Airflow and ET--specifically on Diedrich IRC-7

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
day
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#1: Post by day »

So, omitting the backstory. Is it possible that a larger more powerful fan used to exhaust the Diedrich out through from the basement to the roof of a 2 story building could cause for excessive air flow and thus reduced temperatures at any given setting?

Laid out as clearly as I can:

1. If the vent is closed-which is actually 20%-- but the fan is twice as powerful--wouldn't that cause the temperature to be cooler at the same flame setting than if the fan were half as powerful?

2.If true, is it possible the roaster would have to roast smaller batches at the increased fan speed due to inability to heat up and maintain full potential at the beginning of the roast?

3. Does anyone know of an effective way to introduce a baffle system or other method of reducing airflow into a Diedrich other than the build in notched system? Something simple that could be added in to test how reduced airflow would affect performance?
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endlesscycles
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#2: Post by endlesscycles »

use a Y fitting to draw makeup air from outside, then a damper of some sort on the leg going to the roaster. Use a pressure gauge to aid in adjusting the damper.
-Marshall Hance
Asheville, NC

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day (original poster)
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#3: Post by day (original poster) replying to endlesscycles »

Thanks a lot! My friend may better understand that! But I am slightly confused. The main thing we are curious to test out is if, because he has too much airflow currently. He might be reducing his load capacity and ability maintain high rors early in the roast at capacity, but that if he could further reduce the airflow could he improve control at higher capacity early in the roast. I personally ally struggled to grasp the idea of a y pipe bringing in make up air from the outside and how it applies to reducing airflow, but it is likely completely my misunderstanding. I can certainly imagine how a pressure gauge based external damper on the intake pipe might could be used, I will have to look at what options are available and how it would fall inline with the system.

Just as a foundation, my best understanding of the process is that with less quantity of air the burners are able to heat that air more effectively before it enters the drum, but on increasing the volume of air passing over the burners the end result is cooler air entering the drum at the same flame setting.
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endlesscycles
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#4: Post by endlesscycles »

Working backwards, High power blower goes to y fitting with dampers, one leg goes to roaster, other goes to make up air. Possible to simply use a damper and no y fitting, but it sounded like the reason for using the high powered blower was to overcome resistance, so keeping the air flowing would help... Just have it come from somewhere other than the roaster so to keep roast air low.
-Marshall Hance
Asheville, NC

day (original poster)
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#5: Post by day (original poster) replying to endlesscycles »

Thanks a lot! I spoke with him today and he is going to check with his HVAC guy and see about options such as these. I was hoping you might have some ideas on how to properly measure the flow of air at various damper settings if something like the y connect took place. I am planning to start a separate thread on a series of related issues but I am a little unclear on what would be the best device to place inline with the damper to precisely gauge that flow and allow for consistency after adjusting.
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endlesscycles
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#6: Post by endlesscycles »

That one has stumped me for a while. Anemometers don't' seem appropriate, but I could be wrong. I think a simple pressure gauge should suffice for most purposes, but will not give an absolute measurement.
-Marshall Hance
Asheville, NC

chang00
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#7: Post by chang00 »

Consider a magnehelic gauge and no-loss stackhead when you speak with the HVAC professional.

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day (original poster)
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#8: Post by day (original poster) replying to chang00 »

Well I will not be talking to him myself, but I will pass the word along. Thank you for the suggestions! If one was using a magnehelic gauge, what would be the benefit in that over tubing in a simple Digital manometer or slack tube mounted near by?

I am reading all I can and have learned a lot, but there are still way more basics I do not know than do.
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