consider this.. (my current set up)
TO fan is on one plug... it stays on constant..
TO heat is on another plug, dial on high.. it is plugged into a relay controlled by the PID
the PID is a thermometer for the most part, I lift the handle on the TO to cut the heat (but not the fan) if I want to slow the progress of the roast and I lift the lid to see the beans and factor that into the roast curve (all mental/zen like roasting)
the PID is usually set around 430 F so it dose start to turn on and off as I get close but at its current settings I can easily find second crack if I want..
separate the heat and fan, keep the heat wired through the TO handle kill switch and try it.. add the variac with plug and and an outlet if it doesn't work.. I like modular then I can move things around between experiments ![Cheesy :D](https://www.greencoffeebuyingclub.com/Smileys/default/cheesy.gif)
Here's the problem I saw as I was logging the data: The CO controls do not manage power, only the set point temp (
ex: if you set the controls to 400°F, the power is on 100% until the tstat reads 400°F - then the element shuts off until the bottom range of the dead bands is reached).
If you're running the CO through the controls, then you're dealing with a thermostat if the tstats preset is reached. And a PID won't change the need to control the power - it's still running the element at 100% to a predetermined set point, then shutting the element off. Granted, it's turning the element on/off in a more controlled manner, but it's also only doing that for one temp. To change the PID set point requires changing the PID parameters, not that simple to do on the fly.
I'm going to wire the element directly to the variac (at house current) and manage the power and fan separately, just like the Hottop. This way I can run the CO at a fixed percentage until I reach a certain temp, then change the percentage until the next temp milestone is reached. It won't be programmable, but it will be very repeatable.
example: 50% power to 350°, then up the power to 75° until 400°, then drop power to 50%, and coast through 1st crack, and when 2nd crack begins run the power to 100%. The same pattern would probably be necessary for the fan.
It's a similar problem we have with PID's in espresso machines. A PID isn't very useful in maintaining intra-shot temps. The PID's strength is achieving predictable and stable starting temp in an espresso machine. Based on what I observed with the TurboCrazy I PID'd, the temp is better managed with power and fan control than by trying to manage temps using a PID's set point.