Max error without reference junction

[Hammer]

Hi I'm using thermocuple as a temp. sensor, it is inside soldering handle output is 0 mV (tested with digital voltmeter at range 200 mV) at room temperature.
I'll amplify that voltage using AD623

I cannot use Ice bath to set ref. junction at 0 deg C. I thought using table (ref junction at 0 deg C) and formula to calculate temperature.

My question is what max error without using any compensation will I have.

Will it be actual temp of soldering hand + room temp or will it be low error like +-1 deg C which will suit me (I don't need it to be so precise)?

I will regulate temp automaticly from 160 deg C to 460 deg C

 

[dlgoff]

Your thermocouples output is proportional to temperature change. So put you TC in a know temperatrue source (say boiling water) and note the mV reading. Then put it in another know temperature source (say ice water) and note this mV reading. Now you have your scale.