I have not used a Gene before. People always say it's a hybrid drum/air roaster. To me, it sounds more like an air roaster than a drum roaster, from the heat transfer point of view (hot air as primary heat source), and from taste point of view (emphasis on acidity rather than body). Is this assessment correct?

Not exactly.

Hot air is the "primary heat source" in nearly every drum roaster too. If you rephrase the question to ask whether a Gene is more like a drum or a fluid-bed, the "hybrid" answer makes sense.

Brightness vs body is not an inherent property of contact, convection and/or radiant heat transfer. By and large, speed makes for brightness, and Gene roasts are neither as fast nor bright as many fluid-beds.

Rich

Hi Rich, thanks for your answer.

I understand convection is the primary heat being transferred to the beans, even in a drum... But you're also right that in a fluid bed roaster, the hot air is being heated by the heating element whether it's propane or heating coil, before it hits the beans. Now I have to re-think what is a "true" drum roaster and a "true" fluid bed roaster... The way I think of it is that in a drum roaster, theoretically you can still roast beans without any air flow, and in a fluid bed (at least from what I know) it's not possible. Where would the Gene fall between these two categories? I guess Im' still not understanding how a Gene roaster works, which contributes to my dumb questions...

It's interesting that a Gene roaster roasts a bit longer than a fluid bed. 9:30 FC sounds like a drum roaster profile. I think by that metric it definitely has drum roasting characteristics.

fu11c17y wrote:I understand convection is the primary heat being transferred to the beans, even in a drum... But you're also right that in a fluid bed roaster, the hot air is being heated by the heating element whether it's propane or heating coil, before it hits the beans.

Same in nearly every drum roaster.

The coil or flame heats air as well as the drum. The air goes into the drum. The heated air does most of the work. You can figure which sources do how much work by plugging a lot of measurements into the formula for something called the Rayleigh number.

I'm not sure what is and what is not typical; but for example, Probat says their modern drum roasters are 85% convection, and 15% conduction.

Now I have to re-think what is a "true" drum roaster and a "true" fluid bed roaster... The way I think of it is that in a drum roaster, theoretically you can still roast beans without any air flow, and in a fluid bed (at least from what I know) it's not possible. Where would the Gene fall between these two categories? I guess Im' stillnot understanding how a Gene roaster works, which contributes to my dumb questions.

You're still not getting it -- which is perfectly understandable since no one goes out of his way to make this stuff clear. (Also, your questions are far from stupid.) Short answer: A fluid bed roaster is one in which airflow agitates the beans. A drum roaster agitates the beans with rotation. A Gene does both.

To make the answer a little longer and more complicated -- your understanding that drum roasters supply a great deal more heat by conduction and less by convection in proportion to fluid beds is true, even though the total contribution of convection is greater than conduction in nearly all drums (there are exceptions).

It's interesting that a Gene roaster roasts a bit longer than a fluid bed. 9:30 FC sounds like a drum roaster profile. I think by that metric it definitely has drum roasting characteristics.

I'm not a Gene guy, but understand there's a lot you can do with them. However, compared to even a reasonably sophisticated drum roaster in the same price range, the HT B for instance, there's a lot you can't do.

But that's not a function of fluid bed vs drum. There are some very sophisticated fluid beds on this planet.

I don't want to do much bottom lining about what makes one roaster better than another, because home roasting is as much about personal satisfaction as it is about anything else. You don't need a $14,000 Diedrich to be happy; or even a $1400 Huky.

However, if you want to "profile on purpose," the more agility (power and air) and the more efficient telemetry (accurate, real time BT in particular) your roaster offers the less you'll have to fight the roaster and better able you'll be to plan and execute your roasts.

Rich

Thanks for your patience in explaining, Rich.

Had my HotTop since the original D model came out. Probably 8 or 9 years now. I welded in some larger veins in the drum a few years ago and upgraded my D electronics to the newer B so I have control over the heater and fan without all the mods to the D. Replaced the heating element a year ago. Other than that it just keeps running. I run about 2 pounds a week through it.

Wow! Huge price increase on HTs. $1100!!!

The price-range competitor was the Gene, now it's the Quest.

Rich

Funny how price increases change our perspective. Two weeks ago, I thought these two Hottops were overpriced. Now I find them bargains <grins>.

http://www.sweetmarias.com/sweetmarias/sale-page.html

I think I gave around $350 my HotTop way back in the day, new in box. Been a good investment.

Wow, just realized this thread was still active. Since this is still going I thought I would provide an update on my decision.

A month ago I pulled the trigger on the HT B-K2. It arrived a few weeks ago. I am 10 roasts in and very happy with the decision. Still learning to 'drive' this beast... it is a beast compared to the Crazy Air popcorn popper I upgraded from.

The three main reasons I went with the HT over the Gene: better control, possible modifications for even better control and monitoring, and I can purchase parts in the U.S. and do maintenance at home (I did find Gene parts in Canada).

I am currently sourcing the materials for the HTC+TC4C mod. Can't wait for this next level of monitoring and control.