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The Diedrich IR series roasters.

The loyalty of roastmasters for their machines rivals that of car owners. The thing that becomes very clear when talking to coffee roasters is that whatever machine a person roasts on, that's the best, period. It's a lot like cars. You're either a Chevy or Ford man. If you own a Chevy, you'll never own a Ford and vice-versa. For both cars, and the Diedrich roasters, the common phrase of "they don't make them like they used to," is definitely apt. In Diedrich's case, though, they don't make them like they used to because they make them better than they used to.

This is not your father's Diedrich. If there has ever been a company willing to take criticism and use it constructively, practically reinventing its products in the process, it's Diedrich. Originally building small-batch shop roasters for those without large batches of cash, Diedrich has greatly improved its product over the years to become a real contender, with a very loyal customer base.

Talking to Stephan Diedrich, who heads up this manufacturing company, one gets the sense of someone for whom learning is a prime importance. To own and appreciate a Diedrich roaster, indeed, takes a willingness to learn. Roasting coffee, after all, is a business which is knowledge-intensive, yet that knowledge is held tightly to the vests of those who have it, and must be actively sought out by those who don't. The dedicated and serious generally prevail. And as the dedicated and serious search, they'll find that the Diedrich IR series roasters are simple machines to master, making them especially well suited as a first roaster.

A person has to be interested in roasting coffee, though, to appreciate the Diedrich. For the roaster who is eager to learn ever-more about their craft - about coffee's variations from origin to origin, about the way our senses react to the variables in our beloved beverage - for this roaster, one of the Diedrich IR series machines (available in 7, 12, and 24 kilo sizes) could be the right one. With Diedrich's small batch, in-store roasters, the roastmaster has a good deal of control and room for personal experimentation.

For the operator who just wants an in-store roaster because he thinks he needs it to add some sense of show and credibility to his store, but doesn't want to bother with such details as learning how to cup coffee or how the various variables in the roasting process affect the final product, there are better machines. It would be best to move on in search of a more fully automatic machine with plenty of bells and whistles.

Of course, Diedrich Coffee Roasters, based in Sandpoint, Idaho, has built in a mechanism which unintentionally weeds out the non-serious from the dedicated early on in the purchase-decision process: Infrared heat.

The Radiant Energy Myth

There is a common myth about Diedrich roasters that Stephan Diedrich says he'd like to clear up. The myth is that the Diedrichs can't possibly roast coffee effectively because they use radiant heat sources, or more specifically infrared gas burners, which by their nature do not produce hot air, the main component needed to roast coffee. The lazy (or harried) entrepreneur hears a respected colleague repeat this criticism and crosses the Diedrich roaster off his list. The alert roaster would ask himself why on earth a company would market a coffee roaster that can't roast coffee. Clearly seeing the absurdity of the situation, the intent roaster would seek out more information. After all, have hundreds of coffee store owners been swindled without the hint of an uproar?

What he would learn is that the Diedrich does roast coffee effectively and because of the infrared heat source, it will roast cleanly, using less energy than other roasters, while giving more control than many of them over the final output - all this regardless of batch size. One feature that many customers like is the ability to roast any size batch size from 8 oz. to 50 lbs. (obviously a lower maximum applies to the IR-7 and IR-12).

But how does a machine roast coffee without hot air?

It doesn't. The Diedrich roasts coffee with hot air like any other roaster must; how it gets its hot air, though, that is what makes the Diedrich IR series roasters one of a kind.

The heat does indeed come from infrared gas burners. The burners heat the roasting drum and also a heat exchanger, a heavy gauge steel plate that surrounds the drum with steel fins that point inward toward the drum. Clean room air is drawn over the heat exchanger converting the radiant heat to convective heat (hot air) which is then drawn into the drum to roast the coffee.

The advantage to this is that there are two independent heat controls: the burners and the amount of convective heat (controlled by air flow). Essentially this allows the operator to more accurately control the roast time for shorter or longer roasts. It also allows very small batches (as low as 8 oz.) to be roasted in the same roaster, getting the same roast profile as a full capacity roast. A large and small roast can even be done back to back. The burners can be turned off so that the drum doesn't get too hot for a smaller mass of beans, while the convective heat from the heat exchanger still provides the necessary roasting heat that surrounds the beans.

If you tried that in the more conventional roasters with atmospheric (open flame) burners, you'd get some rather disgusting results. Turn the burners off and you lose your convective heat and therefore your roasting ability. Leave the burners on and you scorch those little beans. With the Diedrich, though, you can essentially use your in-shop roaster as a sample roaster and closely match the profile you'll get when you roast at full capacity. This is a bonus for those who don't want to pop for a separate sample roaster. Of course, using the IR-24, with its full capacity of just over 50 lbs. as your sample roaster isn't the most efficient way to go about things, but it is possible. It's a little more feasible with the 7 and 12 kilo models.

Understanding the infrared heat source is integral to understanding how to use the Diedrich roasters. A lack of understanding can lead to some serious puzzlement. One roaster, James Marcotte of Los Angeles, California's City Bean, used to roast on a friend's early model Diedrich roaster, before buying a Probat. He said he always felt insecure roasting on the Diedrich, because there were certain points about it (such as how the air flow worked) that always remained a mystery. The person teaching him how to roast on it, showed him how, but didn't explain why. And, he said, the manual for the early machine didn't help the matter along much. He concedes, however, that the newer Diedrich machines look like they're completely different animals, easier to clean, with different controls and better built parts.

And indeed they are.

In-Store Testing

Diedrich has benefitted greatly from a valuable testing ground, Diedrich Coffee, the retail chain. The retail chain is an entirely different company from the roasting machine manufacturer, but early on they were one in the same, and the retail chain is run by Stephan Diedrich's brother Martin. As all family relationships are testing grounds for what might or might not work in the rest of the world, the retail business provided an excellent arena for research and development leading to various refinements in the roasting machines. It allowed the manufacturer to experience almost first-hand how the machines would be used in a high-volume situation. And like most families, any shortcomings were readily pointed out, everyone becoming intimately familiar with what improvements could be made.

Luckily, Diedrich manufacturing didn't act like a stubborn teenager, tuning out the family's suggestions. It incorporated them, each year making more and more improvements, sometimes making drastic changes mid-season. Everyone was and is welcome to make suggestions. "That's the way my mind works," says Stephan Diedrich. "I'm always looking for some better way of doing something, some improvement, a better part or method of working in the warehouse."

Ease of Use

This constant tinkering has led to a greatly improved machine. There is a stark contrast between the experiences of roasters like James Marcotte, who complained of the early model Diedrich's (more than 10 years old) challenges in the areas of ease of use, access to parts needing to be cleaned, technical support, and strength of parts (he pointed to a worn motor mount, but conceded that the owner of the roaster was perhaps not diligent in his maintenance); and the experiences of the owner of a newer machine, Michael Mitzelfeld, owner and roastmaster at Memphis, Tennessee's Coffee on the Court.

Mitzelfeld, who is fairly new to roasting coffee, bought a new Diedrich IR-24 a little over six months ago and raves about it. "For me, there's just no competition. I turn this on and it's ready to go, up to operational temperature in about two and a half minutes. And the controls are simple for me. I can control everything to get a good roast in the 18 to 21 minutes I'm shooting for, regardless of whether I'm doing half a pound or 50 pounds."

Mitzelfeld says that while he'd heard warnings that the thermostat was hard to read and judge the progression of the roast by, he says that the older machines must have had a different thermometer set up, that his has been extremely reliable and accurate. Diedrich explained that the newer models are different in that regard (as well as many others): The machines utilize a digital thermometer that is located an 1 1/2 inches below the sample trowel so that the thermometer is immersed in the bean mass. Mitzelfeld uses the temperature gauge to tell when the roaster is ready for the beans (around 250 [degrees] F is Mitzelfeld's guideline) so that he can then move the beans from the funnel to the drum and open the airflow into the drum. There are three positions on the air-flow lever: 1) through the cooling bin, 2) 50% cooling bin/50% roasting drum, and 3) through the roasting drum. Mitzelfeld uses the thermostat to gauge whether the roast is progressing too quickly, not quickly enough, or just right and can then adjust the burners accordingly. "It's never let me down yet. It's an easy machine. The first and second pops are very distinct in this machine. You use those and the temperature as a guide and then just pay very close attention to get the roast you want.


Diedrich emphasizes that the IR series of Diedrich roasters has been designed to be as easy to own and use in a retail environment as possible. "Everything on the Diedrich roasters was made to be easily cleanable and serviceable," Diedrich says. This conscious effort was undertaken "to make sure this stuff isn't neglected. If it's harder to clean, the user will be less likely to clean it and that can lead to some real problems."

Mitzelfeld says that his machine is as easy to clean and maintain as it can get. "You have to maintain it, but it is simple to do so," he says.

Parts and service are also easy to deal with. Diedrich says that all parts that are not manufactured by the company directly are U.S.-made and built to international standards. "We stock everything in-house. Plus the parts are interchangeable: the bearings, gear boxes, switches, everything; and available locally from any well stocked industrial supply house. We've made sure of that. Our operational maintenance manual covers all parts so any reputable restaurant equipment service company can replace any part quickly and easily." Calling your local equipment service company usually isn't necessary, though, since Diedrich and others at the company can usually answer any questions you may have and walk you through simple procedures. "I'm always available for a customer and so is our main engineer. We're intimately familiar with the parts and why they're there - how the machine evolved to include each and every part."

The IR 7, 12, and 24 are all ETL listed. They were granted the listing last year, which means much of the tinkering and improvements have been made and the company is finally satisfied with the IR series machines. They are made well from what Diedrich assures are high quality parts. All metals are solid, there are no plated materials in the roasters. Diedrich says he has a philosophy which has led the company to use the best parts universally available. "It is far less expensive for me to invest initially to include the best, high-duty parts that are going to last than it is for me to use lighter duty parts and spend time rectifying problems."

Mitzelfeld relays happiness in the service from Diedrich as well as other areas. Though he reports there haven't been any problems with his machine, he says that the principals of Diedrich are very accessible. "Steve and Becky are great support. Even if Steve is on the road, he'll stop and return my phone call." That kind of service, he said, is truly rare.


If anything, training is the most important factor in whether you'll get the results you want from a Diedrich (or any) roaster, according to Diedrich. Training is included in the price of the roaster and Diedrich highly recommends taking advantage of it. "You have to be taught and learn everything you can about your roasting machine, about coffee, cupping it, everything." He emphasizes how important it is to know how moisture content affects the roast, how the moisture in the beans draws heat, and how with some coffees you'll want to roast quicker than others. Without getting good training and making the effort to understand coffee and the roasting process as well as the particulars of your machine, "you'd be better off getting a good wholesale supplier of roasted coffee" for your store.

"People who get into roasting for the wrong reasons, who get into it and don't learn anything about coffee, they don't put out the quality. And that doesn't just hurt them," Diedrich says, "that hurts everybody in the industry. I don't want to see that."

To receive training for the Diedrich roasters, you have two choices. You can go to the Diedrich manufacturing facilities located in idyllic Sandpoint, Idaho, at the northwestern edge of the Bitterroot Mountain Range, close to the Canadian border. Or you can (for an additional charge) have Diedrich come to you. For many, the choice is obvious. "We really worried about how the training would work when we moved out here from Orange County, California [near Los Angeles]. We wondered if anybody would come out here. It's not the most accessible place in the world. But believe it or not, we have many more people coming out here to see us than we ever did in super-accessible Orange County. People want to come here because its so beautiful. It's like a vacation."

What to Do?

If you're looking for an in-store roaster, the Diedrich IR series should be somewhere near the top of your prospects, especially if you're new to roasting. There are criticisms about the Diedrich roasters, but every attempt to verify them has led nowhere. Either the criticisms were from second-hand sources, or based on an older, different machine, or on one that was never maintained (obviously if you don't maintain any machine that has moving parts you're going to have problems). It seems that once someone spends upwards of $15,000 on a piece of equipment, they truly believe (like car owners) that theirs is the best.

One criticism that is often heard about the Diedrich is that if you want a dark roast, it's hard to get one without roasting for 25 minutes, drying the beans out. Talking with users of the Diedrich roasters, though, gives the impression that the criticism is baseless. "That's not true. Just this morning, I did three batches of French Roast," said Dick Healy of Sherman Oaks, California's The Coffee Roaster. "Each one in 12 minutes."

The best thing to do is to check out the roasters for yourself and test them for performance, matching exactly how you would want to use them. If you like a dark roast, run a dark roast and see if you get the result you want.

The Diedrich IR series of roasters has some very positive features that are definitely verifiable. It was designed specifically for easy in-store use. It's simple to use, yet manual enough to give control and flexibility. Its parts are all reachable and the machine is easy to clean and maintain. It's relatively compact - the IR-7 takes up just under 9 1/2 of floor space including the cooling bin (which, like most roasters, hangs over the base unit a bit), the IR-12 takes up 11 and the IR-24 takes up just under 18 Sq. ft. The chaff collection system is internal so no extra space is needed for a cyclone.

And it looks good. The IR Series is finished in a powder-coated enamel available in 150 colors. It can also be customized with your company logo. Michael Mitzelfeld says his Diedrich roaster gets comments on its beauty all day long. We should all be so attractive.

The infrared burners, once you understand them, are a good set up for the small batch roaster offering great flexibility and control. If you want to roast larger quantities for wholesale or other applications, you'll want to look at other machines with more power and more conventional heating sources to match a larger mass of beans. Diedrich also has a series of larger roasters for that purpose: the C series in 40 and 80 kilo sizes. These do utilize atmospheric burners for straight on convection heat rather than the Infrared/Heat Exchanger combination. But with a combustion output that produces only 10% of the NOX (oxides of nitrogen) and only 75% of the carbon monoxide and carbon dioxide gases that any other heating system puts out, the infrared system has a meaningful advantage over the more conventional atmospheric gas burners. It also uses an average of 50% less natural gas or propane to run than other roasters. And if energy is a concern of yours, keep in mind that with the IR series roasters the heat exchangers hold on to and use their heat very well, keeping the external temperature of the machine very low. It will feel hot to the touch, but won't burn you. This is good not only for your summer air conditioning costs, but will also keep you a little cooler as you monitor your roasts.

All in all, it's worth looking into. If you need something even smaller than the IR-7, Diedrich has a 2 kilo, tabletop version that the company will debut at the SCAA show in New Orleans.

The Diedrich IR series roaster is definitely not your father's Diedrich. It's a much improved version and a good solid machine. Many describe it as an ideal first or entry level roaster. It's a manual machine, like a stick operated rather than an automatic car, but those who are really into coffee wouldn't have it any other way. As with anything, though, test drive it before you buy it, to make sure it's right for you.
COPYRIGHT 1997 Lockwood Trade Journal Co., Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1997 Gale, Cengage Learning. All rights reserved.

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Title Annotation:coffee roasting equipment
Author:Peel, Carl
Publication:Tea & Coffee Trade Journal
Date:Mar 1, 1997
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