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Permalink Reply by Michael McIntyre on November 12, 2013 at 8:21am

I worked on an ancient IR-24 for a while, and it cooled a full batch in 7 minutes or so. We felt our full batch capacity was 28-32 lbs depending on the coffee and roast degree, but we had 2 infrared tiles where I believe some newer models have 3. Plus we were roasting perhaps a little faster than is typical on Diedrichs, so we needed as much efficiency as we could build. I think many might argue against cooling and roasting at the same time for the fact that there is only one fan that directs airflow through the drum and through the cooling bin. However, the Diedrich design allows you to control dampers between the two, unlike the early model Ambex YM 15 I worked on for a couple years. It was a constant airflow, regulated by gas flame level. I think the main key to a Diedrich operating well, or any roaster for that matter, is to keep it super clean. Hope that helps.

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Permalink Reply by Chad Kimm on November 19, 2013 at 2:12pm

Yes, you can start a new batch while the previous one is cooling with a Diedrich.  

All air supply enters the roaster through the cooling tray.  The mechanical 'flap' inside allows you to divert that air through different parts of the roaster.  There is the reality that total air flow through the machine will be restricted if the cooling tray is full of coffee and it's up to your profile to determine whether that is effecting what you're trying to do with a particular coffee.  In general air flow through the drum is restricted during the first part of the batch anyway and the air flow control is switched to cooling bin already.

We tend to start a new batch as soon as our drop temp gets back to were we want it.  With the coffee in the cooling tray, we let the agitator run for a minute or two and then shut it off.  The coffee cools much quicker if the agitator is stopped.  You don't want to do this too soon since the hot screen can potentially scorch the bottom layer of coffee. We do brush back the coffee that is over the dump chute since that spot doesn't have air flow. After 5 or 6 minutes the coffee in the cooling tray is cooled and can be dumped before other air flow changes need to be made.  

I will completely agree with Michael, keep the entirety of your exhaust path clean. Air flow restrictions through a Diedrich will have noticeable affects on your flavor profile.

Chad  

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Permalink Reply by Mike McGinness on November 20, 2013 at 9:42am

I roast on a different roaster with single fan motor for cooling and drum flow. I also cool while roasting and have designed my all profiles accordingly. To equalize the first batch of a session I keep a tub of old beans to toss in the cooling tray.

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Permalink Reply by Chris Molieri on November 20, 2013 at 11:07am

Michael, Thanks for the information. I am not sure if this model has 2 or 3 or more burners than yours does. I know it was built in 1997. Going only up to 32 lbs on a 24 kilo sounds a bit low, I'm wondering why you couldn't do 50 pounds?

Chad, thanks for sharing. I see your point on the air flow being needed inside the drum later in the roast rather than in the beginning. 

Mike, I wonder if there is another way to equalize a batch rather than " keep a tub of old beans to toss in the cooling tray".

Thanks all! 

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Permalink Reply by Mike McGinness on November 20, 2013 at 11:21am

Probably but why complicate the matter. The goal is to have the same airflow first batch as subsequent batches when a batch is in the tray cooling. Simple solution that has worked for years put beans in the tray first batch.

Chris Molieri said:

Mike, I wonder if there is another way to equalize a batch rather than " keep a tub of old beans to toss in the cooling tray".

Thanks all! 

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