Designing a roaster. Heat source?

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

Hi guys,

I'm designing a small 1lb roaster and am debating on which heat source to use. I don't intend on plumbing it in so natural gas is probably not an option. Nonetheless I'll include it for discussion purpose.

So, has anyone here has done tests between different types of heat sources, in terms their influence on flavor? I'm sure there's a wealth of knowledge here :)

Indirect, indirect, airflow driven
propane
butane
butane/propane mix
natural gas
alcohol
electric elements (several types)
infrared
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Bodka Coffee
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#2: Post by Bodka Coffee »

Given the same profiles are used I would hope there wouldn't be a difference in taste between say, gas or electric.

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TomC
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#3: Post by TomC »

Send a pm to member DJR, he doesn't follow the forum daily. But he's built two completely custom gas drum coffee roasters now and I'm sure he'd be a wealth of information too.

His most recent is quite impressive, I haven't been able to see it first hand yet, but it's apparently a Probat style and he even used a water cutter to perfectly create his panels.

I'd link his profile but I'm running around on mobile.
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Marcelnl
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#4: Post by Marcelnl »

Interesting, I'm going to build a roaster too and was also wondering about taste profiles of the various heat sources and designs (perforated drum, closed drum, fluid bed etc).
Have been scroumging The homeroasters forum but have not yet found anything really conclusive (not to say it is not out there).

My starting point is a leftover piece of stainless stove exhaust pipe of 150mm diameter, but could easily revert to any other method as the design should imo follow the best taste results where reasonably possible.
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kaldi61
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#5: Post by kaldi61 »

Complex thing choice of heat source.

If you are not interested in plumbing, or pilot/safety valves, thermocouples, burner design - then natural gas or propane is not for you. Natural gas or propane both burn quite cleanly and don't have a real impact on flavor. If they do, there's a problem with the burner.

Alcohol - small spirit lamps may be ok for small vac pot, but to roast a pound of coffee you would need a pressurized flow to the burner, and alcohol is extremely volatile and a poor choice. It is also very hard to see the flame, and is a bit unsafe because of that. Just think of a pit fire at Indianapolis. Sometimes you cannot see the flames (for real, not just in the Ricky Bobby context).

The camping stoves use a small liquid tank and a pump to pressurize the flow of fuel into the burner. They work very well, can be controlled manually and take almost any fuel you can pour into a tank. Most of those fuels have smell, and their combustion products can affect flavor in a roasted product. I would not suggest that route.

That gets us to electric elements of some form, either a resistive element or infrared. At this point I would defer to others on how to choose.

Or you could go old school and make a wood or charcoal fired system. For a one pound drum, a charcoal fire is not unreasonable, can be small and manageable, but it does have its own set of unique challenges.
-Nelson

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Marcelnl
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#6: Post by Marcelnl »

If the heat source does not influence the taste profile I'm inclined to start off by using a propane camping stove I have rather than going electric though the latter may be more easily controlled with my diy PID...
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