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Enhancing My HotTop (5.1 of 5) ? Extreme Mods
ciel-007
Top  #1 Print Post
Posted on 03/30/2013 11:09 PM
The RAF-1 Extreme (featuring Reversed Air Flow)

When I say "Extreme Mods" I mean modifications that constitute a radical departure from the product originally designed by its manufacturer. A case in point would be a modification that actually reverses the critical direction of the air flow through a Hottop while roasting green coffee beans to near perfection.

The Hottop is arguably the finest ?home? roaster sold on the North American market today. In fact, countless satisfied Hottop owners might wonder why anyone would even consider subjecting such an able roaster to such an extreme mod. I can think of three reasons that might justify trying to reverse the air flow in a Hottop. Namely:

(1) the abundant chaff produced during cracking eventually finds its way to the back of the Hottop where it accumulates to undesirable levels?

(2) the volatile organic compounds that rise from the smoldering beans end up coating vital parts that are neatly tucked away in the back of the roaster?

(3) more importantly, the extreme heat generated in the roasting chamber is pulled into the rear housing where it may cause undue stress to sensitive components over time?

The above reasons are sufficient to prompt some Hottop owners to allege that their favorite roaster is handicapped by a basic design flaw. If so, what might be the incentive to resolve the weakness by reversing the air flow? I can think of three obvious benefits:

(1) Reversing the air flow in the Hottop would eliminate the need to periodically vacuum, or blow away, the chaff that is in constant accumulation in awkward locations astern?

(2) Further, reversing the air flow should eliminate the need to dismantle the roaster on a regular basis, in order to scrub away the stubborn tar-like residues that coat its vital components. Unnecessary dismantling and cleaning tends to be an unpleasant task for most; however, it might also cause premature wear and tear on some components?.

(3) Most importantly, reversing the air flow should reduce the potentially harmful consequences of extreme heat buildup in the housing that shelters the gear box, motor assembly, and delicate electronic circuitry. Hence, the modification should help prolong the longevity of the roaster?s components. This potential benefit is not a trivial one for Hottop owners, like me, who frequently conduct instant, back to back, roasts using high bean-dropping temperatures.

I am pleased to post photos of a modified Hottop featuring a Reversed Air Flow modification. I?ve tentatively called it the RAF-1 Extreme. The most significant difference between a factory Hottop, and the RAF-1 Extreme, is the direction in which the air flows through the roaster. In order to reverse the direction of the airflow, I have installed an extraction pipe above the roasting chamber; that pipe is linked to a plenum mounted at the rear of the roaster; attached to the plenum is the original exhaust fan, which operates in the same way as it does on a factory Hottop.

With this modification, turning ON the exhaust fan creates negative pressure inside the plenum and in the extraction pipe; that negative pressure causes hot gases to be extracted from the roasting chamber through the opening at the top. More importantly, cool air is now pulled into the hot roaster through openings in the rear housing, and openings in the base of the Hottop; this cool air effectively shields the roaster?s most critical components from unpleasant chaff, stubborn tar-like deposits, and extreme heat levels.

Here are photos of the RAF-1 Extreme . Happy Easter!, Ciel
ciel-007 attached the following images:
1_front.jpg 2_side_2.jpg 3_side_2.jpg 4_back_2.jpg
Edited by ciel-007 on 03/30/2013 11:16 PM
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
Randy G
Top  #2 Print Post
Posted on 03/31/2013 1:05 AM
This operates very much like a prototype unit I tested which was an external mockup of the system for the new roaster (not yet available). yours is a brilliant version!

The new rear covers have vent slots in them. I wonder if you could do that so that fresh air circulated in teh read of the machine to keep that area cooler?

Have yo done any quantitative testing to verify that the heat loss is not too great?

Life's too short to drink bad coffee.
 
Web
ronsil
Top  #3 Print Post
Posted on 03/31/2013 3:45 AM
That looks very interesting. Nice idea & well engineered. I'll keep an eye out for your further tests.

I doubt my ability to cope with the engineering but if I can I will give it a try.

Love the idea of extracting the 'muck' away from the rear electronics etc. Currently I am cleaning out the rear area after every 12 roasts. AS Randy says my latest model has additional air vents in the rear cover below the fan.
Ron
 
smico
Top  #4 Print Post
Posted on 03/31/2013 6:38 AM
This is uber-cool-bloody-brilliant looking. I am speechless.

About a month ago I reversed fan incidentally after the cleaning, and I can describe that roasting as high speed driving in reverse. I had to use fan very sparingly because fan would drop the ET instantly. But the main reason I stopped experimenting was smoke that was going out everywhere, mostly through chaff tray.

But I can confirm that temperatures in the electronics area, and of the motor were very low and pretty constant.

Tell us about the profile changes, smoke. There must be much less smoke if you pull most of the chaff away.

Happy Easter.

Miroslav
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
snwcmpr
Top  #5 Print Post
Posted on 03/31/2013 8:27 AM
Very cool.
That would obviously reduce/eliminate smoke residue on the motor.
Very nicely done,
Ken in NC
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
ciel-007
Top  #6 Print Post
Posted on 04/03/2013 12:25 AM

Quote

Randy G wrote:

This operates very much like a prototype unit I tested... yours is a brilliant version! ... Have you done any quantitative testing to verify that the heat loss is not too great?


Randy, thank you for your kind words. That's much appreciated!

Before settling on the final RAF-1 Extreme design pictured above, I experimented with earlier Alpha and Beta Reversed Air Flow designs. The roasting performance of those prototypes was indeed marred by excessive heat loss. For example, here is a photo of an Alpha version with an oversized extraction pipe; this Alpha design was quickly abandoned since the ROR in the BMT was much too slow to achieve SC within a reasonable time frame. Ciel
ciel-007 attached the following image:
alpha-raf.jpg
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
snwcmpr
Top  #7 Print Post
Posted on 04/03/2013 10:17 AM
Ciel,
Nicely done. What are you using as a filter?

Thanks,
Ken in NC
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
smico
Top  #8 Print Post
Posted on 04/03/2013 4:55 PM
Ciel,
Every time I look at this setup I like it more.
Do you collect much of the chaff like in Quest M3, or most of the chaff still falls down to the trey?
Confratulations on the great design.
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
smico
Top  #9 Print Post
Posted on 04/05/2013 5:23 AM
Ciel,
I am not as patient as others...
Did you do any other modification inside of roaster?
I would think that insulation of the back wall make sense now.
Thanks,
Miroslav
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
ciel-007
Top  #10 Print Post
Posted on 04/07/2013 9:38 PM
I should perhaps offer an explanation for my tardiness in replying to earlier queries raised by Randy, Ron, Miroslav and Ken. Before following-up on their posts, I wanted to double check some of the key results emerging from earlier experiments. Over the weekend, I found sufficient time to conduct non-stop roasting trials with the RAF-1. As it turns out, the trials confirmed preliminary findings that were observed using earlier Alpha and Beta versions of the Reversed Air Flow modification to my Hottop. I have tried to capture the most salient recent findings in the summary posted below. Ciel
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
ciel-007
Top  #11 Print Post
Posted on 04/07/2013 9:45 PM
Three Pounds of Great Coffee in 90 Minutes

This weekend, I subjected the RAF-1 to an Extreme challenge - trying to roast a copious amount of great coffee in a modest amount of time. To accomplish this, I roasted Back-to-Back, Non-Stop, for 90 minutes. The end result was 3 pounds of splendid beans destined for some of the finest espresso pulls in town.

My prime objective was to find out if roasting in such an extreme manner might possibly subject a modified Hottop to undue stress. The greatest source of stress during non-stop, back-to-back, roasting would appear to come from extreme heat build-up deep inside the roaster. In order to detect early signs of potential stress, I affixed a K probe to the casing of the main motor; the probe thus allowed me to monitor critical temperature changes in the rear housing where the most sensitive components of the roaster are located.

What was the major finding in those trials? The test results confirm that a Reversed-Air-Flow design, such as the one featured in the RAF-1 Extreme, can indeed shelter vital components housed in the rear. More specifically, the temperature measured by the K probe fixed to the motor casing did indeed rise as five successive roasts unfolded. The highest temperature reached on any given trial always occurred when FC (BMT=384F) began. However, as soon as the main cooling Fan was turned ON (Level 1) the temperature recorded by the K probe began to decline. The highest temperatures recorded on the motor casing were during the 5th and final roast; during that roast, the temperature of the motor rose to a high of 169F for a brief time, and then started to decline when the Fan was turn ON. By the time when the beans from this final roast were being ejected from the chamber, the K probe showed a motor casing temperature of 149F.

These encouraging findings suggest that it should be possible to conduct even more than five, back-to-back, non-stop roasts without subjecting the a modified Hottop roaster to undue stress. I am amazed by the realization that the modest roasting capacity of an exceptional "Home Roaster" like the Hottop, might so easily be enhanced to behave much like a small "Commercial Roaster", without showing any outward signs that its stamina might be impaled, or the excellence of its roasts diminished.

Some of you may be wondering if the roasts emerging from those extreme trials were any good; let me assure you that those beans produced exceptional pulls in my Expobar Brewtus II. There are a number of local commercial roasters within driving distance from my home. These commercially roasted beans range in price from about $15 to over $20 per pound. Although my green beans cost a mere $4.50 per pound, the extreme roasting profile described below produces better pulls than any of the fresh, local, commercial beans I have sampled to date. Ciel
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
ciel-007
Top  #12 Print Post
Posted on 04/07/2013 10:03 PM
A Back-to-Back Roasting Profile for the RAF-1 Extreme

Here is the profile I used to prepare espresso beans during five, non-stop, roasts as described above. It is a relatively simple profile given that much of the time is spent at maximum power with the fan turned OFF. However, the Fan and Power settings play a crucial role towards the end when I must slow down the ROR of the BMT, and thus prolong the period between FC and SC.

Back-to-Back Roast 1:
The roaster is turned ON with the following settings:
-Fan is OFF (Level 0)
-Power at Maximum (Level 10)
-Time at Maximum (24 minutes)
-Temperature at Maximum (428F)
-Green beans (290 grams) are dropped when roasting chamber reaches 350F
-When BMT reaches 384F (FC begins), Fan is set to Level 1
-When BMT reaches 405F, the Fan is set to Maximum (Level 4), and Power is reduced to Level 5 (to obtain a 4 minute roasting period between FC and SC).
-For m?lange roasting, the first (of several) partial bean ejection begins when BMT reaches 422F. (bean agitation arm in cooling tray is manually turned ON - using the "bean agitation tray mod")
-Eject button is pushed when BMT reaches 428F (FC begins) to empty roasting chamber
-As soon as the roasting chamber is empty, the roaster is reset to launch the next roast.

Back-to-Back Roast 2:
The roaster is launched (using the "cracking the 165F barrier? mod) with the following settings:
-The bean agitation arm in the cooling tray is manually turned ON
-Fan at Maximum (Level 4)
-Power at Maximum (Level 10)
-Time at Maximum (24 minutes)
-Temperature at Maximum (428F)
-Green beans (290 grams) are dropped when heating element in roasting chamber is seen to glow (temperature inside the chamber will range from 365F to 390F)
-When the beans stirring in the tray are cool to the touch, Fan is turned OFF (Level 0), and the bean agitation arm is manually returned to its default setting (agitation stops)
-When BMT reaches 384F (FC begins), Fan is set to Level 1
-When BMT reaches 405F, the Fan is set to Maximum (Level 4), and Power reduced to Level 5 (to obtain a 4 minute roasting period between FC and SC).
-For m?lange roasting, the first (of several) partial bean ejection begins when BMT reaches 422F (bean agitation arm in cooling tray is manually turned ON)
-Eject button is pushed when BMT reaches 428F (FC begins) to empty roasting chamber
-As soon as the roasting chamber is empty, the roaster is reset to launch the next roast.

Back-to-Back Roast 3: (see details of Roast 2 above)
Back-to-Back Roast 4: (see details of Roast 2 above)
Back-to-Back Roast 5: (see details of Roast 2 above). In the final Back-to-Back Roast, after the Eject button has been pressed, the roaster is allowed to cool the beans, and to come to a full stop automatically.

The above profile was developed on a Hottop KN8828B-2 to produce about 3 pounds of coffee in about 90 minutes. It may require some tweaking for best results on other models. As you can see, I do not roast based on bean color, smoke, smell, etc... (as I have to do with my GC); those signals are imprecise, and lead to inconsistent results that vary considerably from one roast to the next. In my experience, replicating the excellence obtained in an earlier roast is more readily accomplished by monitoring the ROR of the BMT. I have found that a rapid ROR of the BMT to 405F adds boldness, m?lange ejections add roundness, and a 4 minute stretch from FC (384F) to SC (428F) adds complexity. Ciel
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
smico
Top  #13 Print Post
Posted on 04/07/2013 11:38 PM
I am impressed, humbled. inspired...
Congratulations Ciel on superb mod.

The best part is that fan actually cools the sensitive areas, rather than heating it. You get to equilibrium, and run 10 roasts easily.
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
ciel-007
Top  #14 Print Post
Posted on 04/09/2013 10:19 AM
Miroslav, you have more experience than most when it comes to measuring temperature fluctuations of vital Hottop components during roasting. Attached are two photos showing how I proceeded to monitor this issue in my roasters.

The first photo shows what I did to measure the ambient temperature of the cavity where the Main Circuit Board is housed. I drilled a small hole through the Rear Cover of the HotTop; the hole was barely large enough to insert a K probe, and high enough to allow the probe to be positioned about 1 cm above the Board. With the RAV-1 design, temperature fluctuations above the circuit board are no longer an issue during non-stop roasting.

More importantly, the second photo illustrates how I have been monitoring potentially more extreme changes for the motor on my Hottop. The K probe is lodged in a tiny, shallow, hole near the middle of the casing. That is the setup I have been using to monitor thermal fluctuations for the motor during roasting for several months now. Ciel
ciel-007 attached the following images:
1_board_k_probe.jpg 2_motor_k_probe.jpg
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
snwcmpr
Top  #15 Print Post
Posted on 04/10/2013 7:17 AM
Great read.
One comment:
My HotTop has a max time of 25 minutes.
Ken in NC
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
Randy G
Top  #16 Print Post
Posted on 04/10/2013 10:22 AM

Quote

snwcmpr wrote:

Great read.
One comment:
My HotTop has a max time of 25 minutes.
Ken in NC


That was recently changed and I was not notified. There are probably other changes, but minor, and I will alert Michael about that. Sometimes the factory changes things without notifying the Hottop USA so it can come as a surprise to us as well. Roflmao

Life's too short to drink bad coffee.
 
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snwcmpr
Top  #17 Print Post
Posted on 04/10/2013 10:59 AM
I don't suppose that matters really, if you roast that long, I thinks it called baking.

Ken
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
smico
Top  #18 Print Post
Posted on 04/10/2013 3:46 PM
I would love to have longer max time.
I drop beans at higher temperatures so HT count down starts earlier.
If max time is reached, just looping through the settings wakes up the roaster, but this is a bit of anoyance.
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
snwcmpr
Top  #19 Print Post
Posted on 04/10/2013 5:27 PM
I drop at 350 - 375 oven temp. It is either 21:00 or 20:20.
I end anywhere from 9:?? to 7:??.
What is the time when you start that you would need more time?
Ken in NC
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
smico
Top  #20 Print Post
Posted on 04/11/2013 5:11 AM
Ken, you are right, numbers don't add up.
I will have to look at this when I have time.
It must be wrong setup in my HT profile.
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
ciel-007
Top  #21 Print Post
Posted on 04/11/2013 4:45 PM
Speaking of exteme mods, here is a look at the new model that Hottop will apparently be selling very soon...

http://www.hottop...s2013.html
ciel-007 attached the following image:
new-coffee-roaster-3small2.gif
Edited by ciel-007 on 04/11/2013 4:52 PM
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
Barrie
Top  #22 Print Post
Posted on 04/11/2013 7:54 PM
Ciel, you have a continuous flow of interesting photographs! Where did you get the one of the forthcoming model, and what information came with it?
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
ciel-007
Top  #23 Print Post
Posted on 04/11/2013 7:55 PM
Click on this link:

http://www.hottop...s2013.html
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK?NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
smico
Top  #24 Print Post
Posted on 04/12/2013 8:45 AM

Quote

smico wrote:

Ken, you are right, numbers don't add up.
I will have to look at this when I have time.
It must be wrong setup in my HT profile.
It was only a dead-man-button that hits at 410F, and I reach it on regular basis after the first back-to-back roast.

Back to basiscs... Three safety features of the Hottop are:
356F within 8:30 minutes
410F
428F
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
snwcmpr
Top  #25 Print Post
Posted on 04/12/2013 9:49 AM
Ok, that makes sense.
I reach the 410 every time I roast.

Thanks,
Ken
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
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