Heat Exchanger vs. Direct Air Recirculation

Discuss roast levels and profiles for espresso, equipment for roasting coffee.

#1: Post by Jackace »

Howdy, this is my first topic to open, so bear with me!
I recently built a propane fired drum roaster. I'm not yet finished, need to build chaff separator and cooling device. Air is drawn from the bottom past the burner, in the back of the drum, out the front and through the suction fan. Ambient temp in my garage varies from 30 F. to 110 F. so repeatability is an issue.

I would like to build a recirculating system to be able to fine tune the intake temp. Separating the chaff and directly recirculating the exhaust back into an intake manifold would be the simplest, however would smoke/carbon dioxide recirculation have an adverse affect on flavor? The other option would be a heat exchanger after the separator so it would be only fresh air introduced into the intake. It would need a mixing vent after the exchanger for fine tuning temps. I'm not looking for super high intake temps, just repeatable. Efficiency would be a benefit, not the goal.

So my basic question is should I stay away from recirculating smoke back into the roast environment?