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Homeroasters - Home Roasting Coffee Community » BUILDING A ROASTER » Drum Roasters

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Exhaust Airflow
coffeeroastersclub	#21 Posted on 12/22/2017 5:18 PM
Pounder Posts: 535 Joined: May 26, 2009	It does not use a squirrel cage fan either, plus there is an outer fan that attaches to the motor shaft (you can see it in the caged area under the motor prior to main fan housing) that keeps that area cool. "If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
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renatoa	#22 Posted on 12/23/2017 1:39 AM
Administrator Posts: 2409 Joined: September 30, 2016	Right, an impeller. Ok, will look for this motor type for next iteration, we are still in the prototyping phase.


hankua	#23 Posted on 12/25/2017 6:37 PM
Newbie Posts: 21 Joined: March 21, 2011	Here?s another photo of what a heat resistant blower for a coffee roaster looks like: (Sorry photo not uploading) https://1drv.ms/i...DGnBdHsg-w Update: This particular fan is perfect for DIY projects as it?s a 24V version with a built in 5V control wire. They sell an inexpensive control board with a knob, so all you have to do is supply 24V DC. There are a couple of different fan blades available for it as well. I?ve got one on a 400g roaster and have seen one on a 1K roaster and thought it was a stretch but worked well according to his Magnehelic gauge. Edited by hankua on 06/28/2018 10:44 PM
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BobbyS	#24 Posted on 06/28/2018 1:06 AM
1/4 Pounder Posts: 179 Joined: July 02, 2011	Quote allenb wrote: Always leave ample area around the burners for air to flow up, alongside them at very low velocity to ensure you don't cause irregular combustion. There's no known formula that I know of to determine this. You'll know if you have insufficient surface area for the opening if the flame is tossed back and forth and has trouble staying lit. Allen do you think air from the bottom would be enough for two pipe burners, or would it also need side venting?


allenb	#25 Posted on 06/28/2018 5:51 PM
Administrator Posts: 3625 Joined: February 23, 2010	Shouldn't need any side venting and I would recommend against it to lessen chances of unwanted turbulence across the flame. See this post showing a typical Probat with bottom updraft makeup air. https://forum.hom...post_52286 Allen 1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana


BobbyS	#26 Posted on 07/01/2018 12:53 AM
1/4 Pounder Posts: 179 Joined: July 02, 2011	Thanks, Allen!


BobbyS	#27 Posted on 07/02/2018 4:45 PM
1/4 Pounder Posts: 179 Joined: July 02, 2011	Here is a compact blower that I found. In case anyone is interested in a smaller blower. The intake opening is right at 5 inches. It is sold on eBay by a seller through Surplus Center. https://www.ebay....SwFyhaAOHD also this speed control. https://www.amazo...ed+control I wired it into the blower and it has pretty good variable speed. I will know more in about a week when I get it all assembled. Edited by BobbyS on 07/02/2018 4:53 PM


renatoa	#28 Posted on 07/03/2018 1:14 AM
Administrator Posts: 2409 Joined: September 30, 2016	Quote renatoa wrote: Ordered yesterday this fan for my future, design in progress, machine, any thoughts ? https://www.ebay....2605258131 Updates about the above fan. I don't know if the advertised figure of 140 m3/h is true or not and how can be measured, but it is not capable to exhaust all the chaff in a turbo oven design... It could be true though... because when fan is started the temperature inside oven drop about 20C and need more power % pwm to compensate, but the reason could be elsewhere: the turbo oven is a giant cyclone separator itself. Because the fan hole was been placed on the oven lateral wall, the rotating centrifugal speed of the air mass could be more than the fan suction force... I guess the exhaust hole should be on the bottom, where I see chaff landing and forming a vortex. Thoughts? Roasters: DIY: TO based IR 640g Moded commercial: Dieckmann RoestMeister, Nesco, popper(s). Electrics: TC4ESP, MS6514, USB/Artisan/Apps, PID controllers Grinders: Arco, Xeoleo ghost burrs, Krinder, vintage PeDe Dienes, MBK Feldgrind Brew: Flair, Kompresso, Rota Aeropress, Hario Cafeor dripper, Gaggia Mini


coffeeroastersclub	#29 Posted on 07/04/2018 8:07 AM
Pounder Posts: 535 Joined: May 26, 2009	Quote renatoa wrote: Quote renatoa wrote: Ordered yesterday this fan for my future, design in progress, machine, any thoughts ? https://www.ebay....2605258131 Updates about the above fan. I don't know if the advertised figure of 140 m3/h is true or not and how can be measured, but it is not capable to exhaust all the chaff in a turbo oven design... It could be true though... because when fan is started the temperature inside oven drop about 20C and need more power % pwm to compensate, but the reason could be elsewhere: the turbo oven is a giant cyclone separator itself. Because the fan hole was been placed on the oven lateral wall, the rotating centrifugal speed of the air mass could be more than the fan suction force... I guess the exhaust hole should be on the bottom, where I see chaff landing and forming a vortex. Thoughts? I am a bit late to this conversation however I can provide some input. The fan you are referencing is not designed for exhaust gas movement in a pellet stove. It is designed for general air movement (i.e. movement of room temp air through blower then through heat exchanger in pellet stove then out again into room). The following fan is designed for the very hot exhaust gas movement in a pellet stove: https://www.lowes...t/50141134 It does not use a squirrel cage but a different type of air movement fan. The motor is totally separated from the casing and has its own cooler fan built into it. I use this fan for all my large electric roasters. I also use it for a rocket stove I have built for my workshop. It is a really decent fan. Len "If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
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renatoa	#30 Posted on 07/04/2018 8:19 AM
Administrator Posts: 2409 Joined: September 30, 2016	I understand the build difference, but my issues aren't about the heat resistance, but air volume... isn't the airflow figure the same meaning for all... fluid types ? For example about water... aren't 140 liters per hour still 140 liters if pumped by a propeller or a turbine ?


coffeeroastersclub	#31 Posted on 07/04/2018 8:52 AM
Pounder Posts: 535 Joined: May 26, 2009	I thought you were using the fan for exhaust purposes. Am I wrong? "If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
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renatoa	#32 Posted on 07/04/2018 9:24 AM
Administrator Posts: 2409 Joined: September 30, 2016	Yes

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