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Thread: Behmor Temperature profile

  1. #1
    Senior Member brettreaby's Avatar
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    Behmor Temperature profile

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    This is a graph of a roast i did today: i have positioned the thermocouple hard against the interior ( where the lower element thermistor is fitted.

    Details P1, 330g beans, D, 1lb, C1 @10, no C2.

    So my point is that using the inbuilt P1 ( which is meant to be full power after build up , you can see that the power is in fact 1100W ( from the rear element ) for the first 10 minutes and then 500W from the top element. The problem is that because the top element also comes on with the fan, the temperature struggles to stay around 200 degrees and gets down to 100 just before shutoff.

    i will try P2,3,4,5 but the instruction leads me to believe these will all be similar.

    I am convinced the logic of behmor is flawed and probably driven by safety concerns.





  2. #2
    CoffeeSnobs Owner Andy's Avatar
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    Re: Behmor Temperature profile

    Quote Originally Posted by 2B3B2C3D3D3B2C282B30490 link=1326615150/0#0 date=1326615150
    you can see that the power is in fact 1100W ( from the rear element ) for the first 10 minutes and then 500W from the top element
    Interesting but also very wrong.

    The two elements are 115v each in series so both are getting the same power.

    If all you want to do is to see when the elements come on and off then get a sparkie to put an ammeter inline with the elements and it will show you the cycle.

  3. #3
    Senior Member brettreaby's Avatar
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    Re: Behmor Temperature profile

    Not wrong : you are misinterpreting my post.

    the bottom element(s) are 2 x 115v elements each 550W totalling 1100W and i am calling them the bottom element.

    I am referring to the element on the top of the roaster which draws 500W as the "top element"

    Dont need a sparky I am an electrical engineer plus I am using a $20 gadget which shows the instantaneous current, which can be ~2.8A ( with top element only),
    5.4A ( bottom elements (2) only) or 7.2A with both heater sets together.

    Apart from safety concerns i dont see why the behmor doesnt let the bottom element come back on to maintain the coasting temperature at the nominal 200C.

    looks like i might have to pimp it up a little....








    and there is a 3rd erleemnt

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    Senior Member brettreaby's Avatar
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    Re: Behmor Temperature profile

    .. please ignore the line

    "and there is a 3rd erleemnt "



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    CoffeeSnobs Owner Andy's Avatar
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    Re: Behmor Temperature profile

    Ok, thats a little clearer now.

    What you are calling the top element is the "afterburner", it has nothing to do with roasting the beans. It comes on after first crack and through the cooling cycle to burn the water vapour in the smoke... thus halving the smoke output.

    You can plug the roaster in (without doing a roast) and press "cool" to see it come on with the scroll fan.

    Quote Originally Posted by 39293E2F2F293E3A39225B0 link=1326615150/2#2 date=1326618132
    Dont need a sparky I am an electrical engineer plus I am using a $20 gadget which shows the instantaneous current
    ...which shows the current at the plug. Not the current of the elements. The fans that come on and "ramp up" during different stages of the roast will also be included in the total value seen at the plug.

    As an electrical engineer you already knew that and as a humble coffee roaster I doubt I could tell anything you dont already know even if I think the logic of your testing is flawed.


  6. #6
    Senior Member brettreaby's Avatar
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    Re: Behmor Temperature profile

    Quote Originally Posted by 042B213C450 link=1326615150/4#4 date=1326621754
    ...which shows the current at the plug. Not the current of the elements.
    of course, but the fan current is negligible, the heaters are the main event.

    Now were nearly on the same page can you tell me the logic behind the main heater shutting off at 11 minutes of a 18 minute roast and letting the temperature drop so much?

    Because it seems to me the afterburner heater cannot maintain more than about 100C because it only comes on with its fan.


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    CoffeeSnobs Owner Andy's Avatar
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    Re: Behmor Temperature profile

    Quote Originally Posted by 7060776666607773706B120 link=1326615150/5#5 date=1326627159
    Now were nearly on the same page
    Not even the same book brettly.

    Quote Originally Posted by 7060776666607773706B120 link=1326615150/5#5 date=1326627159
    logic behind the main heater shutting off at 11 minutes of a 18 minute roast
    Ill answer with a question...

    How much heat do I add on a commercial roaster after 1st crack?

    Quote Originally Posted by 7060776666607773706B120 link=1326615150/5#5 date=1326627159
    letting the temperature drop so much?
    Only according to your testing which didnt take into account the bean temperature, the beans going from endothermic to exothermic or the thermal mass of the roast.

    Quote Originally Posted by 7060776666607773706B120 link=1326615150/5#5 date=1326627159
    it seems to me the afterburner heater cannot maintain more than about 100C because it only comes on with its fan
    ::)
    That would be about the temperature that water boils, which is all the afterburner has to do

    (as I said in the above post)....

    Quote Originally Posted by 537C766B120 link=1326615150/4#4 date=1326621754
    It comes on after first crack and through the cooling cycle to burn the water vapour in the smoke
    I can see what you were trying to prove but there are a whole lot more variables in roasting coffee than just the amount of joules going into a roaster.

    Relax with the science and use your senses to get a good roast. I suggest picking a profile (eg: 1 pound, P2) and then adjust the volume of beans to change the outcome.

    When you have a better understanding of the process you can then fiddle with designing a better roaster or maybe determine that adding 200C for the whole length of the roast might not yeild as good a result.

    Its all part of the journey.

    Enjoy
    8-)

  8. #8
    Senior Member brettreaby's Avatar
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    Re: Behmor Temperature profile

    Behmor Coffee Roaster
    Quote Originally Posted by 735C564B320 link=1326615150/6#6 date=1326629316
    Ill answer with a question...

    How much heat do I add on a commercial roaster after 1st crack?

    brettly wrote Yesterday at 22:32:39:
    letting the temperature drop so much?


    Only according to your testing which didnt take into account the bean temperature, the beans going from endothermic to exothermic or the thermal mass of the roast.
    Fair enough I will redo the test with a thermocouple in the airflow top left away from the elements.

    I found this graph which you commented on as a good starting point which shows the temp sits around 200 after C1. So would this be a good airflow type profile?

    Are you suggesting the beans in my graph could still be at ~200C while the internal temp has dropped to ~100?

    PS I am having lots of fun with this but would like to have a good understanding of the science as well.

    I was actually considering the Corretto/KKRoaster path but prefer the applicance look of the Behmor and am very happy with it, would love you to finish your USB interface, any updates?









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