OK, a lot of information to cover....I hope I can cover it all for you. If something is missing, feel free to keep asking.
First things first - you keep mentioning a thermocouple. Do you really have a thermocouple, or are you using the Maverick ET-73 probes? The ET-73 probes are actually thermistors, not thermocouples. My original controller used thermocouples, the second version switched to the simpler, cheaper ET-73 probes.
I'm going to assume you have the ET-73 thermistors, and I will explain what's going on in the code and where things come from.
All thermistors have a known resistance at any given temperature. That data is generally published in a data sheet (I have attached the one for the ET-73 that I got from their customer service department) It is also possible to model a thermistor using an equation called the Steinhard-Hart equation. It has a few constants (A, B, C) that can be calculated by using the data sheet. I calcluated A, B, and C from the data sheet and applied them to the equation (for more info see
http://en.wikipedia.org/wiki/T...inhart-Hart_equation and
http://en.wikipedia.org/wiki/Steinhart-Hart_equation)
The 22200 is the value of the resistor that is used in conjunction with the thermistor in the voltage divider circuit in my schematic. I had a 22KOhm resistor that I measured to be 22000 ohms. Using the 5V source, the 22200 ohm resistor will take up a percentage of the voltage and the thermistor will take up the other percentage. The thermistor's percentage depends on the temperature.
You are correct - the 1024 is used to convert from the A/D converter reading to a fraction. The 273.25 is used to convert from degrees Kelvin (which the Steinhart-Hart equation uses) to degrees C. Then it is converted to degrees F.
Making any sense now? Hope I am helping more than adding confusion.