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Oreck XL blower and Popper heating with recirc
ChicagoJohn
I just completed and tested my attempt at something larger than a popcorn popper. Seems to work good, so I thought I?d post details. Thanks to oldgearhead for sharing his experience with using exhaust recirculation with lower wattage electric heat, to allenb for his posts covering heating dynamics, and to BenKeith for his discussion of DIY heating elements.

A $3.99 Oreck XL BB870-AD portable vacuum at Goodwill started this in motion, and I found various parts to go with it at Menards, Home Depot and from previous popcorn popper modifications. The baffled air mixing box and silicone recirc tubes were added after I realized I?d need more heat, the 60? funnel insert after to improve bean motion, and the heating assembly modification to boost wattage up to 1850 at 115VAC.

The system has one Arduino Nano in the control box that continuously monitors the blower motor for outlet temperature and wattage. It activates the contactor which connects the heating PWM to the elements only after a preset minimum motor wattage is selected via the control knob. This prevents accidentally supplying heat without air which would quickly melt the 240?C thermal fuse on the bottom of the heater assembly.

During operation, the Nano alternately displays the temperature of the blower case at exhaust and the motor wattage on the 7-digit LED display. These are input from MAX 6675 and ACS712 modules, respectively. If, for any reason, the wattage falls below a predetermined level, the contactor connecting the heat PWM and coils is immediately opened to prevent overheating. The blower has a SF113E resettable fuse replacing the lower temp one from the OEM. This activates at 113?C, but the Nano also looks for a lower preset maximum and will open the contactor if that is reached. (In normal operation thus far, I have not exceeded 180?F / 82?C, and the OEM fuse was at 80?C. but I think I could go up to 113?C / 235?F for a short period without permanent motor damage.)

The external Nano monitors the RC temperature and sends the data to the computer which plots it on a graph with the target curve to facilitate operation of the controls for tracking. These include the heating PWM, the blower PWM, and a valve allowing ambient air into the mixing box at the bottom. When fully open, about 60% of the air is ambient with the rest coming from the chaff collector exhaust, and this can be adjusted to 100% recirc.

So far in cold weather with ambient 38?F, I was able to complete a 450 gm roast to after 1C and just at 2C in 16 minutes. I?ve done 300 gm in 9 minutes with no problem with warmer ambient temperature, and I?m hoping to reduce the time for a pound when it?s warmer and maybe by warming up the equipment before starting, but I think it?s at least in the ball park.

After in-chamber cooling, the chaff collector lifts off and so does the RC / globe assembly after the draw toggle clamps are opened, allowing the product to be poured into a collection container. There is a red silicone o-ring that rolls up and down to secure the globe onto the RC for discharge or allow it to be removed for cleaning.

I?ll make a video when things warm up here.
ChicagoJohn attached the following images:
chaff-collector-detail.jpg riast-chamber.jpg heater-change.jpg fb-control.jpg blower-and-heater.jpg front-panel.jpg partially-disassembled.jpg roaster-setup_1.jpg

Edited by ChicagoJohn on 03/30/2017 10:10 AM
So many beans; so little time....
 
oldgearhead
Looks like you are in business.
No oil on my beans...
 
renatoa
Great build ! Eager to see "the fountain" :)

What glass is the RC ?

Can you estimate the wattage of the blower ? is a 210W pump for inflatable pool enough for such task ? i.e. 500g of green.
DIY: TO based IR 750g
Moded commercial: Dieckmann RoestMeister, Nesco, popper(s).
TC4ESP, MS6514, USB/Artisan/Apps, PID controllers
Grinder: MBK Feldgrind, vintage PeDe Dienes
Flair, Kompresso, Aeropress, drip, Gaggia Mini
 
oldgearhead

Quote

renatoa wrote:

Great build ! Eager to see "the fountain" :)

What glass is the RC ?

Can you estimate the wattage of the blower ? is a 210W pump for inflatable pool enough for such task ? i.e. 500g of green.

We know that a two-stage, flow-through, vac/spa blower will easily float 500 grams of greens. Why would you try anything else? A typical vac/spa blower will draw six amp/120V at bean cooling speeds and three amps/120V at roasting speeds, or around 720 watts at max speed.
No oil on my beans...
 
ChicagoJohn

Quote

renatoa wrote:

Great build ! Eager to see "the fountain" :)

What glass is the RC ?

Can you estimate the wattage of the blower ? is a 210W pump for inflatable pool enough for such task ? i.e. 500g of green.


The glass is a Coleman lantern globe, around $10 as I recall.
The blower is from an Oreck XL I got at Goodwill for $3.99. I got a spare on eBay for around $20. It is 4 amp, ~ 500 watt.

Kind of cold here and I'll do a video when we get a nice day.
Edited by ChicagoJohn on 03/30/2017 10:11 AM
So many beans; so little time....
 
renatoa
Sorry, there are parts of the world where some things can't be sourced, so I try to figure the raw specs, to find equivalents.
DIY: TO based IR 750g
Moded commercial: Dieckmann RoestMeister, Nesco, popper(s).
TC4ESP, MS6514, USB/Artisan/Apps, PID controllers
Grinder: MBK Feldgrind, vintage PeDe Dienes
Flair, Kompresso, Aeropress, drip, Gaggia Mini
 
oldgearhead
Another point to remember about a vac/spa blower is they usually can deliver 100 CFM and 100 inches of H20 pressure (not at the same time),,
No oil on my beans...
 
coffeeroastersclub

Quote

ChicagoJohn wrote:

Quote

renatoa wrote:

Great build ! Eager to see "the fountain" :)

What glass is the RC ?

Can you estimate the wattage of the blower ? is a 210W pump for inflatable pool enough for such task ? i.e. 500g of green.


The glass is a Coleman lantern globe, around $10 as I recall.
The blower is from an Oreck XL I got at Goodwill for $3.99. I got a spare on eBay for around $20. It is 4 amp, ~ 500 watt.

Kind of cold here and I'll do a video when we get a nice day.


John, the blower you are using (the oreck), are you going to have it draw from any heated recycled air? I ask because I used a few of those in some bean coolers I made and found that they had a very sensitive thermo cutoff switch. Very troublesome. It would cut out in about a minutes time when under what I thought was not really hot air (around 180 degrees F, if that).

Len

Len
"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
 
walt_in_hawaii
John, GREAT build! awesome job, eagerly awaiting the video of it in action! I agree with Len, I had to remove the thermostats in my poppers, their settings would drift and sometimes they'd interfere with the roast, other times they would leave me alone... troublesome when you don't have any idea what they'll do. I've been accumulating parts to do a much larger fluid bed roaster than my P1, but at the same time juggling with my conscience, as I am not sure if the flavors we can get from air roasters vs drums will differ at all... so I bought a small drum just to try it out. My own personal jury is still out on the verdict, not enough time with the various systems yet. But you have done a wonderful job, as usual, judging from what I see there. $3.99 for an Oreck? I think my spa air blower alone was close to $100... although that appears to have been the most expensive part of the fluid bed parts.

aloha,
walt
 
ChicagoJohn

Quote


John, the blower you are using (the oreck), are you going to have it draw from any heated recycled air? I ask because I used a few of those in some bean coolers I made and found that they had a very sensitive thermo cutoff switch. Very troublesome. It would cut out in about a minutes time when under what I thought was not really hot air (around 180 degrees F, if that).

Len

Len


Yes, I am using recirc. The original resettable fuse was 80C. I have replaced it with an SF113e. This was a hand-held portable vacuum and I think that's why the designed it using the 80C one. We'll see :). My temps are getting up to around 180F / 82C so it's not too extreme of a deviation. I monitor it constantly and can set the Arduino shut off point anywhere I want to.
So many beans; so little time....
 
ChicagoJohn

Quote

walt_in_hawaii wrote:

John, GREAT build! awesome job, eagerly awaiting the video of it in action! I agree with Len, I had to remove the thermostats in my poppers, their settings would drift and sometimes they'd interfere with the roast, other times they would leave me alone... troublesome when you don't have any idea what they'll do. I've been accumulating parts to do a much larger fluid bed roaster than my P1, but at the same time juggling with my conscience, as I am not sure if the flavors we can get from air roasters vs drums will differ at all... so I bought a small drum just to try it out. My own personal jury is still out on the verdict, not enough time with the various systems yet. But you have done a wonderful job, as usual, judging from what I see there. $3.99 for an Oreck? I think my spa air blower alone was close to $100... although that appears to have been the most expensive part of the fluid bed parts.

aloha,
walt


Thanks for commenting, Walt. It's fun to experiment, isn't it? :)
I went into the Goodwill (thrift) store looking for used popcorn poppers for spare parts and happened to see this hand-held vacuum sitting there with no attachments or anything and picked it up for $3.99 just for the heck of it. And then one thing led to another, as they say :). The Arduino Nano that monitors the motor temperature and current gives me a bit more confidence I'll be OK with the recirc. My research on vacuum cleaner and other small appliance motors leads me to believe they can take 113C for limited upper limit exposure (around 235F), so I think that in this application anything under 205F will be OK and certainly where I'm running which is just over where the engineered resettable thermal fuse was at, 80C. Time will tell.

If the motor does fail, the Arduino will immediately shut off power to the heating coils. That's why it's there -- the unknown ... :)
So many beans; so little time....
 
allenb
This is a superb build! Lot's of high tech features, looks to be easily taken apart for tweaking the design or cleaning/servicing and should be a fun roaster to operate!

Also looking forward to showtime movie of some green coffee taking a ride. BBQ grill

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
ChicagoJohn

Quote

allenb wrote:

This is a superb build! Lot's of high tech features, looks to be easily taken apart for tweaking the design or cleaning/servicing and should be a fun roaster to operate!

Also looking forward to showtime movie of some green coffee taking a ride. BBQ grill

Allen


Thanks so much for your help and encouragement, Allen. It's always fun to learn and try to solve problems and figure things out And I've found it's even more fun after six cups of coffee first thing in the morning. woohoo
So many beans; so little time....
 
PhilH
Wow - thats very cool ! ThumbsUp

There's a Lot of work gone into that control box too. Well done - looking forward to seeing the roast video.

Are you using Artisan for live datalogging or something else?

rgds Phil
Edited by PhilH on 03/31/2017 5:53 AM
Dalla Corte Mini, Compak K10F, 1.2kg FB LPG/PID FB, 5kg FB LPG/PID
 
ChicagoJohn

Quote

PhilH wrote:

Wow - thats very cool ! ThumbsUp

There's a Lot of work gone into that control box too. Well done - looking forward to seeing the roast video.

Are you using Artisan for live datalogging or something else?

rgds Phil


Thanks. The data acquisition system is serial transfer of temperature from the Nano microcontroller to Excel via free PLX-DAQ and selmaDAQ software. That overlays time-temperature for a roast onto an Excel graph containing the target profile curve, facilitating steering of input parameters. I automated my popper mod with the same system by outputting control of a stepper motor on the heater PWM, but the larger bean mass is so much more stable in the new system and with the broader availability of control parameters -- heater, blower, ambient : recirc ratio -- I think it will be much easier (and more fun) to control manually based upon real-time graphic input.
So many beans; so little time....
 
ChicagoJohn
OGH gave me some operating pointers so I tried another 1 lb today using a preheat of a couple minutes and keeping my ambient air inlet closed to run on 100% recirc. Recirc temp started off around 150?F and ended up at 180?F. I pretty much ran at full power (1725 watts) and it just followed a natural curve -- a bit faster than my target but should be OK I think. I ran at the max of 500 watts on the blower motor until a minute or so before the end when I backed off to 440 watts. Yield was 87% instead of my normal 85% probably attributable to inclusion of the peaberry in this blend. The Yirg was washed.

The time temperature log is attached.
ChicagoJohn attached the following image:
pound-trial.jpg

So many beans; so little time....
 
renatoa
On the other side of the ponds it seems we live with "alternate grams and watts" :) kidding :)
This video shows 500 grams of greens bubbled by that 210W inflatable pool pump I was talking.

[video]https://www.youtube.com/watch?v=DU4J9m9mXfM[/video]


https://www.youtu...U4J9m9mXfM

Quote

We know that a two-stage, flow-through, vac/spa blower will easily float 500 grams of greens. Why would you try anything else? A typical vac/spa blower will draw six amp/120V at bean cooling speeds and three amps/120V at roasting speeds, or around 720 watts at max speed.

Edited by JackH on 04/02/2017 5:09 PM
DIY: TO based IR 750g
Moded commercial: Dieckmann RoestMeister, Nesco, popper(s).
TC4ESP, MS6514, USB/Artisan/Apps, PID controllers
Grinder: MBK Feldgrind, vintage PeDe Dienes
Flair, Kompresso, Aeropress, drip, Gaggia Mini
 
jkoll42
That looks really good. I love that you are using a pitcher for the roast chamber!
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
 
renatoa
Is a French Press glass, with the bottom cut.
DIY: TO based IR 750g
Moded commercial: Dieckmann RoestMeister, Nesco, popper(s).
TC4ESP, MS6514, USB/Artisan/Apps, PID controllers
Grinder: MBK Feldgrind, vintage PeDe Dienes
Flair, Kompresso, Aeropress, drip, Gaggia Mini
 
coffeeforblood
That's quite a project. I hope it works well for you. good post
 
ChicagoJohn
I finally received some fine screen to use in place of the cloth vacuum filter that pretty much clogs up after each roast and has to be replaced with a clean 5" disc. OGH recommended 120 mesh, but could only find 100 mesh so used that. After two successive roasts this morning, it looks clean enough to go at least 5 or so before cleaning. Big improvement in air flow - Thanks OGH!

For some reason my line voltage at max power has dropped from 115VAC to 111, but at ~1600 watts, I'm still able to steer a 300 gm charge along a target profile for both what I prefer for pour-over / cone brewing and the somewhat darker roast my wife likes for her espresso. She prefers roasts that are just into 2C. In this system, in-chamber cooling is very rapid.

I've attached data log profiles for the two I did this morning along with photos that I hope will illustrate differences in color. I decided to throw in a Charbucks espresso roast shot for comparison. After trying Lavazza Super Crema and some previous roasts I did, she says she now notices the charcoal flavors in the Charbucks she'd been drinking for the past 10 years.

I've been getting up to right around 180?F on the blower motor outlet case temperature by the end of each roast running on 100% recirc, nowhere near the resettable thermal fuse or upper limit I set for the microprocessor to monitor. That whole component of the design turned out to have been unnecessary, but I guess it's better to be safe than sorry.
ChicagoJohn attached the following images:
three-roast-comparison.jpg lighter.jpg darker.jpg

Edited by ChicagoJohn on 04/18/2017 10:40 AM
So many beans; so little time....
 
ChicagoJohn
With a 20A autotransformer to boost my line voltage up to 120VAC now, I am working my way up to see what the maximum capacity will be. Today I did a 340 gm Sumatra Mandheling from Happy Mug from a cold start and because the 1C was quite a bit later than I'd been seeing (374?F), I decided to take it a bit longer to about where my wife prefers them for espresso. I did a print-screen on the eee-PC I'm using for data logging.

Maximum blower exhaust temp reached 180?F where it's been running for several previous trials. I used 1.7kW; 14A at 120VAC with about 3A for the OreckXL motor. There is a 20A fuse in the autotransformer and the breaker on this circuit is also 20A.

So everything is looking pretty good and I'll try and make a YouTube video this coming week. Thanks again to all for sharing your experience and ideas which I was able to use to get this far.
ChicagoJohn attached the following image:
sumatra-mandheling-happy-mug.jpg

So many beans; so little time....
 
ChicagoJohn
Counting up my stored runs, I was surprised to find today was my 73rd. Thought I'd post a few pictures and share how things worked out. I'm running this on a 20A circuit and with the recirc typically reaching around 180?F at the motor outlet, I run the heating coils (7.4 Ohm) at 14.8A/118VAC from an autotransformer and the blower motor at 400 watts / 3.3A, just under the 20A curcuit limit (and 20A autotransformer fuse). I've found that I can comfortably process 340 gm of greens (4 runs / 3 lb). I have done 500 gm, but it's a lot more of a balancing act so I've just settled on 340 gm.

Recirc air at the inlet to the heater assembly typically gets up to 160 - 200?F and typically runs around 180?F max. I replace the resettable thermal fuse the OEM used which cut out around 80C with a SF113e and I also monitor it with a Nano programmed to shut everything down if it gets over 205?F. The heating coils are on 20A relay that the Nano controls and will shut down instantly if the heater wattage drops so as to prevent excessive temperature in the heating assembly.

The heating assembly is from a PopLite and I replaced the 30AWG nichrome with 26 in order to reduce the 9.6 ohms for the OEM coils in parallel to 7.4 ohm for higher wattage output.

As I recall OGH saying he does, I basically just start out at full heat and control the roast by blower motor speed and percentage of recirc -- using the valve on the airbox at the bottom. The first roast here, lighter, was run with no preheat. I took the second one up to 415?F and made melange / blend of the wet / dry processed yirgacheffe's.

After a minute of cooling, I remove the chaff collector and let the excess chaff blow off and then disconnect the roasting assembly from the heating coils and motor below and dump the roast into a collecting bowl without removing the globe.
ChicagoJohn attached the following images:
73rd-roast.jpg 72nd-roast.jpg bean-motion.jpg orekxl-based-roaster.jpg roaster_22.jpg

So many beans; so little time....
 
oldgearhead
Way to go, John! You roast pretty much, the same as I do. The recycled heat usually does not exceed 160?F in my roaster is about the only difference i noticed. My used 2-stage, flow-through spa blower has been doing fine with the hot air for several years (6) now. Also note the second and third roasts usually take one minute less time to reach the same roast level as the first.
oldgearhead attached the following image:
bmt_1_9.jpg

Edited by oldgearhead on 09/13/2017 12:42 PM
No oil on my beans...
 
JackH
One of the best roasting setups I have seen John!
---Jack

KKTO Roaster.
 
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