Probat vs Diedrich: Which Coffee Roaster Fits Your Roastery?

Probat vs Diedrich comes down to two ways of putting heat into a drum. Probat has built gas-fired drum roasters in Emmerich, Germany, since 1868. Diedrich has built infrared drum roasters in Ponderay, Idaho, since 1980. Both make excellent coffee. Both hold their value on the used market. The right pick depends on your batch size and roast style. It also depends on how much of the roast you want to steer by hand.

This guide puts the two brands side by side. You'll see how each one heats the beans and which models line up at each batch size. We also cover smoke control and what we see when these roasters come through CoffeeTec.

Probat vs Diedrich: The Short Answer

Pick Probat if you want a classic conductive drum roast and a path to very large batches. Pick Diedrich if you want gentler infrared heat and fine control over small and mid-size batches.

• Probat heats a rotating drum with a gas burner. Beans take heat from the hot drum wall and from moving hot air.
• Diedrich uses infrared burners, so the heat reaching the beans is softer and more indirect than an open flame.
• Both brands meet head-to-head in the 12 kg class: the Probat P12 or L12 against the Diedrich IR-12.
• Probat scales far past 100 kg per batch with its G series and industrial lines. Diedrich's CR series reaches 280 kg.
• Classic Probat models like the L12 and UG series are hands-on machines. Diedrich offers both manual and automatic IR roasters.
• Most commercial installs of either brand need smoke control. Both makers build their own afterburner options.
• On CoffeeTec, the 12 kg class is the busiest size for both brands, on the buying and selling sides.

Probat vs Diedrich at a Glance

The biggest differences are the burner type, the size range, and how each machine feels to run day to day.

See what's in stock today in our used Probat roasters and used Diedrich roasters collections.

Two Companies, Two Roasting Traditions

Probat is the older European drum tradition. Diedrich is the American specialty roaster that grew up alongside the café roasting boom.

Probat

Probat started in Emmerich am Rhein in 1868 and took the Probat name in 1959. Today it builds everything from 1 kg shop roasters to full industrial roasting plants. Its classic machines (the L12, UG15, UG22 and G series) are known for heavy cast iron drums and service lives measured in decades.

The modern P series (P01, P05, P12 and P25) keeps the drum design and adds touchscreen controls, adjustable drum speed and airflow settings. Because so many Probats have been built over so many years, parts and service know-how are easy to find.

Diedrich

Stephan Diedrich founded Diedrich Roasters in 1980, building on his family's long history in coffee. The company moved to North Idaho in the early 1990s and still builds and tests every roaster in the USA.

Its IR roasters became fixtures in specialty cafés and small roasteries, from the 1 kg IR-1 to the IR-12. For production, the CR series runs from 35 kg to 280 kg per batch. Diedrich also makes the newer DR line, including the 3 kg DR-3 and the 25 kg DR-25.

How Each Roaster Heats the Beans

A Probat leans on the hot drum and strong airflow. A Diedrich leans on infrared heat that reaches the beans more gently.

On a Probat, a gas burner heats the rotating drum and the air that moves through it. Beans tumble against hot metal and pick up conductive heat from the drum wall, plus convective heat from the airflow. Thick cast iron on classic models stores a lot of heat. That thermal mass helps explain why Probat owners call the roast stable and easy to repeat once it's dialed in.

Diedrich swaps the open flame for infrared burner panels. The panels radiate heat toward the drum and the air path, so the beans see softer, more even heat with less direct flame contact. Roasters who like Diedrich often point to this as the reason for lower scorching risk and clean, sweet results.

Both are still drum roasters at heart. If you're weighing drum designs against fluid bed and convection machines first, our guide to drum vs air roasters covers the basics.

Roast Character in the Cup

Many roasters who have run both report a lean: Probat for brightness and clarity, Diedrich for sweetness and body.

Probat's conductive drum heat and strong airflow are often credited with lively acidity and clarity. That's one reason the brand shows up so often behind light, fruit-forward specialty roasts. Diedrich's gentler infrared heat often gets credit for rounder, sweeter coffees with more body. That suits chocolate and caramel-driven blends and espresso.

Treat that as a starting point, not a rule. A skilled roaster can pull a bright Ethiopian on a Diedrich and a heavy-bodied Brazil on a Probat. Your green coffee and your profile matter more than the badge on the front panel.

Probat and Diedrich Models Matched by Batch Size

Most buyers aren't choosing between whole brands. They're choosing between two specific machines at the same batch size.

1 kg shop and lab roasters: Probatino or P01 vs Diedrich IR-1

At 1 kg, both brands serve café roasting, training and profile development. The Probatino and P01 bring the Probat drum feel to a countertop-size footprint. The Diedrich IR-1 delivers the same infrared heat as its bigger siblings, making profiles easier to carry up the range later.

2.5 to 5 kg: Probat P05 or L5 vs Diedrich IR-2.5 and IR-5

This is the jump from café roasting to small wholesale. The Diedrich IR-2.5 and IR-5 are among the most common small-batch Diedrichs on the used market. On the Probat side, buyers look at the modern P05 or a classic L5.

The 12 kg workhorse: Probat P12 or L12 vs Diedrich IR-12

This is the matchup most buyers are really asking about. A 12 kg batch can run four or more roasts an hour, enough for a growing roastery with a solid wholesale book.

The Probat L12 is a long-running favorite: simple, mechanical and easy to service. On older L12s, airflow is shared between the drum and the cooling bin, so roasting and cooling happen one after the other. The Probatone and P12 run both at once and add modern controls. The current P12 handles batches from 1 kg up to 15 kg. The Diedrich IR-12 comes in manual (IR-12M) and automatic (IR-12A) versions. Automatic units are a strong fit for small teams that want saved profiles and repeatable batches. A recent CoffeeTec listing paired a 2005 IR-12 with its matching Diedrich loader and destoner, a setup many buyers ask for. Compare live IR-12, L12 and P12 listings in our 12 kg roasters collection.

20 kg and up: Probat P25, UG22 and G series vs Diedrich IR-24 and CR series

Above 20 kg, the two brands spread apart. Probat buyers look at the P25, a vintage UG22, or G series machines from 45 to 120 kg. Diedrich buyers look at older IR-24 units and the CR series, which runs from the CR-35 up to the CR-70, CR-140 and CR-280. If you plan to keep growing on one brand, both offer a path. Probat simply goes further into industrial plant territory.

Smoke Control and Energy Use

Neither brand burns its own smoke inside the roaster, so most commercial sites pair either one with a separate emissions unit.

Many cities and air districts require roasteries to treat exhaust before it leaves the building. Probat builds its own thermal afterburners and emissions systems, and older Probats often come with a matched afterburner. Diedrich makes its own catalytic oxidizer, the DCO. Diedrich says the DCO uses about half the fuel of a conventional thermal afterburner. Real savings depend on your batch count, hours and gas rates.

We see both brands' units come through CoffeeTec as part of roaster packages and on their own. A recent example was a 22 kg Probat UG22 listed with its original Probat afterburner. Another was a standalone Diedrich DCO 7/12N afterburner. If you need to add smoke control to either brand, browse our afterburner solutions.

Want a design that handles smoke inside the roaster itself? That's Loring's approach, covered in our Loring vs Probat comparison.

Controls, Automation and Data Logging

Classic Probats reward a hands-on roaster. Diedrich gives you a clear choice between manual and automatic.

A classic L12 or UG22 is mostly manual. You steer the roast with gas and airflow changes and feel the machine respond. Plenty of roasters prefer it that way. Many owners add thermocouples and data logging so they can track and repeat roasts in Cropster or Artisan. The P series moves those controls to a touchscreen, with adjustable drum speed and airflow.

Diedrich's IR roasters are built for logging from the start. Manual IR models let you control gas and airflow yourself. The automatic A models add saved profiles and automated playback. Both work with Cropster and Artisan.

Maintenance and Long-Term Ownership

Both brands are built to run for decades with routine care. The difference is mostly in what you service.

Probat's longevity is legendary. We still list UG and G series machines from the 1950s and 1960s that are roasting in production. Expect regular cleaning of the drum, chaff collector and exhaust, plus bearing and seal checks on older units.

Diedrich keeps parts available across model generations. That lets IR roasters from the 1990s stay in service with new burners, pilots, gas valves and motors. Before you buy a used one, ask when the burners, pilot assembly and drum bearings were last serviced.

What We See When Probats and Diedrichs Come Through CoffeeTec

Both brands come up often, and the 12 kg class leads for each one.

Our listing and sales records show the pattern clearly. From October 2024 to October 2026, CoffeeTec listed 48 used Diedrich roasters, and 21 were IR-12s. We listed 42 Probat in the same window. The 12 kg L12 and P12 made up the largest group, at 13. On the sales side, 24 Diedrich and 14 Probat roasters sold. The IR-12 led Diedrich sales, and 8 of the 14 Probat sales were L12S or P12S.

The age range is just as telling. Half the Probat sellers we've brought in since 2021 were built before 2004, and the oldest dates to 1950. Diedrichs run newer: half were built in 2015 or later. Both brands keep working long enough to change hands more than once.

Whichever brand you choose, ask the seller for these before you commit:

• Year built, last date in use, and approximate hours or batches roasted
• Service records, including any burner, motor, bearing or control upgrades
• Fuel type and power: gas type, voltage and phase must match your site
• What's included: cyclone or chaff collector, afterburner or DCO, loader, destoner, vent pipe
• For a Probat: drum and bearing condition, and which afterburner setup it ran with
• For a Diedrich: burner and pilot condition, and whether it's a manual or automatic model

Our full guide on how to buy a used coffee roaster walks through inspection, freight and paperwork step by step.

Which One Should You Buy?

Start with your batch size and building, then your preferred roast style.

Pick your batch size, control style, and roast level below to see which Probat and Diedrich models match.

Choose Probat if:

• You want a classic conductive drum roast and hands-on control
• You lean toward bright, high-clarity light roasts
• You may need more than 70 kg per batch as you grow
• You want the widest choice of used sizes and years, from vintage UG drums to modern P series

Choose Diedrich if:

• You want gentle infrared heat and a lower scorching risk
• Your menu leans toward sweet, full-bodied coffees and espresso
• You want a choice between manual and fully automatic versions of the same model
• You roast mostly in the 1 kg to 12 kg range and want profiles that scale across one brand

Still comparing other brands? Our Probat vs Giesen guide covers a drum-to-drum switch. American drum builders like US Roaster Corp are also worth a look next to Diedrich at the same batch sizes.

Selling One to Buy the Other

Many buyers in this comparison already own a roaster, and selling it often funds the next one.

Say you're moving from a Diedrich IR-5 to a Probat P12, or from an L12 to an automatic IR-12. The roaster you're leaving behind has a ready audience. Since 2021, Diedrichs have drawn 132 buyer deals on CoffeeTec and 65 on Probats. The IR-12, IR-5, L12 and P12 lead both lists. Check what yours is likely to bring with our guide on how much your used coffee roaster is worth. Then pull together service records, clear photos and utility specs. Buyers ask for those first.

Find Your Next Roaster, or Sell Your Current One

CoffeeTec has served the coffee industry since 1972. Browse current Probat and Diedrich listings, or ask our team to track down a specific model. Upgrading? List your roaster on CoffeeTec with zero commission and reach buyers already searching for your brand.