials meet is called a "hot junction" and the point where thermocouple wires end is a "reference junction" or "cold junction". Difference of the temperature generates voltage across thermocouple wires and that voltage after amplification indicates the temperature in your kiln. Important thing to remember is that thermocouples don't measure absolute values, only the difference. For example, let's say your kiln is at 1200°C and your thermocouple is connected by normal copper wire from its terminal block to your controller. In that case your reference junction is at the other end of a thermocouple and it is sitting at around 50°C (arbitrary number I don't know real values) so the thermocouple will generate voltage indicating a temperature of 1200-50=1150°C. Kiln controllers use some type of a "cold junction compensation" so it knows what temperature the "cold junction" sits at and adds that to the equation to indicate the correct temperature at the tip of the thermocouple. In your case I assume you have your thermocouple connected with a special type of compensation wire and it goes straight to your kiln controller, so there is your "cold junction". Connecting a thermocouple with a compensation wire (a special type of wire made from the same material as a thermocouple that is not creating any junction that can affect your measurement) allows you to place your "cold junction" whenever you want, for example a couple of feet away from your kiln in a room temperature.