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My days of being dogmatic about roasting are over - Page 4

Postby Ken Fox on Tue Jan 18, 2011 12:22 pm

germantown rob wrote:Ken,

So we are have the opposite problems. I have an email in at tech to see if they think I should increase jet size or increase pressure but now I know doing both will be a mistake. I have full control over 1lb of beans but have to run full 5.2 WC the entire roast to get a kg done in 18min.

I did not purchase the Federal Hose since I did not need 25' of it, I have a very similar setup as yours in the garage. Curious if you got the entire 25' of hose or did they sell you a shorter length?

Rob

Edit: I did 3lbs of beans per batch for the drum seasoning, but I had about of 30lbs of 2-3 year old green beans waiting for the IR-1 to come.


Hi Rob,

I don't think there is anything magical about that Federal Hose product. Diedrich says that "most people using the IR-1 will vent out the window," which is why, presumably, they recommend this flexible hose. For one thing, I don't know what the basis of the foregoing statement is, since my roaster is serial #10 and these things have only been available for a few months . . . . .

I called Federal Hose twice. The first time, I spoke to an unhelpful lady who said they do not sell to the public and I'd have to deal with a retailer or distributor. She gave me the name and number of a retailer who in fact turned out to sell wholly different Federal Hose products but not the Armadillo hose. I called Federal Hose back and spoke with another lady who was very helpful. She offered to cut off whatever length I wanted and to send it to me for ~$20/foot plus UPS (she said that any length over 4 or 5 feet would cost a lot to ship; my impression is that they ship the product to distributors by truck, on a pallet). It took 3 weeks for the 3 feet of hose I bought to arrive.

In the end we used a mixture of venting products off the truck of the installer plus this 3' section of Armadillo Hose. It's a good install but I think I could have done about as well with other stuff my installer had on his truck.

I think I'll have to go down a jet size by summer time since the ambient temperature in the garage will be higher and I'm not sure I could do many back to back 2lb roasts, even, on a low enough setting, to say nothing about being able to do smaller batches.

ken
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Postby germantown rob on Thu Jan 20, 2011 4:39 pm

I have been talking to Jason, one of Diedrich's techs, about a solution to my low gas pressure. He does not feel increasing my jet size is the correct solution, rather it would be best if my gas company would increase my gas pressure. Worst case scenario is I will have to switch the roaster over to propane to have full power.

Good to know about your thoughts on Federal Hose. I had slight concerns not using exhaust pipe rated for such high temperatures. I actually went with class B piping against Diedrich's recommendations.
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Postby Ken Fox on Thu Jan 20, 2011 7:32 pm

germantown rob wrote:I have been talking to Jason, one of Diedrich's techs, about a solution to my low gas pressure. He does not feel increasing my jet size is the correct solution, rather it would be best if my gas company would increase my gas pressure. Worst case scenario is I will have to switch the roaster over to propane to have full power.

Good to know about your thoughts on Federal Hose. I had slight concerns not using exhaust pipe rated for such high temperatures. I actually went with class B piping against Diedrich's recommendations.


Hi Rob,

I had a long conversation with Jeff yesterday morning, who was put on the line for me by the head of production, Naomi. Jeff did the actual final construction and testing of my roaster.

What Jeff told me was that changing the jet out on this roaster is a much harder job than I had thought previously, and that it would probably require that the roaster be sent back to Ponderay to be taken apart and changed. The other thing he told me is that his philosophy is that you can "never have too much" heat availability in a roaster, and that I should consider myself fortunate :mrgreen:

My brief time spent with Stephen (and he was rushed) gave me the impression that they have a very formulaic approach to roasting and I shouldn't deviate from it in using the roaster. Jeff told me that this was not true, that this was not their philosophy, and that you have to do what works to get your desired end result and profile, regardless of what might be an idealized set of instructions such as when to change the airflow settings and the gas flow to the burner. For example, he told me to dramatically lower my charge temperature when roasting "only" a pound of beans; I should not use 400F, I should try 350F.

This sort of stuff is obvious and is exactly the process I went through over the years when modifying profiles I used on my 1lb sample roaster. It is just that I thought I needed to more or less follow the Diedrich "recipe" when using a Diedrich roaster. Jeff said to forget about that idea and to concentrate on what works for me in my roaster in my location.

I discussed venting with Jeff, as I have done more or less what you did, Rob, with class B gas venting. He told me that they could not recommend that for liability reasons, however, if the roaster were his personally he might be tempted to do the same . . . . One thing I have done that you might consider doing if you haven't done so already, is to get a C02 fire extinguisher. I ordered one from McMaster Carr, which was delivered today. In retrospect, that was not an economical purchase. The extinguisher was $45 less than it would have been from Lowes (who does not stock it but will order it for you) however I was charged a whopping $90+ for "hazardous freight" shipping by Fedex freight. If you pick the extinguisher up personally at your local Lowes, you will not have to pay this ridiculous freight charge. All told, it cost me around $235.

It might be in your case, at least as a stopgap measure, that you should reduce the airflow through the roaster during the parts of the roast where it is "heat challenged."

I'm going to test some of Jeff's suggestions shortly and should have a better idea how they will work out.

Good luck.

ken
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Postby Ken Fox on Fri Jan 21, 2011 9:48 pm

I have reached a milestone in my adventures with the Diedrich IR-1; I'm 99% sure that I've finally roasted a batch of coffee that will be at least decent. It was a 1lb batch, which on my roaster is doubly difficult.

Using the suggestions I was given by Diedrich staff on Wednesday, I tried to do one pound roasts on Thursday with difficult results. One thing I learned was that (at least with the exhaust system as I now have it configured) if I have too much air flow through the drum with too low of a burner flame height, that I risk blowing out the burner altogether. Once this happens the safety devices turn off the gas entirely and if you don't catch it immediately you might stall the roast, or at best it's a pain to get the burner relighted. This puts a relatively finite limitation on using the idea of reducing heat input on smaller batches by reducing the flame height and increasing the ventilation simultaneously.

In speaking with people at Diedrich today, and as a result of some web searching, it is very obvious to me that many users of Diedrich roasters are not following Stephen Diedrich's prescribed roasting profile of a slow temperature buildup with first crack occurring at 11-13 minutes and 2-2.5 minutes between onset 1st and onset 2nd. Stephen seems to prefer longer overall roast times than what I have been able to find users of his roasters describing as what they actually do. I've read quite a few online posts now from people doing 13 to 14 minute roasts on Diedrich roasters, with earlier onset of 1st crack, more in line with what I have been doing previously with my 1lb sample roaster.

I certainly have not tried every possible combination of flame height and ventilation in my attempts to roast 1lb of coffee. Surprisingly, the easiest profile to do that does not require continual fiddling with air and fuel and does not risk blowing out the burner much, produces almost exactly the same profile I was doing before with my 1lb sample roaster :mrgreen: This is what I finally did today with one batch of decent beans, which was taken to my "usual" roast level of just before onset 2nd. My old roaster would have shown a final Bean temperature of 434F or thereabouts, whereas the Diedrich shows a BT of 417F, with essentially the same total roast time of around 13:15 minutes and about 4 minutes between onset 1st and the end of the roast. Looking at the beans I can tell that assuming the beans themselves (El Salvadorean from SM's) were good, the roast product should be also. Weight loss from roasting was identical with what I've gotten on my sample roaster -- 380g remain from a 454g charge weight, which equals a roasting loss of 16%.

2lb roasts, in comparison, are very easy to do with this roaster, the way it is set up in my house. I'll try doing a couple of those during the weekend.

I'd run out of practice coffee and some that is to be sent by a greens broker did not yet get shipped, so I contacted a local roaster who's coffee I'd only want to consume in the direst of circumstances. I asked if they had any old past crop beans they wanted to get rid of. The owner kindly offered me some --- at $4/lb. I was about to say that what I wanted was closer to floor sweepings than that, but then I realized that she probably wouldn't know the difference between floor sweepings and what they use regularly, so I decided just to buy enough to be able to run a few more test batches through.

This is all working out to be both fun, and more work, than I had anticipated.

ken
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Postby germantown rob on Sat Jan 22, 2011 12:12 pm

My low gas pressure makes it difficult for me to finish a roast after 1st crack in under 3 min even with 1lb of greens and if roasting 1kg I have to use full gas pressure to get it done in 5min. If and when the gas company gets back to me I hope to solve this and have plenty of pressure and heat. I did ask Diedrich's tech about switching to propane, yes it is possible but would require patients since it is not an easy task. I got the impression that twisting my gas companies arm would be far easier. If someone was to ask my opinion of which gas type to use for home use I would suggest propane for the ease of setup and ease of getting the exact pressure needed for the roaster.
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Postby Ken Fox on Sat Jan 22, 2011 12:34 pm

germantown rob wrote:My low gas pressure makes it difficult for me to finish a roast after 1st crack in under 3 min even with 1lb of greens and if roasting 1kg I have to use full gas pressure to get it done in 5min. If and when the gas company gets back to me I hope to solve this and have plenty of pressure and heat. I did ask Diedrich's tech about switching to propane, yes it is possible but would require patients since it is not an easy task. I got the impression that twisting my gas companies arm would be far easier. If someone was to ask my opinion of which gas type to use for home use I would suggest propane for the ease of setup and ease of getting the exact pressure needed for the roaster.


Being basically scaled down models of their larger roasters, the IR-1 has design issues that would need to be tweaked wherever it would be installed. Larger roasters would also tend to have an afterburner installed for burning off any air pollution and smells that normally come out with the untreated exhaust. The IR burners that Diedrich uses are both more fuel efficient and more finicky than standard open flame gas burners.

Rob and I are learning that the performance of the IR burner is very much related to the air flow, AND that the heat produced in the roaster that is transferred to the beans is determined by the heat production minus the heat exhausted by the airflow system. As currently set up, Rob's roaster is borderline low on the heat available to roast, and mine is borderline high.

In a real roasting plant you would have a technician (or access to one) who knows something about "airflow engineering" -- I believe this is a term that a Diedrich tech used with me in a recent conversation. They would have to balance all of these factors (airflow through the drum, the effects of wind on the exhaust system, the gas flow and heat production where the roaster is located, the effect of the afterburner on the exhaust flow, etc. etc.) in order to get a roaster that had the greatest possible range of adjustability for roasting coffee. Having no such engineer or tech on staff, Rob and I are having to fulfill that role ourselves, with the phone help of Diedrich techs plus any local assistance we can find.

There are advantages and disadvantages of Natural Gas and Propane. The one advantage of Propane would be the ease of regulating the input pressure, although I do not see this as very compelling. I know from my conversations with Jeff, who did the final installation and testing of my roaster, that reducing my input gas pressure to the house would not solve my excess heating problems on my roaster.

In summary, I think the Diedrich IR-1 is probably a more complex roaster to deal with in a home setting than competing drum roasters that use direct flame for heating rather than the indirect heat from an IR burner as in the Diedrich. Being ignorant about this, I did not consider it when I decided to buy the Diedrich IR-1. This might be worth considering for some people contemplating buying a small commercial roaster to install in their homes. On the other hand, these other roasters may well have their own issues, with which Rob and I are not aware of.

Speaking for myself, this IR-1 roaster "reeks" of quality. Given the other choices available to me in this size, 1kg, I would definitely make the same choice, again.

ken
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Postby Gismar on Sat Jan 22, 2011 6:08 pm

I once had the chance to see some roast-profiles from a professional roaster, they were roasting on a Diedrich ir-12. The profiles from this roaster should be comparable to the one you are using. For a full batch they had a charge temp (celsius) 180 C, reached 150 C in approx. 8-9,5 minutes. Airflow 50/50 at 170 C, Full airflow at approx. 5-10 C after first crack. First crack at approx. 200 Celsius. They reduced gas at first crack. The profiles I saw that were for many different types of coffees was all following this pattern. I have tried to use this pattern on my Hr-1 roaster without any success, the coffee seemed overdried with this long time until 150 C. But the turning-point on the Hr-1 is at a much higher temperature, approx. 100-120 C, resulting in a higher average temp within the same time to 150 C. The turning point on the Ir-12 profiles I saw was around 60 C. This means the temperature stays belowe 100 C for quite a while, I recall they reached 100 C in approx. 4-4,5 minutes. This can explain the long drying phase. Not much drying going on below 100 C. Im not sure what the results of these profiles was, but this were from a proffesional roaster. They are following the Diedrich user manual profile, with a late first crack at about 11-13 minutes as I can understand.

Im not telling this because I belive this is the answer to profiling on a Diedrich gas roaster, but it might be interesting to see how proffesionals do profiling on a similar style roaster. If the ir-1 is working as intended, these results should be comparable with the other gas roasters from Diedrich. It is also a shame that the old forum on Roasters Guild still is unavailable, there was whole lot of info about profiling on the Diedrich roaster, I was told that the old forum was going to be public again soon. Check it out when available.
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Postby farmroast on Sat Jan 22, 2011 7:28 pm

Gismar wrote: I was told that the old forum was going to be public again soon. Check it out when available.

This would be nice. I enjoyed posting when they had the public forum. Discussions rarely went that deep but some good tidbits could be had.
FWIW This is a thread on Air Flow from the recent RG members forum
Air Flow
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Postby hbvd2 on Sun Jan 23, 2011 12:02 am

Congratulations on your new Roaster. The Diedrich Ir Series Roasters are really great machines. I too had a similar experiece in conversation that I had with Steve while attending his school in Ponderay a few years ago. After hearing his pationate and well founded experiences and comparing them to my Homeroast experiences at the time, I have concluded that his ideas are based on a much larger scale of operations and probobably very accurate for that scale. He has artisan level skills at machine design and process design at that level are both hard to beat. As far as I could see there are two big differenced in how his roasters are designed. One is the concept of using an internal heat exchanger of fabricated carbon steel just above the burners. Just a guess but I would put them (2) at 125 lbs apiece for an IR-12. Any burner input heat that is not absorbed by the carbon steel drum goes through the baffles in the HX on the path into the endwall and then through the beans along the length of the drum before exiting out the feedchute and back to the blower suction. This feature allows the roaster to maintain about a 20-40 *delta T for the ET over the BT throughout the roast. This makes for a very efficient profile energy wise, but some of the steeper ramps for some profiles are a little tricky to achieve. They strive for about 280 @5 minutes and 340 @10, 380@12, C-1@395-400 @12-13m. This was coupled with AF=50-50% at 270* and 100%@370*.
The shorter finish is complimentry to the longer development from 300-380 which allows a little more time for critical chemistry development. Due to the low delta T there is less need to have a large cutback in anticipation of first. While there is a little difference in their recommended profile I think that you will find this roaster a dream to control once you get the hang of these slight but significant differences. I think the continued refinement of the final development ramp's time frame and rise rate will continue to be key to obtain the taste you desire.
With regard to Roasting Dogma we can only form opinion from what we think we know. If we maintain open questioning minds while trying new concepts and sharing ideas, Dogma may become unecessary.
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Postby Ken Fox on Mon Jan 24, 2011 1:12 am

hbvd2 wrote:Congratulations on your new Roaster. The Diedrich Ir Series Roasters are really great machines. I too had a similar experiece in conversation that I had with Steve while attending his school in Ponderay a few years ago. After hearing his pationate and well founded experiences and comparing them to my Homeroast experiences at the time, I have concluded that his ideas are based on a much larger scale of operations and probobably very accurate for that scale. He has artisan level skills at machine design and process design at that level are both hard to beat. (snippage)

The shorter finish is complimentry to the longer development from 300-380 which allows a little more time for critical chemistry development. Due to the low delta T there is less need to have a large cutback in anticipation of first. While there is a little difference in their recommended profile I think that you will find this roaster a dream to control once you get the hang of these slight but significant differences. I think the continued refinement of the final development ramp's time frame and rise rate will continue to be key to obtain the taste you desire.
With regard to Roasting Dogma we can only form opinion from what we think we know. If we maintain open questioning minds while trying new concepts and sharing ideas, Dogma may become unecessary.


I did a bunch more roasting today, in both 1lb and 2lb batches. I have obviously not had the opportunity to taste what I have roasted, which will happen in the next few days. I am however satisfied with my increasing knowledge of how to manipulate the behavior of the roaster, and with at least the time-temperature and visual roast results I obtained today.

I am utterly convinced that it takes a certain amount of time for all the necessary reactions to occur to properly roast coffee beans in a drum roaster. Similarly, I am convinced that certain landmarks in the roasting process need to occur with some separation between them. What I remain somewhat skeptical about is that a profile with a "slow start and a fast finish" is any "better" than a profile with a somewhat faster start and a slower finish, if both profiles go to the same roast level over the same total period of time. My gut tells me that the results will be a wash, perhaps somewhat better in one case than the other, but that the likelihood of finding an earth-shattering difference in the cup is remote. But I remain open to being shown otherwise.

After my roasting experience today I am convinced that the exhaust setup currently installed for my roaster is a bit compromised by its length and having 2 "elbows" present in the ducting, plus by the intermittent presence of wind on the exhaust endcap where I have it located on the side of my garage. The difficulty that the roaster (actually, the cyclone) has in evacuating the exhaust is what is causing my difficulty in slowing down the early parts of the roast when I roast smaller quantities of coffee. There are several obvious solutions to this problem with the most radical being drilling a new hole through the wall and relocating the exhaust. This keys in well with my earlier description of professional roasting operations having someone on hand with knowledge of "airflow engineering." I haven't yet decided how I will deal with this; if possible I'd prefer to avoid drilling another hole through the wall and reworking the exhaust piping, but I will do it if I have no other alternative.

ken
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