MCR 30kg vs Diedrich DR25 coffee roaster?

Although I have a great deal of familiarity with the Diedrich’s IR and CR series roasters, I was unfamiliar enough with the DR model that I was forced to review Diedrich’s website and study the specs.

This is my answer:

The DR–25 is a much smaller, much lighter built and less powerful machine than my 30kg.

The DR is single phase and all of the motors are sized significantly smaller. Ours are all N-Frame 3-phase. Our cooling tray will accommodate 3 full batch sizes for mixing. Our loader is included with both a scale and a filtration system. Our blowers are high pressure centrifugal, not low pressure squirrel cages. This is important for your roaster because it gives you headroom to maintain exactly the same airflow as your blower or venting become crudded up. You’ll use the drum pressure gauge to correlate fan speed with drum pressure to precisely repeatable airflow setting and RoastPATH will record every change you make on setting for each and every batch.

Speaking of RoastPATH, we’re glad to see Diedrich is finally caught on to offering variable drum and fan speed and some limited version of integrated data logging, but we’ve done that on literally every model as standard from the very beginning. Our 30kg has 15 sensors and readouts that both drive the operator assist functions like automated cooling and automated between batch recovery protocol, but also transmit via a plug and play USB connection to RoastPATH. RoastPATH records every setting change and outcome an operator makes over the course of a roast and then makes that information available for roast review and roast replay functions. These features are standard on every single digitally controlled MCR roaster from 2kg to 60kg.

Ours are the most sophisticated single pass roasters ever built and they’ve set a new standard for roast accuracy and precision. As a matter of cooling performance, none of these guys have figured out how to read a blower pressure curve. That squirrel cage design outputs an enormous volume of air on paper, but in the cooling tray when all the holes are covered by coffee about 70% of that airflow evaporates. Most customers transitioning to a large MCR machine experience an immediate .5 to .75 point improvement in roast quality due to cooling performance alone.

On top of all that, across our entire range of roasters and relative to our competitors similarly sized machines, our drums are significantly larger, thicker, heavier and double walled. At 16″ water column, we’re generating 200000+ BTU’s and the machine is designed to allow you to make full use of all of that heat without automatically inducing heat defect.

If you want a big hulking brute of a high performance machine, we win hands down.

Diedrich is a good company and they build nice stuff. You’ll not go wrong with either machine. Their brochure claims 12.5 to 25 kg capacity. If you have the space and you install it right, my 30kg will produce optimally roast profiled and data logged coffee from between 6kg and 36kg.

We can do this because we have much better better thermometry and feedback loops for gas and airflow and consequently much tighter control over our application of heat plus the headroom in capacity, heat, roast air and cooling capability to make it work.

When our 30kg roaster is installed to spec, and because we designed and certified ALL of our gas trains custom for specialty coffee roasting, you’ll have enormously tighter micro-step gas control and micro-step control between 1 and zero on the gauge. The IR burner in the IR and DR models requires a minimum gas pressure to function that forces the operator to only a low or off gas setting. A lot of the time this means you’re guessing about your finish time and temp because you are forced to coast to the end of your roast.

Incidentally, and as someone that has actually run a bunch of roasters trying to get a better thing out of the cooling tray, from the specs I very much doubt the CR is doing a high quality specialty light roast Ethio at any capacity greater than about 40-45lbs. You would, seriously, be better off running my 20kg at 24kg (48 lbs).

If you get the installation right and if you have the chops or you care to put in the effort to develop the chops, you will get 44% more coffee out of the 30kg.

That’s something along the lines an optimistically charitable 55lbs of green in per batch vs 79.2lbs of green per batch.

One last thing: I haven’t cupped with you and I haven’t cupped your coffee. What the CR will do is run a full batch at something like 50lbs over a 15-17 minute roast to a highly consistent medium dark roast profile with an okay coffee. If you’re running a darker roasted, highly soluble, slightly lower quality coffee for supermarkets or restaurants or bakeries, the CR is a relatively compact solution.

If you’re searching high and low for the next great lot of whatever and you’re busting you a– every day to get a better version of that coffee into bunch of bags, you really want to know me.

I very sincerely wish you the best of success whatever you do it with.

Steve Green

President, Mill City Roasters