tldr: Heating/Cooling Regulation not working despite troubleshooting.
I am a commercial user, running 900g batches back to back typically for a medium espresso roast that finishes before second crack. I have had some trouble with the Bullet for a few months now.
Here’s the problem. After a few roasts, the thermal mass of the machine gets to be too hot and it becomes unable to regulate its temperature. This usually presents itself after drop by running past the next pre-heat temp and into the 300’s (Celsius). Even after putting the machine into cooling cycle, it will keep overheating until I have to turn it off and then on so it will reset and then cool back down. I know I should not do this, but its the only thing that has worked once it gets in this “mood”.
Once it begins cooling down, it must cool down below 180 degrees, before it will start heating up. It will do the opposite, it will cool and cool and cool, until let it cool to almost room temp, when it feels comfortable heating back up again.
This has been happening with more and more frequency, even after adjusting my recipes and their pre-heat settings to eliminate some of the thermal mass issues. Today, it simply stopped heating about a minute into my first roast.
In that time I have upgraded my setup, added better ventilation, an underbelly fan, and stopped venting the cooling through the legs. I would imagine I need to replace my Induction PCB, but there is no store that sell these. As a R2 owner, Sweet Marias only carries that part for R1 AND R1 V2.