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Thread: Corretto air flow question ?

  1. #1
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    Corretto air flow question ?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    After doing many many corretto roasts using a Breville BB270* which has a small square bin, combined with a Bosch 630 HG, digital temp control 50-630 c with 3sp fan. I keep the bin is 90% covered after 60c and up until the last min before second crack, 220c, then watch and listen.

    My question to other CS members is ,..... Do you* have an opinion as to whether roasts benefit* from using a higher fan speed and lower heat setting on HG , thus providing more air flow to maintain the same temps particularly after first crack ...... If in fact we corretto users are trying to replicate a fluid air style roaster.

    For my first 2 years of using the corretto* I use to back off the temp leading into 1st C and back it off a bit more at first crack and run HG at a slower fan speed ..... So HG temps went from about 580+ c down to 490-520 range on slow fan.......to achieve 3-4 c increase p/min to second crack.

    Now* with a different approach I start to lower my temps as first crack is near , and after first crack I can lower my temps to 360-400 c and still generate my 3-4c p/min increases using fan speed.

    OK so both methods have proved to deliver well roasted beans.

    Can any members offer an opinion as to the benefits of one method over the other ?
    Is more air speed a good thing ?
    Is lowering the temp between first crack and second crack* down to 370 of benefit to beans and roast ?

    Your thoughts would be appreciated...!

    Cheers
    Greg


  2. #2
    Senior Member artman's Avatar
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    Re: Corretto air flow question ?

    Its probably the bean mass temp and its corresponding profile you want to monitor and work on. That way you can see how different heat gun settings (heat/flow) affect things.

    Do you have the CS data logger? It and the roast monitor software is a great tool to see what is happening in real time.

    Cheers

  3. #3
    Senior Member greenman's Avatar
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    Re: Corretto air flow question ?

    Quote Originally Posted by 5A5D46415A5D56320 link=1328489891/0#0 date=1328489891
    Can any members offer an opinion as to the benefits of one method over the other ?
    Is more air speed a good thing ?
    I used to run my Makita HG on full fan speed during roast, I found that this helped keep the beans moving along with the agitation, when I ran fan on slower speeds I occasionally got tipping but going to the highter setting alleviated this problem.
    Running it on the higher fan speed and having the pan enclosed enabled me to run vastly lower heat settings on the heatgun compared to open pan roasting.
    When I reached first crack I just eased back on the heat and watched my temp readings on the roast monitor and adjusted them accordingly until I had reached the roast level that I was trying to achieve.
    Using this method I found that I was able to repeat roast profiles fairly accurately on a consistent basis.
    Taste comparison--I preferred this method to earlier routines as it delivered a much fuller flavour profile :) :) :)

  4. #4
    Senior Member coffeechris's Avatar
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    Re: Corretto air flow question ?

    Hi all,

    Greenman you have just made me realise that i should be using the higher setting on my heat gun. The one i am using has three fan settings, for some reason i automatically started using the middle setting never really giving a thought to the highest setting. Which like you have pointed out could give alot better Air flow while roasting.

    Chris :) :)

  5. #5
    Senior Member artman's Avatar
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    Re: Corretto air flow question ?

    Sorry, should have written what I do. I use an Ozito HG on highest fan speed and heat, it sits a few cms above the hole in the cover in one corner (pointing straight down), the opposite corner of the lid has another hole for the air and chaff to blow out.

    At first crack I raise the gun 2 or 3 cms, leave the fan and heat the same.

    Cheers

  6. #6
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    Re: Corretto air flow question ?

    Thanks Greenman & artman,

    My last 2 weeks of roasting have me convinced that greater air flow speed coupled with less HG temp is producing better results with less divets , ( tipping was not a problem I had ).

    I think using this method is even more important* when using the smaller square BM pans, where there is less agitation and towards the end of the roast some beans can float on top of the bean mass and be subjected to high temps,..... of my old method , compared to lower temps and higher air flow......

    I am now finishing my roasts between* 320-370 c from first crack to second crack with high fan speed and the roast is definitely more even and drinking superbly.

    Funny, only took me 250+ roasts to come to this conclusion ... hmmm !!!

    Greg

  7. #7
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    Re: Corretto air flow question ?

    How about using a water based cooler used in PCs between the fan and the faceplate to add more cooling power? Think very simple refrigerator.

  8. #8
    Senior Member Yelta's Avatar
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    Re: Corretto air flow question ?

    Quote Originally Posted by 5F5843445F5853370 link=1328489891/0#0 date=1328489891
    After doing many many corretto roasts using a Breville BB270* which has a small square bin, combined with a Bosch 630 HG, digital temp control 50-630 c with 3sp fan. I keep the bin is 90% covered after 60c and up until the last min before second crack, 220c, then watch and listen.

    My question to other CS members is ,..... Do you* have an opinion as to whether roasts benefit* from using a higher fan speed and lower heat setting on HG , thus providing more air flow to maintain the same temps particularly after first crack ...... If in fact we corretto users are trying to replicate a fluid air style roaster.

    For my first 2 years of using the corretto* I use to back off the temp leading into 1st C and back it off a bit more at first crack and run HG at a slower fan speed ..... So HG temps went from about 580+ c down to 490-520 range on slow fan.......to achieve 3-4 c increase p/min to second crack.

    Now* with a different approach I start to lower my temps as first crack is near , and after first crack I can lower my temps to 360-400 c and still generate my 3-4c p/min increases using fan speed.

    OK so both methods have proved to deliver well roasted beans.

    Can any members offer an opinion as to the benefits of one method over the other ?
    Is more air speed a good thing ?
    Is lowering the temp between first crack and second crack* down to 370 of benefit to beans and roast ?

    Your thoughts would be appreciated...!

    Cheers
    Greg
    Greg I use a similar setup to you, Breville BM, Bosch 630 HG, and DMM temp probe, top of BM is approx 3/4 covered by a piece of hardiflex with the HG nozzle blowing through a hole in the cover directly into the pan, the resulting airflow blows 99% of the chaff out of the top of the pan, anything remaining is removed by my cooler.
    After a bit of early experimentation I settled on running the HG on med speed throughout the roast, temp varies depending on season.
    My weekly roast at the moment (summer) is 725g of green beans, start everything cold, HG on medium fan, start temp on HG 550c, 1st crack happens @ 200c +/- a couple of degrees every time @ approx 14 mins, at this stage I drop the heat to around 500c perhaps a little less, start watching the roast like a hawk around 220c, depending how it looks I usually stop and cool it between 225 and 230c, total roast time usually 18 to 20 mins.
    Hope this helps. :)

  9. #9
    Junior Member Stephen_Andersen's Avatar
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    Re: Corretto air flow question ?

    Behmor Coffee Roaster
    Using the Breville with an oval pan and Bosch HG..

    I have settled on starting cold and after initial warm up
    Then aim to stabilise the temp at a 10degC per min rise
    up to first crack. This can be by raising/lowering the HG or temp.

    At first crack lower temp then slowly to my Aim Temp.

    No tipping and nice even colours.

    Have always run HG on highest setting and no covers.
    Tried a cover twice but.....struggled with the temps.
    I suppose its what you get used to...how about a pic of your cover.

    I record every 60 sec the following.
    HG Height.
    HG Temp
    Data Log Temp
    Data Log per min change

    See graphs of the above for roast #53.





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