Another suprising source of noise and error is at the thermocouple connections. This can introduce an error voltage equiv. of almost 10 degrees under some conditions. I correct this by connecting a second thermocouple in revers and series at the connector block. This will cancle most of the thermo-noise and correct the error created by the 3 thermocouples (your actual one pluss the 2 created at the terminal blocks). This is a non-issue in some applications however when an error of a fiew degrees results in time change of 30 minutes this becomes parimoun! I have to search for the data sheets that better explain this, but if you are interested I can file attach the PDF to your email.