Looking to Buy a New Roasting Machine? This One Mistake Could Put You in Danger

Dirty exhaust systems are the most common cause of roaster fires.  Protect your machine, your business, and yourself by installing the proper ducting and ventilation.

Here’s a scenario no coffee roasting professional wants to think about…

You work hard to pursue your passion and start your own roasting company.  Money is tight, so you’ve been frugal where you can, and you’ve managed to bootstrap a sustainable business.

Unfortunately, the hidden costs of ducting and ventilation on your machine snuck up on you.  You simply installed what you could afford as a result.  Maybe it was a standard heat exhaust system like what you would use for a fireplace, something you rigged from the hardware store, or a lower-grade commercial system.

The thing is, coffee roasting operates with a different kind of pressure—something you might not have known.  That means that the ventilation you installed wasn’t enough to keep everything clean and safe.  Your machine catches fire, part of the building may have been damaged, and you’re lucky that no one on your team got hurt.

This story might seem far-fetched at first, but Diedrich alone receives two or three reports of roaster fires per year on average.  After inspection, we find that a dirty exhaust system is the leading cause.

How dirty is the roasting process?

The entire roasting process is dirtier than you think.  Every roast discharges oil, chaff, and dust that forms a residue.  As that residue cools, it condenses on the internal walls of airflow passages, blowers, chaff collection systems, and the roaster exhaust duct.

We know that the heat environment inside of a roasting chamber is created by a balance of convective, conductive, and radiant heat.  A dirty machine changes that heat balance by diminishing the air responsible for it.

The accumulation of residue inside the machine reduces airflow, which means that, all else being equal, you’ll begin to fall behind on your roasting profile.  To stay on profile, you might turn up the gas (which is conductive heat) to make up for the lack of convective heat.

This adjustment dramatically changes the roasting medium, which changes the heat transfer rate, which changes how the chemistry evolves, which finally alters the flavor profile of the coffee.  When one of the primary goals of any roaster is consistency, that can have disastrous results for your business.

What are the dangers of a dirty roaster?

There’s more at stake than just your flavor profiles.  Residue buildup is highly flammable, putting both your equipment and your staff at risk.

With over 6,500 roasting machines installed worldwide, Diedrich receives about two to three fire reports annually.  Even when the main parts of the roaster are kept impeccably clean, a dirty exhaust system can still cause a chaff or duct fire.

Methane gas, a byproduct of heating the coffee during roasting, isn’t efficiently removed from the heat environment when there’s too much residue.  The vent pipes are supposed to dissipate heat into the outside air.  However, as residue builds up internally, it actually acts as an insulator.

The result is increasing, uncontrolled temperatures.  As more chaff blows out of the roasting drum with the pressure created by carbon dioxide, it becomes fuel for a fire.  The more “fuel” (oil & chaff) there is when a fire does happen, the hotter and longer the fire will burn and the more damage it will end up causing.

How can I protect myself and my business?

The single most important thing you can do as a roaster is to keep every part of your system clean.  Most manufacturers provide general guidelines for cleaning their machines, but they are difficult to specify exactly as the proper procedures can vary depending on the particular installation, geographical climate, roasting styles, and other factors.

For example, a moist and humid climate will require more frequent cleaning, especially if it’s cold (which results in more condensation).  Similarly, a machine that handles a lot of dark roasts should be cleaned more often as the exhaust smoke carries more oils than in lighter roasts.

Many roasters neglect their ventilation systems, even though this is the most important part.

Ventilation comes in many forms: open air, direct venting, a powered hood, or other custom options.  When considering the best ventilation option for you, it’s important to remember that coffee roasting is a positive pressure system rather than a negative pressure system.

That means that, instead of heated air rising so that pressure in the pipe is less than pressure in the room, roasting waste causes pressure in the pipe to be greater than that in the normal atmosphere.

Anything like stovepipes, fireplace venting, or hardware store solutions will not work unless each individual joint is sealed.  Even then, it makes cleaning exponentially more difficult and thus less frequent, and it offers no real protection against a potential fire’s high temperatures.

Diedrich recommends installing UL certified, Class-A, double-walled, positive-pressure ducting.  In most states in the U.S., it must be installed by a professional company such as VentConnection.com

While these systems might seem expensive up-front, the fact that they keep your machine clean, your staff and customers safe, and your company running smoothly completely justifies the price.  Whether you’re looking for a new machine or hoping to update an existing one, this isn’t something to consider.  Protecting yourself is something you need to do.

Keeping you and your team safe during the roasting process should be your first priority.  Luckily, it’s ours, too.  Ducting, Venting

Diedrich Roaster Maintenance and Service: Here’s What You Need to Know Before You Buy

Your roasting machine is an investment — a big one.  And for a lot of us, it’s the lifeblood of our business.

That’s why when you’re deciding what kind of roaster to buy, you need to consider all the future costs up front.

Down the road, what kind of big maintenance are you going to have to do?  How much regular maintenance is your machine going to require?  Will it be possible to upgrade in the future?  If something unlucky happens, how easy and quick will it be to fix?

We can’t answer these questions for other companies.  But speaking for ourselves, we’re committed to perfecting both the science and art of roasting — down to the technical components of every machine.

So if you’re hunting for a new machine and curious about what having a Diedrich roaster is like, here are a few things you should know.

Our entire machine is built to last

Commercial roasting machines, no matter how big or small, have a lot of parts.  Screws, belts, ducts, chains, vents, wires… you get the picture.

It’s one thing to ask how long a machine will last.  But with a machine as complex as a coffee roaster, you have to ask how long each individual part will last as well.

Will it cost more in the long run to buy a cheap machine whose parts you’ll have to replace frequently?  Or would it be wiser to invest in a high-quality machine from the start?  The answer depends on you and your business, but Diedrich machines favor the latter approach.

Some roasting machines have belts, chains, or even roasting drums that break down and need to be replaced. This is part of the “expected maintenance” you have to factor into your purchasing decision.

Our drums, however, are hand rolled mild steel with welded fins and return paddles that never need to be replaced, and we truly build the entire roaster the same to last.

Simple upkeep and cleaning will keep it running forever

How can you make sure that you’re maximizing the lifespan of your roasting machine?  The biggest thing you can do is to simply keep it clean.

We really can’t stress enough how important keeping your machine clean is.  It’s not just a matter of quality; it’s a matter of safety.

Diedrich alone receives two or three reports of roaster fires per year, the leading cause –not doing proper maintenance.  Protect yourself, your team, and your business by frequently inspecting each part of your roaster and following the Diedrich cleaning guidelines.

We recommend simple upkeep like greasing bearings and staying on top of regular cleaning.  Taking just a few minutes at the end of each day or week can help keep everything running smoothly and guarantee a long-lasting machine.

You don’t have to wait months for replacement parts

Have you ever ordered something online only to practically forget about it by the time it shows up at your door weeks later?

If that happens with a pair of shoes, okay.  But if it happens to your business, your daily production could seriously slow down or temporarily stop altogether.

Imagine the loss of revenue — or at least the massive inconvenience — it could cause your business if you needed a replacement part but had to wait forever to get it.

That’s exactly what we want to avoid.

Everything we build is manufactured in the Sandpoint Idaho in the United States, so there’s no long wait times for parts if they ever need replaced.

With other companies, waiting for the right part could take months.  But with Diedrich, you can rest assured that your roaster will be back up and running in no time.


Tech Support

With Diedrich you get unlimited FREE tech support, we don’t charge you like the other guys or don’t return your calls we have a team of 6 tech support technicians/agents with a combined 50 years of experience with Diedrich.  There is not a question they can’t answer or figure out for you. We service customers world wide and are constantly updating ways for you to contact us quicker if needed.


Why is UL Certification Important for Coffee Roasters?

Roasting can be a lot of fun, especially when you get to see the way people smile after taking a sip of their favorite brew.  The whole process is creative and artistic, and, as any other roaster will tell you, we do it because we love it.

Like every business, however, roasting companies have to deal with legal requirements, maintenance, and all of those less-fun things that enable us to be responsible and successful business owners.

One major concern for any business is safety.  Taking proper safety measures not only prevents possible litigation to your business, but most importantly, it keeps your staff and equipment out of harm’s way.

Here’s an easy way to know whether your tools and other equipment are the safest options: Check to see if they are UL certified. (Hint: they should be!)

What is UL anyway?

You might recognize the “UL” stamp on a few of your products, but what does it mean?

UL stands for “Underwriters Laboratories,” which is an organization that verifies the safety and quality of manufactured products.  Simply put, UL-certified products have been thoroughly tested to meet rigorous safety standards.

UL is the leading nationally recognized testing authority in the United States (along with companies like the FCC and CSA).  They list over 1,000 standards for categories ranging from wire size and current capacity to life safety and more.

While mostly related to electrical and fire safety, UL has also developed standards for things like environmental sustainability and food and water quality.

The process of certifying a product is simple.  First, manufacturers submit their product for UL testing.  Then, if the product passes, it gets stamped with an official UL mark.

Submission is not legally required, per se, but most manufacturers have incentive to go through the process anyway.  The National Electric Code requires the use of UL-verified products when available, and the stamp itself is a distinctive mark of safety and quality.  When consumers see a UL stamp, they know that the product is safe and effective and can be professionally installed. If they don’t you will have to go through a „field inspection” which can be very costly.

Listed, recognized, or classified?

Though you might recognize one UL logo or a single UL stamp, there isn’t just one “general” UL mark.  A product’s “marked” status is actually split into three categories: listed, recognized, and classified.

If a product is UL listed, it doesn’t necessarily mean that it was tested by UL itself.

Instead, UL verifies that the manufacturer is able to make products which fulfill its standard safety requirements and minimize known risk to the user.  The manufacturing company can test and apply the label themselves, though UL will follow-up with them regularly.

Products that are UL recognized are always components for larger products.  In a roasting machine, these are things like the motors, valves, and circuit boards.  And just like the UL listing service, manufacturers are authorized to test and stamp the products themselves.

UL classified products can actually receive a variety of marks.  Classification service is used to evaluate one or more of the following:

  • Specific risks such as fire or electric shock
  • Performance under certain conditions like temperature and water exposure
  • Regulatory codes
  • Other standards, including international codes
  • Miscellaneous conditions generally desired by UL

So, what’s the difference between UL and CE?

We’ve talked a lot here about UL because that’s what’s required and you will see in the United States.  Similar testing companies exist in other countries around the globe.

In Europe, they have the CE certification.  This means that they have also passed health, safety, and environmental regulations set by the European Union.  Products with a CE mark can circulate freely among countries in the EU, and products covered by the “New Approach” requirements must have the mark.

If an item doesn’t have a UL stamp in the United States, there might be cause for concern.  It’s possible that it wouldn’t pass a safety standards test even if it were submitted for verification.  In any case, it can be difficult to know whether using that product will increase risk to your business or put people in danger.

When a UL product is available, it’s best to choose that one instead.

Lucky for you Diedrich is fully UL compliant in the United States and CE compliant in Europe and other countries.

With Diedrich you will not have any problems passing your local inspections.


Is Your Café Getting Left Behind in the Cold Brew Trend?


Is your café selling cold brew?  If not, you’re missing out on a ton of demand and revenue.


According to research group StudyLogic, reported in Bloomberg, sales of cold brew alone increased 80% from February 2016 to February 2017 while traditional coffee beverages increased by only 1.5%.  Fortune cites Mintel’s estimate that the trend grew by nearly 340% from 2010 to 2015.


Along with ready-to-drink products, the cold brew market is worth nearly $2 billion in the U.S.  That’s not to mention how it significantly impacts other markets.


Because cold brew takes two to three times more beans to produce than other brewing methods, the cold brew trend could reinvigorate that market as well.  Coupled with bottling and distribution, it has a significant multiplier effect throughout the industry.


Cold brew is an exploding market, and your coffee shop needs to be carrying it.  Below we’ll outline what makes cold brew attractive to producers and consumers and what equipment your café will need to hop on the trend.


A Primer on Cold Brew



Two of the most important variables of any brewing method are water temperature and extraction time.  Cold brew is steeped in cool water for anywhere from 12 to 20 hours, trading less heat for more time.


An evolution of iced coffee, the cold brew method started in New Orleans and the south and quickly spread thanks to several major companies like Stumptown and even Starbucks.  In fact, the “New Orleans style” cold brew, known for its distinctive chicory flavor, is now being sold by brands like Blue Bottle all across the country.


Nitro cold brew, or “NCB” for short, particularly has its advantages over iced coffee and even more traditional pour-over and espresso methods.  Because the coffee is infused with nitrogen and isn’t exposed to oxygen, a batch can stay fresh for weeks.  This stability makes it easy to package as well, which explains all the bottles you see in grocery stores and café refrigerators these days.


And if your café often experiences high demand and wait times, cold brew can be a great solution.  When offered on tap, a customer on the way to work can be in and out in a matter of seconds.  Just pour and go.


From a consumer perspective, the taste and feel of nitro cold brew is perfect for those warm, sunny days.  Since it doesn’t use high temperatures which typically extract oils from the coffee, cold brew contains significantly less acidity.  The result is a super smooth, well-rounded drink that tastes sweet without the addition of any sugar.


Contrast this to a more traditional cup of iced coffee, which is essentially hot coffee decanted over ice.  The hot coffee itself showcases a certain amount of acidity, but the balance can quickly change — often harshly — as the beverage cools and the ice begins to melt and dilute it.


Some coffee purists lament the loss of brightness from the lack of acidity in cold brew, which is exactly what makes many varieties of coffee stand apart from the rest.  But for those who want the rich and creamy feel of a milkshake on a hot summer’s day, cold brew seems like the perfect way to hit the spot.


What do you need to start selling cold brew?



Serving cold brew is relatively simple once you have the right equipment and get a hang of the labor process.  One of the most popular ways to offer it is from a keg and tap.


Here’s a list of what you’ll need:


  • Keg + “kegerator” (keg refrigerator)
  • System for making cold brew
  • Nitrogen regulator
  • Nitrogen supply

There are essentially two ways to serve cold brew on tap.  The first is “still,” which pours more like coffee and cream.  It uses low pressure, so your nitrogen tank can last quite a long time.


The second and more popular way is “infused,” which pours like a Guinness with a fat cap of stout on top.  For this method, you’ll also need a stout faucet and a nitro keg lid.


The hardest part is getting the equipment set up and coming up with a unique and unforgettable cold brew recipe.  But once those two things are taken care of, you will be well on your way to reaping one of the most exciting trends to ever hit the coffee industry.


What has been your experience with serving cold brew, and how has it impacted your overall sales?  We’d love to hear from you.


A question I get frequently is, “What is infrared?” The impression is that it is something like Ming the Merciless’ Death Ray! One “roaster” ordered me to accept that a Diedrich Roaster roasts beans from the inside-out. I was sharing a cab with him at the time and it was a little scary, so I didn’t try to change his mind. If someone tries to tell you this, watch out.

Although “roasting” from the inside out is physically impossible with radiant heat and would be a really crappy way to roast anyway, it does bring out the concern that infrared heat sounds scary and dangerous; ultra-secret scientific woowoo. So, bwahahahaha weak earth creatures, prepare to meet your doom!

“That is nonsense,” you say. What is it really? We use gas, just like, well … everyone, only we contain the flame into a long box, which is as wide as the drum. The top of the box is closed with ceramic tile. This tile is superheated by the gas flame in the box and gets so hot, the heat radiating off the tiles is invisible; it is radiating in the infrared spectrum. No blue and yellow flames here! (Full of contaminants) Invisible waves of infrared light waves surround the drum and heat exchangers. When they hit the metal, they heat the metal in a complicated atomic rave. The rest is roasting coffee.

The thing that is different about our burners compared to all the blue flame roasters is that when you look inside our roaster you see the pure wide rectangles of brilliant orange/red tiles extending the entire length of the drum. Consistent, clean, dependable heat directly transferring to the drum and heat exchangers. Almost all of the combustion is taking place behind those beautiful ceramic tiles. Our infrared burners produce an even band of heat that assures there are no “hot spots” or cool temperature bands that can screw up your roast.

This is just like the ceramic top stove-tops many of us have at home – fast, dependable, controllable, and very powerful.

So don’t worry about infrared! It is completely safe, even to weak earth creatures. And, when it comes to roasting coffee, it is the best … period.



[email protected]


Could we be more confusing? What is the difference between an IR roaster and a CR roaster? I can’t count the number of times I have been asked this.

This is a classic example of “Why do we do that?” Diedrich has been building roasters for 40 years and over time we have grown, innovated, and improved. A Diedrich roaster today is a lot more sophisticated than the ones first built in Steve’s dad’s garage. So the reason we named the roasters IR and CR is a little lost in history.

As far as I can tell, Steve knew he wanted to use infrared burners on his specialty coffee roasters. He knew that they used less gas to produce the same BTU’s and produced a clean heat evenly across the drum. He also knew that using less gas meant he produced far fewer dangerous chemicals that would get drawn through the beans. Steve was all about producing the cleanest and freshest cup possible and that discipline drives our designs today.

Then along came a customer who wanted a BIG roaster. Steve wasn’t so sure he could source infrared burners that would produce enough BTU’s to support a big load of coffee so he built his first CRs (Commercial Roaster) with an atmospheric burner. The same flame throwers that are in our competitors’ roasters.

Through testing however, Steve discovered that he was wrong! He discovered that he could design larger burners that produced a lot more BTU’s using a lot less gas. Soon all of our roasters, big and small, used infrared burners.

The legacy of this though is that our 1 through 12 kilo roasters are called IR (infrared) and the 25 through 280k roasters are called CR (commercial). But they are all infrared!
This has produced a lot of confusion and rumors out there. To make in worse for the past couple of years we started calling IRs “In-Store Roasters” which doesn’t come close to describing all the ways folks use the IRs.

So to clear things up…

All our roasters use infrared technology to roast coffee
Infrared is the cleanest and most fuel efficient source of roasting heat, period!
Infrared at full gas far exceeds the full BTU output of comparable flamethrower roasters
Reduced combustion gases in the drum produce a cleaner cup
I personally would like to give our roasters real names; I think the IR-5 should be called Charlie. I suppose it is a good thing that it isn’t up to me.



[email protected]

The Essentials of Coffee Roasting : Have a good Plan

I have been asked several times, “What is the single most important piece of advice you would give a new roaster?” The answer is easy but the practice may not be: always have a plan before you start roasting.

On the surface this seems easy enough.

Your plan, however, should be more than, “make green into brown.” It should involve having a purpose for your roast and an expected result.
An example might be: Roast 5 ARRIVAL samples to a cupping standard for evaluation tomorrow morning. Now you know what you are roasting, why you are doing it and an expected outcome of Agtron 58 whole bean of 58 +/- 1 in 8-12 minutes. This is a simple, well thought out example.

Others plans might be a little more complicated. Here are some plans you might want to consider. You can take these as a starting point for your roasting and make them as detailed as you want.

If you have been roasting for a while you probably have a set of ‘common’ profiles you use. If not, build some thereby creating a small library of starting profiles. This will save many hours and lots of coffee in the future while making your outcomes more precise and consistent.

A good plan well executed saves time, money, and frustration while increasing quality and consistency.

Rocky Rhodes