Mastering Your Roaster Warm-Up and Cool-Down: A Step-by-Step Guide

Whether you're new to coffee roasting or just looking for additional guidance, one of the most essential (and often overlooked) steps is properly managing the roaster warm-up and cool-down process. These procedures are critical—not only for protecting your equipment but also for maintaining roast consistency and reducing the risk of fires and other hazards in your roasting space.

Below, we’ve outlined the warm-up and cool-down steps we use for our Mill City MCR-15 drum roaster. These principles can be adapted for many drum roasters with similar configurations.

🔥 Roaster Warm-Up Procedure

1. Inspect the Roaster

Before powering on your roaster, perform a quick inspection:

• ✅ Check the cyclone or chaff canister for leftover chaff and clean out if needed (dirty chaff containers are a common cause of roaster fires).

• ✅ Inspect the gap between the drum and shell to ensure it’s set to manufacturer specs.

• ✅ Confirm the cooling tray is empty and has unobstructed airflow. Use a brush or vacuum if needed.

2. Power On & Connect Your Computer

• Switch on the roaster’s main power and fan.

• Connect your computer and load your roasting software (we use Mill City's RoastPATH).

• Make sure the software is receiving accurate data from the roaster.

3. Set Initial Heat and Airflow

• Open the gas line and ignite the burner.

• Gradually introduce heat—start at around 30% gas pressure to avoid warping the drum.

• Set the fan to moderate speed (~50%) to help cycle heat evenly.

4. Heat Soak and Stabilize

• Allow the roaster to warm up to your initial charge temperature (usually takes 20–30 minutes).

• Increase gas to about 60% max capacity and slightly increase airflow.

• Let the roaster cycle at charge temp for an additional ~20 minutes.

5. Check Temperatures & Begin Roasting

• Verify drum, environmental, and bean probe temperatures.

• Once the drum has stabilized at the desired charge temp, and everything reads normally, charge your beans and begin roasting!

❄️ Roaster Cool-Down Procedure (After Your Final Roast)

1. Begin Cooling the Drum Gradually

• Turn off ignition and close the gas line.

• Let the drum cool down slowly to avoid metal warping.

• Track the cooldown process (we log it in RoastPATH as a "cooldown roast").

2. Flush With Airflow

• Set airflow to moderate (~50%) to remove residual smoke and heat.

• Gradually increase airflow as the roaster cools down further.

• This helps reduce the buildup of chaff, dust, and oils, which can be fire hazards.

3. Power Down Safely

• Once the drum and environment temps drop below 130°F (54°C)—typically after 60–90 minutes—shut down all fans and electronics.

🧼 Post-Roast Cleaning Routine

To maintain safe and consistent performance, clean your roaster after every roast session:

• Remove chaff and debris from the cyclone, burner shelf, cooling tray, and drum.

• Ensure gas lines are closed and all power sources are disconnected.

Final Thoughts: Warm-Up and Cool-Down Matter

Taking the time to properly warm up and cool down your coffee roaster will:

• Prevent thermal shock to components

• Promote even and consistent roasts

• Reduce the risk of fires or mechanical damage

• Extend the lifespan of your roasting equipment

Larger drum roasters may take longer to reach full heat soak and to cool down safely, while smaller roasters will complete both stages more quickly. No matter your machine, these principles apply across the board.

Hope this helps, and happy roasting!