I have a 4-5 year old Quickmill Alexia (the one that you have to take off the back to adjust pressure) with a Watlow SD PID. How can I tell what my offset is? When I run through the PID using the green circle I come across -24 CAL is that my offset? So at 224 degrees my actual temp is 200?

I don't have that machine but I will take a shot. That does sound like it is the offset. On an E61 machine the boiler temperature must be set 20-35 degrees higher than the temperature that you want to come out at the group head. The offset is there to help translate this difference to the user but it does not impact the function of the machine - it only changes the number displayed.

Do you know what brand PID is installed?

My PIDS do not have offsets (5 PIDS on 3 machines) and I have just adjusted the temperature settings by taste. Too bitter go lower 1-2 degrees, too sour go higher 1-2 degrees, and keep trying until you are satisfied. If you can't tell the difference then you can say "I guess it is okay" or you can keep going up or down until you can tell that it changed. This taste testing works best when you make the shot, stir it up with a spoon, and taste test half a spoonful (I need to blow on it before tasting) right after making the shot. If you taste at different amounts of time after the shots or taste in milk it is harder to tell the difference that the temperature change makes.

You can then set the offset to whatever you want. You could set the offset so the display says 200 for the temperature you use for your favorite coffee so that is the reference point you use when making adjustments for other cofees.

So I looked on the PID PDF and it said that CAL means Calibration Offset is that the offset? I know my question sounds stupid but I have no idea about electric stuff or PIDs. Im just annoyed because certain espresso require certain temps and I want to know what my temp is!

Looking at the manual:
http://www.watlow.com/-/media/documents ... 31-06.ashx

CAL is described as an offset to the input reading. It would be used to adjust for a temperature sensor that gave a consistent but incorrect reading. From the manual:

• Calibration offset allows a device to compensate for an inaccurate sensor, lead resistance or other factors that af- fect the input value. A positive offset increases the input value, and a negative offset decreases the input value.
  The input offset value can be viewed or changed with Calibration Offset ['CAL] (Operations parameters).

I didn't see any place for any other offset.

So this manual makes it seem like I put the temp between 195-205 not take into consideration the offset and set it at 224 since it reads -24 CAL on one of the screens when scrolling through...The PID in the picture is what I have.

After poking around a bit it appears that the common practice using this PID unit for espresso machines is to use the offer as you described. The temperature difference for most E61 machines is around 25 degrees so the -24 value should work reasonably well.

If you have the opportunity to install a thermometer in the group you may find that your offset is slightly different. If so, change the offset.

The reason for variation between different machines (even of the same design) is that during a shot the water comes from both the top and the bottom of the boiler through the two tubes of the thermosyphon. This means that a little bit of difference in the flow rate of the top or bottom tube will result in a different temperature water feeding the group. It also means that your offset might change a little if any scale builds up.

Since you seem to be very interested in knowing the temperature I recommend you install a group head thermometer.
https://www.chriscoffee.com/E61-Group-D ... sss-04.htm

Note that when PIDs are used for process control the offset is used to adjust for sensor error. In this case, the offset is used to adjust for the difference in temperature between the boiler and the group head. This is an example of the general capabilities of the PID are used to meet a wide range of applications. Looking at the Watlow PID manual will show that there are many such configurable capabilities. Each one has a specific behavior that may be used to adapt the PID to the system it's trying to control.