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Topic: airflow in BBQ (20 msgs / 710 lines)
1) From: Mike Koenig
In trying to nail down what is going on with my drum/BBQ roasting, I'm
trying to isolate what I see as differences in what I'm experiencing,
and what others indicate in their descriptions of profiles and roasts.
One noteworthy fact is that nearly everyone talks about using smell as
a guide for roast progress (since you can't easily see it).  One thing
I notice is that I get relatively little in the way of smell out of my
grill.  (I have to stick my nose pretty close to an opening)  I know
it's not a case of a defective sense of smell, since, with air
roasting I had no problem.
I'm roasting on a Weber gas grill, and I think that these units might
have very little airflow through the compartment.  This would explain
the lack of smell, and the fact that I can easily heat the compartment
to >700 F, whereas I've seen others need to install flashing to
maintain roast temperature.
Anyone have any thoughts on this?  Anyone else use a Weber grill?  I'm
thinking that with low airflow, I'm maintaining a lot of moisture in
the drum, causing my slow early stages of the roast.  Of course, since
I'm at work, this is merely a hypothesis waiting to be tested out

2) From: Michael I
I'm a HG/DB roaster that's now a new RK Drum user, too.  I've done about
half a dozen 1# roasts in the drum on my DCS 75k BTU grill.  My =
are much more similar to yours than to what I've heard from others.  =
you, I can get up to very high temps pretty easily. I'm just at the =
where I'm trying to regulate it so that there's some time between first =
second crack.  My grill retains so much heat, that I have to open the =
for 10-20 seconds during first to bring the temp down.
And, like you, I'm having a bit of trouble with the smell aspect.  There =
some exhaust from the back of my grill -- not the most convenient place =
try to stick your nose.  And coming from the HG/DB, smell and smoke were
major indicators, so I don't think that it's a problem with my sniffer,
The first several roasts that I did came out as quite a mélange.  I'm =
not sure why, since I hit first at about 10-11 minutes on them.  But the
last couple, I've ramped more quickly at the beginning, hitting first at
8:30 or so, and the roast is more consistent.  Sort of the opposite of =
I would have expected.  I'm using the grill's motor, which turns at =
about 6
rpm, and my grill is pretty level (I've checked the bean distribution =
the length of the drum and it's well-distributed).  There's a lot of =
to deal with at the end of the roast, too -- it doesn't just blow away =
it does with the HG.
As far as the taste goes, I haven't had any problems.  I'm currently
drinking a Guat San Jose Ocana, which I'd done as HG/DB, too, and the =
is a little brighter/more fruited in the drum than I recall it being =
from my
notes using the HG.  So I have nothing to complain about from the =
side of things.
The other thing that I've been considering is using the rotisserie IR
burner, instead of or in addition to the main burners.  When I cook
something on the rotisserie, I use only the IR burner, but I have no =
idea if
it would do anything to help or hurt a roast.  I've not heard anything =
anyone else experimenting with that, but if anyone has, I'd be =
in hearing about it.
So I don't really have anything to add to your hypothesis at this point, =
I'm interested in the outcome.

3) From: Homeroaster
My Char Broil grill will hit 700F or more.  If you want smell, you can smell 
my clothes after roasting 5 pounds or more.  I think mine puts out a bit of 
roast smell.
Headed out to roast right now.
Ed Needham
"to absurdity and beyond!"http://www.homeroaster.com*********************

4) From: RK
Mike I had one customer that drilled 2 1" holes in the bottom of his Webber
for better air flow.
Some customers leave the flavor bars and a few have removed them and
replaced them with a steel plate. I have since the beginning, used a 36k
Fiesta and the air flow is great, it has 2 1" holes in the bottom of the
tub, and as far as smells of roasted coffee, not problem it smells up the
neighborhood, when I roast they all come over with a empty bag in hand.
saying refill please

5) From: Mike Koenig
Thanks Ron,
I tried a batch today, removing the grease catcher, and putting my
cooling fan ( a small window fan) on low on the bottom rack a few feet
below the grease hole.  Got more smells, and was still able to
maintain temp.
Of course I broke the cardinal rule of troubleshooting, and also
thoroughly pre-heated the drum, thereby changing two variables at
once.   I did get to first crack at ~ 9 minutes.  We'll see how it
tastes tomorrow.
On 10/12/07, RK  wrote:

6) From: RK
When I do a 1lb batch I reach 1st crack at about 8 min. and then lower the
heat to get 4 min till the 1st snaps of 2nd crack.
2lbs 12 min to first
3lbs 14 min to first
4lbs 16 min to first
these are the targets that I shoot for.
I do preheat the grill and the drum to 500 degrees then lower the temps to
desired target
1lb 430
2lb 465
3lb 490
4lb 510
I use a Fiesta 36k grill 2 burners with a 12ga steel plate for a diffuser
and heat retainer with 1" of space front and rear and 2" of space on each
end. I have one customer that is using a perforated plate that just covers
the burners and says that it improved the flavors over the steel plate and
required about 20 degrees less heat to get to the same degree of roast then
when he was using a steel plate.
Trial and error and changing one thing at a time will eventually get you to
where you want to be, take notes.
Mounting your drum as low as possible in the tub IMO is important I have
mine about 2" off the plate.
Good luck

7) From: Michael I
When you say that it's 4 minutes until 2nd crack, is that from the beginning
of 1st or from the end of it?  In some cases, 1st crack can last for 4
minutes for me, depending on how "rolling" it is.  So, for one pound, is the
total time 12 minutes, or more than that?

8) From: RK
Snip: > When you say that it's 4 minutes until 2nd crack, is that from the
From the begining of first to the desired finish. I roast most of my coffee
to Full City to Vieanna. I have strecthed it to as much as 6 min with good
Ron Kyle

9) From: Michael I
Thanks, Ron.
I just roasted a pound of Kenya AA Kiambu - Kimathi, and am still trying to
dial in a profile that will work consistently.  I got to first at 12 mins,
and second started at 15.  There was about 30 seconds of "silence" between
the end of first and beginning of second.  
So I know I need more heat up front, and then I need to back it off earlier.
I don't have a thermocouple in there, yet, but I know that's my next step in
making results more repeatable (ambient temp of 55 today vs. 80 last time I
roasted clearly introduces another variable).
I did do a press pot of it right out of the drum (as I had run out of
roasted beans -- the horror!), and it was quite tasty.  Not yet the "Fruit
Loops" taste that Tom describes, but sweet, malty, and a good amount of
fruit.  It compares favorably to the last time I roasted it HG/DB.  I'm sure
that as it rests, the fruit and body will develop more, too.
All in all, I'm very happy to be using the drum -- coming from the HG/DB,
it's a pleasure.  After getting the 1 lb roast profile down, I'm eager to
get up to 2-2.5 lbs, as I do have a list of "customers" that I regularly
give coffee to, and bigger batches mean less work for me (and more room in
the stash for new greens).

10) From: RK
You are correct in your thinking, When first get going just a bit I cut the
heat back and let it coast thru first. I cut it about 25 degrees, 1st usally
runs 1 to 2 min. then I shoot for 2 min before 2nd starts if at the 4 min
mark 2nd has not started I raise the heat to high untill the first snap of
2nd then cut the heat to low.
1lb try to get to first crack by the 10 min mark and finish between 13 and
14 min.
Its all about the heat:
Ron Kyle

11) From: James Raven
what type of roaster are you using? I'm interested in a bigger roaster that=
 does more than 9 oz. at a time. Please educate me in a quality roaster wit=
h larger capacity.
Thanks - Jim
Smile & Be Wired
ribes) go tohttp://sweetmarias.com/maillistinfo.html#personalsettingsWindows Live Hotmail and Microsoft Office Outlook – together at last.  =
Get it now.http://office.microsoft.com/en-us/outlook/HA102225181033.aspx?pid=CL10062=6971033=

12) From: Hans von Sichart
hi mike and all,
i also roast with an RK drum on a weber. i have a few thoughts about
the webers and a few questions. don't get me wrong, i love my webers
(i happen to own four) but i noticed a few shortcomings that need to
be taken into account.
1. the webers all seem to have a problem with heat distribution. not
sure how that works physically but somehow the right side of the
barbecue seems to be hotter. when i barbecue meet it fies a lot faster
close to the right. to mess up your trouble shooting even more, you
could move the drum further to the right or the left.
2. Weber thermometers read some numbers that don't seem to match
exactly what is really going on in the grill. i use an older weber
with a red lid and a thermometer is on the far right. i tried my first
roast "by numbers" from he profile son the RK site. beans never
cracked and i had to dump them.
i then i started cranking the grill up to incredible temperatures
(beyond the calibrated thermometer scale) with better results, i
backed down from there after a few roasts and results improved.  i am
now roasting them just a bit above where the scale ends and have some
predictability. not very academic but hey.
after reading your mail on friday i roasted to batches on saturday
opening the sliding grease drip collection unit below and allowed for
more air circulation. first flavor tests gave a cleaner less smokey
flavor but also a hint of bitterness.
- - -
question 1: sometimes my beans develop some oily drips after a few
days of rest. is that normal or is that an indication that i am doing
something wrong? i.e. roast too hot or too long?
- - -
question 2: i noticed that when i roast with lower temperatures the
beans might develop a bitter taste. am i imagining the relation
between bitterness and temperature or is that what's going on.
- - -
question 3: should i put the beans into a cold drum or a hot drum? the
RK site suggests a cold drum, the latest email an pre heated drum.
also recommended on the site when using the 6 pound drum. does anybody
have experience how that might influence the taste?
- - -
question 4: how should we imagine what is actually going on between
the beans, the air and the drum? i imagine a frying pan. potatoes get
soggy when you fry them with a lid on. now in a barbecue, also the
beans might get _smoked_ which changes the flavor, as the air can't
additionally, any moisture in the air also gives the heat more punch -
like in a sauna when they pour water on the rocks. so the beans get
backed quicker but one might not consider that roasting.
question 5: if we increase the air flow, reduce moisture and smoke
what warms the bean? the temperature of the drum? the flame right
under the drum? my webers have three burners. the front and back might
have not much influence on the drum temperature. once the airflow is
question 6: has anybody ever experimented with thermometers that read
the drum temperature? scientifically, that might be the cleanest and
most predicable way to actually get roasting curves into this
a bit more then i intended to write today but these questions were on
my mind and i have no one here to really discuss it with.
kind regards and thanks in advance for your advice.
+ hans

13) From: Floyd Lozano
I'm no expert but will try on some of these:
1) this is normal for a roast that goes full city plus-ish
2) possible you are ramping up too slowly and baking your beans - how long
is it taking to reach first crack?
3) cold drum vs hot - if you are doing small roasts, i suggest cold drum to
slow down the roast a bit.  for big roasts (2lb and up) you want a hot drum
- you don't want to waste time in that case heating up the drum AND the
beans.  for me, this means I reach first crack about 3-4 minutes faster on
larger roasts (i.e. 11-12 min instead of 15-16 min)
4) i am wondering about smokiness too, i think i am getting some of that.
some suggestions:
  - start with a clean grill - vacuum out any chaff from a prior roast
  - find a way to clean out chaff between roasts - this stuff smokes
  - if doing multiple roasts, start with the beans with least chaff!  then
you wont' smoke later batches as much or at all
  - sacrifice some heat retention for ventilation as suggested.  i like the
idea of a fan blowing in the grease trap - going to try that soon.
5) the idea is just enough air flow to move the smoke out.  most grills are
designed for this anyway, else you would have the same smoking effect on
your food.  convection should take care of most of the smoke (hot air rises,
pulls air in from the bottom as it pushed the rising hot air out) but more
smoke means you want to increase this slightly
6) the one shortfall of the RK drum is the difficulty to probe bean mass
temperature.  probing the drum might be possible (quick open of the lid and
hit it with an IR thermometer, but this is a hassle).  Your best bet is to
rely on what the beans are telling you during the roast, with their smells
and the smoke and the sound they make rolling in the drum.  i strongly
suggest familiarizing yourself with these signs by doing heat gun / dog bowl
hope that helps somewhat
On 10/15/07, Hans von Sichart  wrote:

14) From: Mike Koenig
I'm using a homemade drum on my BBQ,  made from an old stainless steel
canister (the kind you might find in a doctor's office full of tongue
depressors).  It's fairly small, but I think I can get it up to about
3/4 pound.   Many of the BBQ roasters on the list are using RK drums
which can do up to four pounds, and are quite nicely built from what
I've seen.
On 10/14/07, James Raven  wrote:

15) From: Mike Koenig
Your experience seems to match mine.  This weekend, I've found that I
need to crank the heat MUCH higher that most of the profiles discussed
here and elsewhere online during the early part of the roast to get to
first crack in under 10 minutes (with ~ 1/2 pound load).  There must
be something going on with the Weber grills to cause the heat transfer
to the drum to be different than many of the other grills discussed.
I can get to first crack in ~ 9 min if I hold the heat at 520 until
first crack.  I will try some higher temps this week and report back.
The Guatemala - Finca San José Ocaña I roasted this way came out
pretty tasty.
I do know that the three burners in the Weber are spaced farther apart
(front to back) than many of the other grills that people are using.
A lot of the others have an oval shaped burner in the center of the
It might have something to do with the effects of the "flavorizer
bars"  (triangular head diffusers above the burner for the non-Weber
folks).  Maybe we are getting primarily radiant heat from the bars
rather than convection to transfer heat to the drum.  (thermodynamics
was never a strong subject for me..)   I'll try without the bars this
week and report back.
The fan below the grease hole seems to improve airflow for me, but
only slightly lowers temperature.  Only a small amount of air makes it
into the hole, and gently blows up through the burners, so it's hot
air that makes it into the grill.
Regaring temperature,  I'm currently using an electronic thermocouple
with a probe tip desinged for measuring air temp (a bead probe in a
sheath with a perforated end).  Now that I've gotten it secure,  it
sits right next to the drum.  The weber dial thermometers are
notoriously innacurate.  After being outside through a few winters,
mine is now about 300 degress off.  They can be adjusted and
calibrated with boiling water, but I'm too lazy to bother.
And speaking of smoky...I spilled a few beans into the bottom of the
grill during one of my roasts,  but didn't clean them out (since the
grill was hot).  During the next roast, they ignited.  I managed to
blow out the flames in the grease pan, but they still glowed red for a
while.  We'll see what effect this will have on the taste.  Maybe this
is a way to get the Charbucks flavor in a city roast...
On 10/15/07, Hans von Sichart  wrote:
ribes) go tohttp://sweetmarias.com/maillistinfo.html#personalsettings<Snip>

16) From: James Raven
thank you for the response Mike, I'm just looking for a larger roaster but =
don't want to step up to some 12 kilo machine, seems they are to big or too=
 small. Looking for something that does about 1-2 lbs. at a time and know t=
hey are hard to find or to get quality info on. But appreciate your respons=
Smile & Be Wired :)
hat does more than 9 oz. at a time. Please educate me in a quality roaster =
with larger capacity.
ribes) go tohttp://sweetmarias.com/maillistinfo.html#personalsettingsBoo! Scare away worms, viruses and so much more! Try Windows Live OneCare=

17) From: Justin Marquez
Was your doctor surprised to come in one morning and find all the tongue
depressors laying around loose on the counter top...?
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On 10/15/07, Mike Koenig  wrote:

18) From: James Raven
guess i need to make an appt. soon and then find out if i'm found out? be t=
agged as a mental patient with container issues? holy stainless steel, my n=
ew religeous item that I need to have to complete my beliefs? Better than t=
heft charges i guess?
hava good
Seattle Jim
From: jjmarquez
To: homeroast
Subject: Re: +airflow in BBQ
Date: Mon, 15 Oct 2007 14:54:06 -0500
Was your doctor surprised to come in one morning and find all the tongue de=
pressors laying around loose on the counter top...?
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On 10/15/07, Mike Koenig  wrote:
I'm using a homemade drum on my BBQ,  made from an old stainless steel
canister (the kind you might find in a doctor's office full of tongue
Help yourself to FREE treats served up daily at the Messenger Café. Stop =
by today.http://www.cafemessenger.com/info/info_sweetstuff2.html?ocid=TXT_TAGLM_Oc=tWLtagline=

Naw, just carry it out...If a nurse or Doc. ask what up with the container
Just tell them you are going for a urine sample and your a homeroaster. The=
might offer you an even larger container.
On 10/15/07, James Raven  wrote:
Start HOT and work your way Down...
Peppers AND Coffee.
(I'm the tall guy in the middle)

20) From: Lynne Biziewski
Spew alert!!!
On 10/15/07, TERRY TITSWORTH  wrote:

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