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Fan Mod
olddogTim
Has anybody tried reversing the fan in the Hottop so it blows toward the front of the drum? Wouldn't this cool the electronics and keep the chaff out of the rear of the machine?
Tim
Getting old STINKS,but it's better than not getting old (Tim)
Equipment Technivorm model KBT-741 , Aero Press, Aillio Bullet R-1 V-2, running RoasTime
 
ciel-007
Tim, simply reversing the fan produces some undesirable results.
There's a more effective way of reversing the air flow in a Hottop.
It's called the RAF-1 Extreme Mod:


http://homeroaste...post_42291

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
 
turtle

Quote

olddogTim wrote:

Has anybody tried reversing the fan in the Hottop so it blows toward the front of the drum? Wouldn't this cool the electronics and keep the chaff out of the rear of the machine?
Tim


I tried to reverse the fan for 1 roast.

Roast was fine but things got a little hot. Could not grab the chafe tray as it was too hot to touch. Harder to control the roast temp as the back wall of the roaster (where the machine probe is fastened) got too cold too fast.

Back to normal now and taking the back off of the machine to clean out the chafe in there every 4-5 roasts.

Next I am going to try a higher speed higher volume 120mm fan which I will run at a lower speed during roast but at high after the beans are out. Not a lot of hope for success but going to try anyway

I also have a low speed 10mm deep (very shallow) low speed 80 mm fan that I want to put on the louvers at the electronic compartment with an on/off/rheostat or tied into the main fan to blow air into the electronic area. Hopefully this will balance the vacuum that draws in the chafe. Probably going to be another "oh well" adventure but gotta try :)
Mick - "Drinking in life one cup at a time"
"I'd rather be roasting coffee"

Roaster 1: San Franciscan SF-1
Roaster 2: Hottop B-2K+
Roaster 3: 2 kilo Chinese drum
Grinders: Mazzer Major - Forte BG (x3)
Pour over: Hario - Bee House - Chemex - Kalita - Bodum
Drip: Bunn CWTF15-1 & CW15-TC (commercials)
Espresso: Pasquini Livia 90 auto
Vacuum: Cona - Bodum
Press: Frieling - Bodum Colombia
 
turtle

Quote

ciel-007 wrote:

Tim, simply reversing the fan produces some undesirable results.
There's a more effective way of reversing the air flow in a Hottop.
It's called the RAF-1 Extreme Mod:


http://homeroaste...post_42291

Ciel



I am thinking of implementing your mid draft draw fan mod but I want to make the rear box out of sheet metal instead of wood. Not good at prototyping so dead in the water there.

Do you have any measured drawings of your wooden box mod so that a "tin man" could use them to bend and fabricate a sheet metal box out of AC duct metal?
Mick - "Drinking in life one cup at a time"
"I'd rather be roasting coffee"

Roaster 1: San Franciscan SF-1
Roaster 2: Hottop B-2K+
Roaster 3: 2 kilo Chinese drum
Grinders: Mazzer Major - Forte BG (x3)
Pour over: Hario - Bee House - Chemex - Kalita - Bodum
Drip: Bunn CWTF15-1 & CW15-TC (commercials)
Espresso: Pasquini Livia 90 auto
Vacuum: Cona - Bodum
Press: Frieling - Bodum Colombia
 
smico
I reversed the fan inadvertently. It was mighty hard to control the roast, but I left it reversed for some time. Not recommended.
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
ciel-007

Quote

turtle wrote:

... hopefully this will balance the vacuum that draws in the chafe...


Although it's a flawed design, that vacuum still plays an essential role in creating negative pressure inside the roasting chamber. That negative pressure allows fresh air to be drawn in through the top of the chamber; it's also essential for expelling heat, smoke and moisture out the back of the roaster.

A mod that potentially reduces that negative pressure is likely to impact some of those other roaster parameters as well.
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

Quote

ciel-007 wrote:

Although it's a flawed design, that vacuum still plays an essential role in creating negative pressure inside the roasting chamber. That negative pressure allows fresh air to be drawn in through the top of the chamber; it's also essential for expelling heat, smoke and moisture out the back of the roaster.

A mod that potentially reduces that negative pressure is likely to impact some of those other roaster parameters as well.

This has caused me to reconsider my decision to block the top filter with aluminum foil, as I could not see any purpose for it. When I did it a few months ago, I had planned to prick a few holes through the foil if I saw any great change. I did not, and so had left it alone. Recently, with some bean varieties and a larger load than previously (252 < 283g) thanks to acquiring a Variac (thanks again, Ginny), I have noticed moisture droplets on the inside of the rear filter holder when I remove it after Eject. Fern, you have led me to rethink my unintended messing with that negative pressure. Thank you!
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
ciel-007

Quote

Barrie wrote:

... this has caused me to reconsider my decision to block the top filter with aluminum foil, as I could not see any purpose for it...


I agree with you Barrie.

I'm always puzzled to hear about Hottop owners blocking the top filter. When roasting with a regular (non RAF-1) Hottop, the top filter should not be blocked. When BMT approaches 290F, the greens begin to release a large amount of moisture. The Hottop is designed to allow this moisture to escape from the chamber by means of natural convection (no need to turn fan ON). Some Hottop owners wrongly assume that "smoke" is escaping from the top filter at this point; in reality, the Hottop is merely allowing water vapor to escape.

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
Barrie and Ciel,

You helped me to solve long time mystery puzzle: why in the world bean loading chute on the back wall is not closed completely. I think now that moisture escape route is the most probable answer.

My own example supports that theory:
Few weeks ago I have implemented simple modification to close the chute completely, and after that I did have moisture on the back filter.

Moisture on the back filter must be dangerous because some of it probably ends up on the motor and in the electronics area...

But this is no longer issue for me as last weekend I have finally built ad-hoc RAF that is so ugly that I am ashamed to show it. First roast was successful though?

I have some other mods that will be documented soon.

Thanks again for opening my eyes.

Miroslav
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
ciel-007

Quote

smico wrote:
... you helped me to solve long time mystery puzzle: why in the world bean loading chute on the back wall is not closed completely. I think now that moisture escape route is the most probable answer...



Miroslav, thanks for sharing. It took me a while to discover how important it was to allow moisture to escape from the Hottop roasting chamber after BMT reached 290F. The RAF-1 mod project allowed me to discover (and actually SEE) new frontiers in roasting.

http://homeroaste...post_50706

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
 
Barrie
In retrospect, one might ask oneself why the manufacturer would go to the expense of including the top filter if it serves no purpose? Shock
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
ciel-007

Quote

Barrie wrote:

... one might ask oneself why the manufacturer would go to the expense of including the top filter if it serves no purpose?


Barrie, I too would like to be privy to what the engineers were thinking when they designed of the top opening and filter.

In addition to allowing water vapor to escape, I would guess the filter material has the function of slowing down air flow (heat loss) though the large opening, while preventing chaff and particles from escaping the chamber, among other things ...

In other words, I would hypothesize that the filter (on an unmodified factory Hottop) does indeed play a strategic role during roasting, and that it must be kept clean.

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
 
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