Lighter Trick & Roaster Size

[Capuchin Monk]

I did the lighter trick for the exhaust air velocity setting and I'm wondering if there is a minimum roaster size required for such "gauge". My drum roaster is 400g capacity and I set the exhaust air velocity based on the lighter trick seen on Mill City Roaster video. Well, it turned out to be too much for my roaster or at least it appears to be based on bean temperature reaction. I noticed that the trier opening sizes don't vary much between tiny drum roaster like mine and medium size drum roaster +- 2Kg. Obviously, the exhaust volume is much larger for 2Kg roaster than 400g roaster so the suction at the trier opening will be much stronger for 2Kg than 400g if the two have the same trier opening size.

Am I right to think that the lighter trick needs to be offset to some degree for small roasters?

[yakster]

I wonder if you'd need to plug the bean loading port when doing this on your Kaldi Wide 400? Is this a source of airflow into the roaster when you roast? I tried this on the Bullet, but of course when roasting on the bullet you replace the bean loading funnel with a rubber cap to ensure proper airflow. The lighter trick seemed appropriate for airflow with my Bullet with the 600 - 700 gram batches that I roast.

[Capuchin Monk (original poster)]

I wonder if you'd need to plug the bean loading port when doing this on your Kaldi Wide 400? Is this a source of airflow into the roaster when you roast?

It's "plugged" since my (added) bean hopper gate is at closed position.

[Brewzologist]

I did a lot of testing with a wind meter initially to arrive at fan speed settings for my Huky. At any given gas setting, increasing fan speed caused increased temp to a point, after which faster speeds pulled in more air to the drum and temps decreased. The more gas, the faster the fan could go before temps dropped. Of course this is all pretty self evident if you think about it, but all my testing did little to add any precision to my fan settings.

The upshot for me was; use just enough fan to evacuate smoke and chaff from the drum during roasting and leave it there. I found the lighter trick to work well enough for this.

[Milligan]

I don't think I'd rely on it with the smaller roasters. It is a general rule of thumb for larger gas fired roasters, but I'd think most that have a $10k+ machine probably install a $80 manometer on there too.

I did practice roasts at different air flows starting from the manufacturer's "standard roast" protocol. I've currently settled on lower speed during drying to build heat with a bump up after peak RoR or dry end depending on the roast to help stall ET rise during end of Maillard and clear chaff/smoke.