The Roaster Desk

By Kai Nakamura · Production roaster & equipment editor · Updated 2026-09-17

Mill City 15kg vs Diedrich IR-12

Production throughput under real utility constraints

→ Mill City 15kg

Mill City 15kg wins on installed cost — confirm Diedrich dealer support in your region before ruling it out.

Capital outlay: WinnerHourly throughput: WinnerAutomation depth: Close
Lowest street price → Mill City RoastersFaster batches → Mill City RoastersIR radiant profile → Diedrich drum physics

Also searched: diedrich ir-12 vs mill city 15kg

Decision picker

What is your primary constraint?
Batch size you roast most often?
Is gas already permitted on-site?

Specification matrix

Batch capacity

Mill

15 kg

Diedrich

12 kg

Heat source

Mill

450,000 BTU/h gas

Diedrich

400,000 BTU/h gas

Drum / chamber

Mill

Carbon steel drum

Diedrich

Double-wall IR drum

Batch time (typical)

Mill

14 min

Diedrich

14 min

Throughput (modelled)

Mill

50 kg/h

Diedrich

40 kg/h

Street price band

Mill

$55,000 USD

Diedrich

$95,000 USD

Exhaust

Mill

950 CFM

Diedrich

900 CFM

Lead time

Mill

12 wks — confirm with dealer

Diedrich

16 wks — confirm with dealer

Automation

Mill

Optional Cropster bridge

Diedrich

IR control panel

Service hub

Mill

USA

Diedrich

USA
Airflow ctrlThermal stab.Drum speedAutomationCapex value
15kgIR-12

Qualitative scores — verify against your roast program

Why this split

Mill City 15kg leads on the weighted score for most boutiques we modelled.

Diedrich stays competitive when infrared precision outweighs the price gap.

Airflow path through a commercial drum roaster from burner to cyclone
Typical drum roaster airflow: burner → drum → cyclone chaff collector

Deep dives

IR radiant heat transfer

Diedrich IR drums radiate through a double-wall — different first-crack timing than convection.

Operators switching from Probat or Giesen need 15–20 calibration batches, not a copied profile.

  • Log development time ratio across 3 charge weights
  • Compare ground colour at same end temp
What to verify with your dealer

Neither OEM publishes binding street prices — quotes move with queue and freight.

Verify with vendor

  • • Confirm Mill City 15kg lead time and freight to your dock
  • • Confirm Diedrich IR-12 install kit and probe package included
  • • Ask for three references at similar elevation and batch size

Side-by-side

Mill City Roasters strengths & gaps

  • Mid-tier production capacity
  • Competitive pricing
  • Higher gas use than Loring

Diedrich strengths & gaps

  • Infrared precision
  • Strong US service network
  • Higher gas consumption vs Loring

FAQ

Looking for diedrich ir-12 vs mill city 15kg?
Same comparison — Mill City 15kg is listed first by convention. Verdict and spec matrix are identical either way.
What throughput can I expect?
Modelled: 50 kg/h (Mill City 15kg) vs 40 kg/h (Diedrich IR-12) including a 4-minute charge/cool cycle.
What street price should I budget?
Mill City 15kg: $55,000 USD (As quoted Q1 2026, US factory). Diedrich IR-12: $95,000 USD (As quoted Q1 2026, ex-install). Request refreshed quotes — neither includes install.
Which supports Cropster logging?
Mill City 15kg: Yes with RT bridge — confirm with dealer. Diedrich IR-12: Yes with RT bridge — confirm with dealer.

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