System is running well with the third batch dehydrating.

An issue has been identified with the location of the max6675.  As it is located within the head of the oven it is exposed to temperature increases as the main oven is heated.

I believe that the cold junction compensation is unable to deal with these changes and begins to return readings that are less than the actual temperature.

Ideally the max6675 needs to be thermally isolated from the thermocouple.

Initially the error is about 20deg an over time settles down to about an 8 deg error.

Due to the high temperatures, the only real option is a thermocouple but suffers from the issue above.  All other cheap temperature sensors are limited to about a max of 150 deg C, understandable as they are often semiconductor based.

To deal with this issue I added a Cal slider so I can add the required offset.  Which is usually set to 8.