Why is my first batch of the day different?

The roaster has not reached thermal equilibrium. Warm up longer, use a consistent between-batch protocol and consider a seasoning batch.

How many batches can I roast per hour?

Typically three to four on a conventional drum roaster, depending on profile length and cooling. Measure your own cycle time.

Batch scheduling: the order you roast in matters

The first batch of the day, the gap between batches and the order of coffees all change how a roast turns out. A practical approach to sequencing a roast day for consistency and throughput.

6 min read Updated 9 October 2026

A drum roaster stores heat in its drum, its air path and its body. The first batch of a cold morning behaves differently from the fifth batch, and a roaster that has been running dark roasts all morning gives a light roast a different start. Scheduling keeps those differences small and predictable.

Warm-up and the first batch

Warm the roaster for long enough that the drum and body reach a stable temperature, then often run a sacrificial or seasoning batch, or put a forgiving coffee first. Record the warm-up in the batch log so the first real batch can be compared with others.

A between-batch protocol

Consistency across a day comes from returning the roaster to the same state before each charge: the same charge temperature, the same idle time and the same airflow setting. Write it down and follow it. Many roasters use a fixed number of minutes at a set temperature between batches.

Sequencing a roast day

Principle	Why
Group by coffee	Fewer changeovers and comparable batches back to back.
Light before dark	Dark roasts leave more oils and smoke in the system; lighter coffees after them pick up less.
Decaf at a set point	Decaf behaves differently and should not be mixed in a cooling tray with regular coffee; clean before and after.
Flavoured coffee last, if at all	Flavourings can carry over; use separate equipment and clean thoroughly.
Sample roasts at the end	They need a different setup and should not disturb production rhythm.

Batch size and throughput

Roasters perform best within a range of their rated capacity. Very small charges in a large drum are hard to control; overfilling slows the roast and cooling. Many roasters work at roughly 50% to 90% of nameplate capacity. A batch cycle of roughly 12 to 16 minutes including charge and drop is common, so three to four batches an hour is a practical planning figure. Measure your own.

Worked example

Roasted output per hour at four batches, by charge size

5 kg roaster at 4 kg charge13.6 kg
12 kg roaster at 10 kg charge34.0 kg
15 kg roaster at 12 kg charge40.8 kg
30 kg roaster at 25 kg charge85.0 kg

Arithmetic example assuming four batches an hour and 15% roast loss. Real throughput depends on your machine, coffee and profile.

End of the day

Close-down

Empty and clean the chaff collector
Record the last batch and any faults
Cool the roaster down following the maker's procedure before switching off fans
Check the plan for tomorrow and green weighed out where possible

Where Roastnet helps

Questions roasters ask

Why is my first batch of the day different?: The roaster has not reached thermal equilibrium. Warm up longer, use a consistent between-batch protocol and consider a seasoning batch.
How many batches can I roast per hour?: Typically three to four on a conventional drum roaster, depending on profile length and cooling. Measure your own cycle time.