Hey Everyone,

So here the sich, I Roast on a Diedrich IR7, witch is a great machine. I have very little to complain about other that this one issue witch is seeming to be scientific that may only be answered by oogles of hypothesis..... here it goes.

Airflow. Those of us who are familiar, these babys have quite a bit of it. which i, for now, only can assume is awesome. This is the one subject on the Diedrich's that is used, but for now almost used as a hypothesis. Ive talked to quite a few roasters about the airflow and what its intentions, or rather effects on the coffee are. i have not gotten far in terms of information. just allot of assumptions. . . .
So once my search hit the internet, again, assumptions, some scientific information, but not allot in the realm of "here is what i have found" type of information.
Im looking for experience here everyone, so write in and let me know what your trials with these machines has shown in the cup. and feel free to throw in your theories and hypothesis's as well.
I appreciate your help.

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Replies to This Discussion

Hi Lucky,

I am surveying on coffee roaster as well. Found that Diedrich roaster has a infrared gas burner function. What is the really effect on the infrared gas burner compare without the function?

Do you know about Has Granti Coffee Roaster? Any commend? Thanks for sharing.

My experience is that air flow is the fastest responding and most effective control you have on a Diedrich, (i roast on an IR-12.) The indirect heat source means gas adjustments take quite a bit of time to be registered with changes in the drum. Ideally, my gas stays the same through an entire roast, (up to t-minus 10 degrees). My Airflow will give me the real control, starting by building up hot air in the drum, and finishing by forcing excess heat and smoke off the beans.

Keep in mind; the 'cooling bin' and 'drum' functions on your airflow control are not so strict as you might think, the
ratios of airflow are something like 20/80, 80/20, not 100/0, 0/100.

Also, If you kick your control lever several times with force, you may acquire an infinite airflow range, not confined to the 'bin', '50/50' and 'drum' functions.
"I am surveying on coffee roaster as well. Found that Diedrich roaster has a infrared gas burner function. What is the really effect on the infrared gas burner compare without the function?"

IR burners are not an option with diedrich, all series are IR series. Although ten years ago diedrich did produce some direct flame or "atmospheric" roasters. Whats the difference between the two?

IR burners in a nut shell, use less gas, are more efficient at waste, meaning they are cleaner burning, they do this by transferring a % of heat to the drum in the form of infrared wavelength. This is achieved by the ceramic honeycomb type burner. When you look through the sight glass you'll see a brick like burner glowing pumpkin orange with violet dancing on the top. Its fully using all the fuel supplied, as well as radiating infrared heat. Ifr you want to see a picture, I have a pic of a burner disassembled on my photos page.

Direct flame burners, are more old school, are not as efficient but really crank out the btu's. You have a lot more pushing power with DF. The old Gotthotts can do 6min duration at max batch?!?!? wow, a diedrich at max would take 16+min. Anyway they have their pluses and minuses.

I like both, I love atmospheric probats but will always have a special place for that IR12k, great machine.
Air flow in my IR3 is how I control my roast. I try to leave the burners set at one level and change the air flow. I do think though that airflow is not powerful enough to get all the chaf off and out of the drum on my IR3 when I roast Natural Procesed beans. If I open all air to drum to much it slows down the roast to almost a baked point and not roasted, this is also a problem when I have turned the burner too low and it went out and it takes too long to get the heat back to the drum. I love my IR3 for a full batch roast, that is my roasters sweet spot of around a 6.5 pound load in.
I roasted on a late nineties IR 24 for a number of years with my old company and we had to change some stuff around. Keep in mind that Deidrich Roasters have changed since that time but here is my take. Because Deidrich roasters rely on quite a bit on radiant heat they have much lower airflow than other roasters like Probat or San Franciscans but you can control and divert that airflow better than other roasters.
Our roaster would add a bit of nuttiness to every coffee that was roasted in it. All batches were babied and roasted with good ramp curves and great roasting times. It wasn't a big deal because it was very marginal, but still if we roasted a good Brazil or Mexican (which can already be pretty nutty) it would make it almost too nutty. Also that nuttiness would taste a little awkward in some coffees like a wild Java or really fruity Kenya. After about five years the impeller motor broke so when we replaced it we used a motor that had twice the RPMs of the standard motor. That solved the nutty roasting problem but caused some operational problems. First off because we double the airflow it caused our afterburner to malfunction and got us in trouble with our neighbors and the local air pollution authorities. It cost us quite a bit of money to figure it out but we fabricated an adjustable airflow control on the fan cover so that we could fine tune the airflow control by opening up the flap or closing it and restricting the amount of air it could suck up. As you can tell it is pretty hard to explain. It was all worth the pain and money though. Kenyas were fruitier, Guates were more floral, and Nicaraguans never tasted better with clove and nutmeg spicy notes. The increased airflow really brought out the high notes but didn't effect the body or low notes. Unfortunately that cause some difficulty with diagnosing other problems over time because the engineers didnt know what to think of our modifications. Naomi at Tech Support is a champ though so it was all worth it in the end.
wow, a diedrich at max would take 16+min.

hmmmm....I can get to 2nd crack in 9 minutes on an IR-12 without surface scorching, As long as my drum is charged to 440+
Yeh 16 minutes is way to long on a Diedrich! I was doing 7.8 pounds in on my IR3 and was doing 6 to 7 batches in a row of each variety (yes, I have a larger roaster ordered) but I was doing these oversized batches in 12:30 and 12:45 from green dump into drum, to green dump into drum, so I would say my actual roast times were less than 12 minutes! Charge temp in of 430 to 440, medium roast level discharge at 400 to 406 degrees. I am using LP gas though, LP burns hotter than Natural Gas. Are to 50/50 at 265 degrees and to full air through drum at 365. The weights were within .001 of a pound roasted per batch! Extremely consistant!!!

Ian McCarthy said:
wow, a diedrich at max would take 16+min.

hmmmm....I can get to 2nd crack in 9 minutes on an IR-12 without surface scorching, As long as my drum is charged to 440+
I agree, my post was misleading when i wrote it, not sure what I was thinking with the 16min thing. I think I may have been talking about my newish IR3, which had a bad thermocouple on the back plate and was giving me way low temp readings, thus screwing up my charging temps and lengthening my durations. Its fixed now though.

I never had prbs on the 12kilo so I thought it was just lack of pushing power in the 3kilo due to smaller size/ heat absorption of metal. I should have waited to post that last one. Thanks for your info, I agree with you guys about the temp, my 3kilo is a hot machine now,...



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