Airflow Adjustment

#1: Post by **mkane** » March 22nd, 2022, 6:02 pm

I've always had this issue with a sagging R0R between 3 minutes & 5 minutes probably due to the fact I don't listen and am a slow learner and have been afraid to touch the fan. I've been set it and forget until yesterday, always with a leaning flame near 90 deg with a setting of 3 on the damper. This roast and many to follow starting with damper @ 1.3, an increase at DE and another just before 1C.

March 22nd, 2022, 6:11 pm

^^^^^^^^^^don't know where that came from. Was supposed to be an image

#3: Post by **EddyQ** » March 22nd, 2022, 7:37 pm

So is a damper setting of 3 a higher airflow than 1.3?

For over 100 roasts I've tweaked my airflow to achieve highest ROR with nearly max gas during these areas needing heat. Then I bring the air lower, gas much lower, a minute or so before FC. My theory is you don't need much airflow once you get the beans hot with plenty of drum heat. All air does after a certain point is dry out the beans. I cannot tell for certainty that my roast flavors have improved or not. But they did not loose flavor and I feel they may have improved a tiny bit. I'm would be curious of your findings.

March 22nd, 2022, 10:02 pm

3 is higher than 1. I keep the fan on high and control flow with the damper. On 1 the flame leans a little. On 3 it leans a lot. I need more flow later in a roast to evacuate smoke. If I don't the coffee will taste like smoke and smell like smoke.

Too much air early in a roast and MET will go through the roof, peaking at 4-5 minutes, and gradually go downhill from there.

I do think airflow plays a role in coffee flavor.

March 23rd, 2022, 8:52 am

image

#6: Post by **LBIespresso** » March 23rd, 2022, 10:14 am

For me, when I stopped changing airflow I had one less thing to manage and found it easier to control AND repeat my roasts. I did not find an appreciable change in my end product either.

I am curious to hear other's experience and eager to learn.

March 23rd, 2022, 11:15 am

Same for me, air flow fixed, gas @max until a fairly fixed point in time (no soak) and stepped decreases of 0.5KPa make my roasts repeatable and I dare say that combination even improve the results in the cup.

I have a hunch that the effect will depend on the themal mass of a roaster as well as it's airflow, so results may well vary across different types of roasters

March 23rd, 2022, 11:59 am

If the airflow is set at max on our machine, it will suck the flame out at the trier and the flame will lift off the burner. Also, max gas will scorch any bean dropped into the drum. Max gas is 3 kPa. I use 1.6kPa and drop beans close to the 10 minute mark. Heat retention in a BC 1 is over the top. It takes 2 hours to cool off after shutdown.

Looking at the above image the last air adjustment created a slight rise in R0R. I won't do that again. I'll stick to 2 adjustments next time.

#9: Post by **Brewzologist** » March 23rd, 2022, 12:53 pm

When I built out my exhaust system and cyclone I used a wind meter to test how it performed. It was interesting but I eventually settled on this lighter trick to set my airflow. All I'm really after is creating a steady flow that is sufficient to remove chaff during a roast. I set it and forget it, except at the very end of the roast where I'll crank up the fan just before drop to evacuate smoke from the drum. I find that when I have a sag/hump it's almost always correctable using gas but acknowledge this is probably dependent on the roaster. Just my .02c

March 23rd, 2022, 2:19 pm

I'm sure I could correct the sag with an increase, but we're not supposed to if you are a follower like I am. Next time I'll stick with less air throughout the entire roast and see if it's still smokey.

Probes are 3mm so it not a probe thing.