Fan profiling

[Damian]

Thanks for sharing the zoom meetings.

I found the recent discussions a bit confusing, but anyway, I thought I would share my experiences.
Firstly, I have around 14000W or more heating power, not sure exactly, I have never flat-lined. But can push harder than others might be able to, which was a key point raised in the discussion.

One of the hassles I struggled with was the thermal impact beans have during FC, I could use zones to help offset "dips and flicks", but often it was good for one roast then compounded the issue for another.
With fan profiling, I can reduce the dip effect with higher fan speed, and subsequently reduce the flick reaction. The theory is, the faster flow pushes out the cooler air quicker, maintaining a more constant environment temperature and hence maintaining the roasting momentum.
Since doing this, I haven't needed to use zones and I have not had any baked defects in my beans. I was struggling with these defects for some time. Even though my RoR can look like the heater is chasing its tail at times, more beans are cupping clean of astringent tastes, even without reducing acidity with carbonates.

As for effecting the readings, this really isn't an argument for me. The temperature curve is an estimate anyway, it makes no difference if we calibrate up or down a degree or not, it is the roasting speed and momentum, or shape of the curve that is important. Or more so the ability to be consistent and the repeatability.
In saying that, my FC temperature is pretty well the same for the same beans as when I profile with a slower fan, with the same roasting duration.

Another benefit I find with faster air at the start, it getting the beans up and tumbling will give a more even roast. Too much can cause heating issues and shutdowns, but I find getting the beans moving straight away is important. With some heavier beans and roasts off say 110g+, I find they can be slow to start moving and have resulted in some burnt beans or less even roasts.

Anyway, just giving some of my thoughts for you to consider... and an interesting topic to discuss
Of cause, not all beans behave the same, so there isn't a one size fits all

[Howard W]

Damian would you show us any example fan profile? I haven't tried to modify it so far. Thanks?

Howard

[Damian]

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[Damian]

a short video During FC
https://www.youtube.com/embed/QtJlwzGHUQk

[BenN]

Following. I think this is good idea and I would like to try on next round.

[Steve]

Thats a nice vigorous and compact first crack. Coupled with a relatively smooth / straight decline ROR and the power profile mirrors this without bugging out = clean tasty coffee.

Many roasts ive tried with lower fan profiles and flat or declining power profiles with corresponding ROR do not even crack or its very weak and drawn out crack. This always results in underdevelopment, baked (flat acids / lacks sweetness) and or astringent (light) or bitter beefy (dark) flavours.

That being said im in the final stages of development / testing some profiles in this style (decline ROR and steady increasing power profile) using 90g, a fan profile only slightly faster than the stock Classic but a different shape, closer to that of Droast. This keeps the power requirements under 1300W for a 2nd crack roast and 1250W or less for med - light roasts.

Im not 100% sure yet, need more blind cupping, there may be some positive flavour improvements in using less overall power? But I think using 110g + batch size with higher speed fan likely cancels out this phenomenon which im only speculating is generated by higher power = higher inlet temps depending on fan speed needed to agitate the mass properly?

Anywho these 90g profiles im working on may be useful for people on lower voltage who want to try this style of profile.

Cheers

[Howard W]

Thank you Damian. I have tried raising the fan speed following your profile but I saw that the actual temp curve was about 1 degree below the profile curve which is probably of no significant consequence (? anything to do with having 220V here; not much wobbling in the power curve anyhow). However, the ROR was quite smooth despite having no zone boost! I brewed a V60 immediately after roasting and my first impression was that it had better clarity than using a lower fan speed.

Screenshot (87).png (155.64 KiB) Viewed 13585 times

[mr. bean]

Hi Damien,

Thanks for the explanation - especially regarding reducing the crash and flick around first crack.

I'm wondering if you can still achieve those effects and then start reducing fan speed around 1 min into first crack? It seems to me that's the point at which a lot of people start running out of power (say around 9min).
Obviously you wouldn't get the true 'always increasing power curve', but I wonder if it still matters at that point, so long as the actual bean temp is still increasing?

[Steve]

As I mentioned in the other thread have a look at the med - dark mod ninja turtle fan profile. It is doing exactly what your asking.
First crack tends to only go for 1:00 - 1:20 so after this you can play around with bending the flatline in small amounts to see what that does for power conservation.

The basic thing to remember is you dont want any drastic changes approaching first crack, whether thats the roast profile or fan profie.

[Damian]

I have tried raising the fan speed following your profile but I saw that the actual temp curve was about 1 degree below the profile curve which is probably of no significant consequence (? anything to do with having 220V here; not much wobbling in the power curve anyhow). However, the ROR was quite smooth despite having no zone boost! I brewed a V60 immediately after roasting and my first impression was that it had better clarity than using a lower fan speed.

Screenshot (87).png

IMO, being off the temperature line it is not important, all it means is you reached a particular temperature at slightly different time.
More important is how the FW deals with it. If it maintains the same roasting momentum, great. If getting back to the line causes the roast momentum to stall, then not so good.