Deep Clean Affecting Proven Recipes?

I’ve developed some tried and true recipes for myself and friends. After finishing my last roast session I knew it was time for a cleaning. So, I just recently did a VERY deep clean of my roaster and now the weirdest thing is happening to all those dialed in recipes. Almost all of my recipes are now delayed by 1-2min. What I mean by that is most every 775g recipe I would roast would finish about the 11min mark give or take 45s-1m without ever getting into a position to stall out. Ever since that cleaning the roast times have been extended to 13+ min and I’ve had to manually adjust F and P settings toward the end of the roasts to avoid stalls.

What the heck happened?!

Here’s an example of a natural ethiopian light roast I have been roasting for the last 4-5 months.

Can’t comment except to speculate that the cleaning may have increased volumetric air flow via the exhaust fan. That will remove some small additional amount of heat which will then require longer to reach target temps compared to pre-cleaning. My own experience with cleaning hasn’t produced that large an effect but then I use lower fan speeds (F2, F3).


Very deep clean should mean the temperature sensors too, right? If that is so, once the IBTS gets dirty, it will signal a lower than actual temperature, at least from my experience. Hence, the faster roasts. By the way, that was my experience on all temperature probes and sensors. So, from my point of view, it’s perfectly normal. What you can do is maintain the level of clean and recreate the recipe with the correct temperature values. It’s easier this way, as you can react and clean as soon as you see differences. Maintaining the same level of dirty would prove more difficult.

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Just out of curiosity, how deep is VERY deep? You did not touch the drum, did you?

Correct. What you’re saying makes sense , I think, but why would a lower than actual temperature produce a faster roast?

I didn’t touch the drum but I did remove one of the shims between the bearing and drum shaft because I have a bunch of Guji beans that are the tiniest bean I’ve ever seen and keep falling through the chaff chute. What are you thinking?

You know Bruce that was one thing I was thinking as well. One of the things that I cleaned back to original pristine condition was the chaff filter that catches are the fines and dust. I let it soak in Cafiza until there was no oils left on it and thought that it was actually increasing airflow (improving airflow?) even with the same recipe settings

Well, I remember that, in the early days, as part of a deep cleaning, someone cleaned their drum so it was nice and shiny, just like new!

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Oh hahahaha yeah, none of that

Well, if it gives lower than actual, it means that the thing holds true for the preheat, among other things. Higher PH=faster roast, especially when you don’t know it’s higher. And we’re also talking about what would produce a faster roast between the two, not in general. Having higher temperatures than the ones you’re reading will do that.

Ok I understand what you’re saying now and it makes a lot of sense. Right before the cleaning I actually decreased PH temp because roasts were a little too fast for my preference. Now I understand why. I’ll try bumping my PH temp back up 5*C to where they were a few roasts ago. Thanks

I will say this has been super annoying to course correct these recipes after that cleaning. Everything has been *fine but not where I had them before :sob: nothing worse than having a variety of recipes dialed in and consistent to now having to workshop them all again.

I’m basically echoing what has already been stated, but this is exactly what I’ve found in cleaning the roaster. After my first TRUE deep clean (i.e. everything that’s safe to touch, including the underside of the roaster) the amount of air flow that was now available for the roaster resulted in my roasts running significantly colder.

I now have a standard rule that after a maximum of 20 roasts / 40# (running 2# / roast cycle), I perform the same deep clean to make sure air flow does not change like that again.

KEEP IN MIND: I live in Western TN, and we’ve had some significant humidity and weather shifts recently. Sometimes, even after a deep clean, I find myself combatting the other end – too much heat. If you are noticing shifts to increased humidity, that’s going to allow heat to conduct more effectively through the air, resulting in elevated roasting temperatures.