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Enhancing My HotTop (5.1 of 5) ? Extreme Mods
RAG
Ciel, Thank you so much for sharing the details of your modification and more importantly your experience with it. I believe this is the best mod that can, and should be made for longer life, safety, and better control of the roast is desired. I will be doing this mod in the next couple months. This article and SMICO's alerting me to it's existence has really served to wake me up to some of the possibilities here.

(I decided to put in a firewall behind the roaster back wall immediately. I was going to use a ceramic paint to do this but decide that could draw heat off so I went with a more conventional pad used in race cars.)

Thanks again for this great article.
 
ciel-007

Quote

smico wrote:

Not much to add to this except thank you Ciel. I will post my experience once I get to do this ultimate modification. Regards, Miroslav


Thanks Miroslav. I look forward to hearing back from you as you move forward with your personal version of this mod. With your talent and imagination, I have no doubt that you will come up with a few ingenious tricks that I missed. 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

Quote

RAG wrote:

Ciel, Thank you so much for sharing the details of your modification and more importantly your experience with it. I believe this is the best mod that can, and should be made for longer life, safety, and better control of the roast is desired. I will be doing this mod in the next couple months.


Rag, good luck with your mods. Don't forget to post some photos. 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

Quote

Randy G wrote:

Well thought out and well implemented...


Thanks Randy, I am honored by such accolades... especially given that they come from the expert who wrote THE book on the Hottop. 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

Quote

Randy G wrote:

I may examine my Hottop next time I have some spare moments (in a year or two) when I take it apart. My thought is to reverse the main fan in its housing to provide positive pressure...


A few Hottop owners (including myself) experiemented with this mod some months ago. As it turns out, simply reversing the fan makes for an unwieldy and unpleasant roasting experience... 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
 
Randy G

Quote

ciel-007 wrote:

A few Hottop owners (including myself) experiemented with this mod some months ago. As it turns out, simply reversing the fan makes for an unwieldy and unpleasant roasting experience... Ciel


My Hottop is equipped with the HTC+TC4C computer control and it allows the fan to be controlled in 10% increments. I am thinking that might give enough control to overcome the difficulties of losing heat too quickly.

But right now I am too busy to deal with such mods.

Life's too short to drink bad coffee.
 
smico
I reversed the fan unwittingly, and I can confirm that this was a bumpy ride.
When I realized the error, I left it like this for some time.
Roast control was quite unintuitive. The worst was smoke comming out from chaff collector.
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
ciel-007

Quote

Randy G wrote:

... I believe that it would be an easy matter to make a spacer to mount between the original fan housing and the plenum to allow use of the factory filter to lessen particulate emissions in the roasting area ...



Thanks Randy. Before I began working on the "RAF-1 Extreme" mod, I was already roasting without the original Hottop factory filter. Removing the paper filter was one of the first mods I made after reading your excellent article on "Metal Mesh Filter Replacement for Hottop Bean Roaster" (at EspressoMyEspresso.com). After replacing the paper filter with a wire mesh, I discovered that my Hottop's roasting performance, and capacity, could be further enhanced.

As you know, I roast with my Hottop (and grill with my Kamado) year-round in a special weather-proof area (see photos). While my Hottop is busy (back-to-back) roasting 3 lbs of coffee, any smoke or fine particulates emanating from the smoldering beans are quickly expelled via the large ceiling fan. As a result, I did not seriously consider using the original factory filter during the "RAF-1 Extreme" Mod.

However, if you double check the dimensions of the Plenum in the "RAF-1 Extreme" mod, you will find that the interior is actually large enough to accommodate the original Hottop filter assembly. In other words, one could easily open the top of the Plenum, and slip the original Hottop filter assembly into place, just ahead of the Hottop exhaust fan. Ciel
ciel-007 attached the following images:
1_roasting_coffee.jpg 2_grilling_steaks.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
 
ciel-007

Quote

smico wrote:

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 tray? Congratulations on the great design.


Since I've never roasted with a Quest M3, I cannot compare them. (However, I think that Ginny and John may be planning to post about their Quest M3 experiences soon). The RAF-1 Extreme mod uses the original Hottop exhaust fan, which is not very powerful. Even when the Hottop exhaust fan is set to maximum power (level 4), practically no chaff is aspirated upwards into the Extraction Pipe towards the Plenum. During roasting, 99.9% of the chaff tumbles to the bottom of the drum and to the lowermost portion of the chamber before finding its into the chaff tray. No chaff (or roasting residue) finds its way into the back of the roaster where the motor and electronic components are housed. 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
 
snwcmpr

Quote

No chaff (or roasting residue) finds its way into the back of the roaster where the motor and electronic components are housed.

That is awesome.
You are a master, and have done very well presenting it, too.
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".
 
ciel-007
Now Roasting 3/4 lb Loads - 38% More than Manufacturer Suggests

Here is a revised back-to-back roasting profile for the RAF-1 Extreme. My modified Hottop is now roasting nearly 4 lbs of greens in about 90 minutes. To accomplish that, I run 5 non-stop, back-to-back, roasts. I do not drop the beans until the roasting chamber approaches a temperature of 399F. I am now using loads of 344-346 grams (that's 3/4 lbs of beans per roast). In other words, the RAF-1 Extreme is roasting 38% more beans than the load suggested by the manufacturer for an "out-of-the-box" (unmodified) unit.

Profile for First of Five Back-to-Back Roasts
The RAF-1 Extreme is turned ON with the following settings:
-Fan is OFF (Level 0)
-Power at Maximum (Level 10)
-Time at Maximum (25 minutes)
-Temperature at Maximum (428F)
-Green beans (345 grams) dropped when roasting chamber approaches 399F
-It takes about 12.5 minutes for beans to reach FC
-When BMT reaches 384F (FC begins), Fan is set to Level 1
-When BMT reaches 410F, the Fan is set to Maximum (Level 4), and Power is reduced (as needed) to stretch the roasting time to 4 minutes between FC and SC.
-For M?lange Roasting, the first (of several) partial bean ejection begins when BMT reaches 422F (see "Tryer Function and Partial Bean Dumps During Roasting" posted earlier)
-Bean agitation arm in cooling tray is manually turned ON (see "Manually Activating Bean Agitation in the Cooling Tray" posted earlier)
-Eject button is pushed when BMT reaches 434F to empty roasting chamber
-As soon as the roasting chamber is empty, the roaster is reset, and the next roast is launched (see "Cracking the ?165F Barrier? posted earlier).

The above profile produces excellent Espresso beans. 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

Quote

Randy G wrote:

... you have a wood box and the plastic fan receiving hot gasses and particulates that enter differently than the original design. In case of a chamber fire or flash-over event in the roast chamber, chaff in the wood box could be ignited...



Randy, thanks for raising a good question.

Before posting about this modification, I roasted over 50lbs of beans during several months. The enhanced Hottop was subjected to non-stop, high-temperature, back- to-back roasting for two hour periods at a time. During those intense trials, I did not see evidence of a fire hazard. As you know, the factory Hottop draws quite a bit of chaff into the rear of the housing; I suppose that might pose a potential fire risk as well.

In the case for the RAF-1 Extreme, since no chaff is drawn up the metal Extraction pipe or into the Plenum, the risk of fire appears to be minimal. I used wood (instead of metal) for the Plenum because I am not equipped for tinsmithing. However, to optimize safety, the wood Plenum could easily be rendered fire-resistant by lining it with metal foil. 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
 
RAG
I would think this design infinitely safer than the stock hot gasses and chaff pulled through electronics and plastic. The tar residue buildup along with the chaff left to accumulate and bake in the internals and electronics.


Picked up my 1-1/4" pipe and stainless yesterday. I think I'll build the plenum out of ABS. I was going to replace the fan but decided to just pull the original out of its enclosure and put it in the plenum addition. I'm not concerned with exhaust fumes but I have some charcoal filter and a stock $3 microwave metal mesh I probably will use anyways. I have a bunch of 3" computer case fans and I think I'll add one to the electronics area while I'm at it.
 
smico
Hi RAG,
Have you completed thermal insulation of the back wall.
It would be nice to see some photos.
Thanks in advance,
Miroslav
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
ciel-007

Quote

RAG wrote:

... I think I'll build the plenum out of ABS ...



There are several types of Acrylonitrile Butadiene Styrene materials on the market with varying thermal properties. Some ABS materials are not intended to be used in long term applications where temperatures exceed that of boiling water. Is there a way for you to find out what is the maximum operating temperature of the ABS material you are planning to use? 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
 
RAG

Quote

ciel-007 wrote:

... several types of Acrylonitrile Butadiene Styrene materials on the market with varying thermal properties. .....


I got a sample and tested with hot air gun and seemed ok but your comment made me look up the spec's. Melting point around 225 F flash point 752 F. So you've made me rethink the plenum. Back to the drawing board.(I do have left over thermal blanket I could line the plenum with but kinda cheeezy).

I have not finished the fire wall construction, and time is an issue right now. Need to reassemble the Hottop and do some roasting.

My dremel tool is my metal working tool so I'm limited on metal fab equipment and skill. Made a great top cover for duct out of stainless but didn't take time to make a template and tried to put the duct hole in after with a knockout. Mistake.

Needed to review your article about mod's especially the
165 override . Think I'll switch to a thermocouple in the motor compartment instead of just momentary open.
 
ciel-007
Fire-Resistant Plenum

Quote

ciel-007 wrote:

Quote

Randy G wrote:

... you have a wood box and the plastic fan receiving hot gasses and particulates that enter differently than the original design. In case of a chamber fire or flash-over event in the roast chamber, chaff in the wood box could be ignited...



... the enhanced Hottop was subjected to non-stop, high-temperature, back- to-back roasting for two hour periods at a time. During those intense trials, I did not see evidence of a fire hazard... In the case of the RAF-1 Extreme, since no chaff is drawn up the metal Extraction pipe or into the Plenum, the risk of fire appears to be minimal...

However, to optimize safety, the wood Plenum could easily be rendered fire-resistant by lining it with metal foil. Ciel


Is there an alternative to lining the Plenum with metal to improve its fire-resistance? Yes, I believe there is. One could treat the wood with a fire retardant solution.

That can be done easily at home. Simply dilute 2.5 tablespoons of sodium borate (Borax) in 1 cup water; then apply it liberally to the wood. The goal is to saturate the wood with the solution, and then allow it to dry. This method can be used to make other natural fibers fire-retardant as well. Should chaff ever ignite within a treated Plenum, the inner wood surfaces would begin to smoke, then char; the sodium borate would undergo a critical transformation by the time the chaff would have self-extinguished. More specifically, when subjected to intense heat, the borax is transformed into a "glass-like" substance, which insulates the wood, and allows the natural fibers to char rather than ignite. This "glass-like" substance, in combination with the char, insulates the wood to the point where the wood effectively resists combustion.

In the unlikely event that a bit of chaff might find its way into the Plenum and ignite, the chaff would be consumed, and the fire extinguished, well before the structural integrity of the Plenum would be compromised.

The following link shows how to make, apply and test a Borax fire-retardant solution:

http://www.instru...retardant/
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

Quote

Randy G wrote:

... the rear wall of the roast chamber is now being cooled by cold air entering from the rear. This could affect the function of the thermal fuse in case of a chamber fire as well as possibly affecting the accuracy of the factory temperature sensor (more of a factor for models with the old-style button sensor).


Randy, thanks for raising yet another great question.

After you raised the question, I started paying special attention to the temperature readings displayed on my Hottop's Control Panel. After observing numerous non-stop, back-to-back roasts, I am finding that the readings don't appear to be any different from the temperatures displayed prior to the Reversed Air Flow modification. I searched for reasons that might explain why my "old-style button" sensor (mounted on the "rear wall") would not be affected as you hypothesized above. The explanation I am advancing below is tied to the fundamental design of the roaster.

A close examination of the Hottop's basic design reveals 24 vent openings on the side of the roaster (see box A in photo). With the RAF mod, when the fan is turned ON, a certain amount of cool air does indeed enter the roaster from the new back vent near the Plenum (see B in photo). However, the air flow from the relatively modest back vent is necessarily smaller in comparison to the larger volume of cool air entering through the 24 side vents.

Since the volume of cool air entering the back of the roaster is too low to have a measurable impact on the temperature sensor mounted on the back plate of the roasting chamber, that would imply that the safety of the roaster is not compromised by the RAF modification.

ciel
ciel-007 attached the following image:
24_side_vents.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
 
ciel-007
Improved Extraction Pipe Mount:

In an earlier post, I described a method of mounting the Extraction Pipe above the Roasting Chamber. At that time, the Pipe was simply allowed to rest on top of the metal grid (the only part I kept from the Top Filter); further, the balance of the space around the Pipe was closed by simply dropping a small piece of metal into place.

http://homeroaste...post_46167

Although the above method works well, I have since made improvements that enhance extraction efficiency. The revised method of mounting the Extraction Pipe atop of the Roasting Chamber can be seen in the attached photos. I am now using RTV to fill and close the space around the Pipe, and effectively eliminate any leakages.
ciel-007 attached the following images:
1_improved_extraction.jpg 2_improved_extraction.jpg 3_improved_extraction.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
 
RAG
I noticed the RTV on the front glass in a previous photo. What is the story with that?
 
RAG
Another RAF on the production line. I know it looks striking similar to a used first aide box.
RAG attached the following image:
raf2.jpg
 
ciel-007

Quote

RAG wrote:

... I know it looks striking similar to a used first aide box.


Rag, that's cool.
Have you decided to use a metal box for the Plenum?
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
 
RAG

Quote

ciel-007 wrote:
... decided to use a metal box for the Plenum?
ciel


Yes metal. Thanks for the input. First Aide box is near perfect size. Opens easy, and has a water tight seal. I debated painting it Camo or Red but decided on boring black. Should be roasting this weekend.

So where do you suggest to put the 165 override and tray switches? What would you suggest as next upgrade? (I put the air flow diverter, and temp monitoring as #1 and #2)

(btw...Why the seal on the front glass? )

Still porting my heater/fan control. Decided to try a netduino mini. Looking forward to getting back to that.
 
smico

Quote

RAG wrote:
(btw...Why the seal on the front glass? )

Hi RAG,
Your answer is here: http://forum.home...ad_id=2815. You should read ALL articles in Ciel's series "Enhancing My Hottop" series http://forum.home...rum_id=122
Those series became pretty much the Bible of the Hottop mods.

First aid kit is a great idea. i will have to look for one in Value Village.

Thanks,

Miroslav
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
snwcmpr
If a First Aid Kit works, would you consider a nice lunch box with the Cartoon Character of your choice? I see them all over the place.

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".
 
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