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Bean lock might not happen with one origin, and start happening with a different origin. This is because density and size of the beans affects bean lock. The amount of chaff in the chaff collector also affects airflow: failure to empty the chaff collector between roasts may cause bean lock.
The different types of bean lock happen at different stages in the roast:
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When beans lock after 160°C/320°F this is known as late bean lock. The roaster is will normally detect late bean lock as thermal runaway, and stop the roast with the message: “Thermal runaway, press ⏵ to cool”.
Wild upward fluctuations in the temperature line will be apparent in the roast log prior to the roaster terminating the roast.
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In rare cases thermal runaway will occur when bean lock has given rise to combustion of the bean mass in the roaster. In this case |
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there will be billows of black smoke and, very rarely, flames |
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. If this occurs do not initiate cooling, but immediately turn the roaster off |
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at the wall, unplug it, and if safe to do so, take it outside or use your kitchen fire extinguisher. This is a rare situation, but as with any food cooking, combustion of the food is always a possibility. If this does happen to you, please follow up by contacting Customer Support for further guidance. In most cases after thermal runaway, cooling can be initiated and will complete normally. Then please follow the guidelines at Solutions, below. |
Wild upward fluctuations in the temperature line will be apparent in the roast log prior to the roaster terminating the roast.
4. Cooling bean lock
When beans lock only during cooling, this is known as cooling bean lock. This happens when the fan slows during cooling.
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Calibration: Ensure that your roaster fan speed is calibrated correctly. See Fan speed Bean circulation calibration.
Fan preview: Check circulation before starting a roast with Fan preview. If circulation is too low, correct it before starting the roast.
Reduce quantity of beans: If fan speed is correctly calibrated and beans are circulating correctly at the start of the roast, but you are still experiencing early or late bean lock, the simplest and quickest solution is to reduce the batch size. For example, if you have loaded 120g into the roaster and experience bean lock, try loading 100g or 80g until you are roasting successfully. If you have BOOST do this without changing the entered load setting.
Increase load setting: If you have BOOST, increase the entered batch size. For example, if you have loaded 120g into the roaster and experience early or late bean lock, try entering the load size as 140g or 160g. This will deliver more air to the same amount of beans.
Custom profile: If you are creating your own profile you should consider editing the fan speed profile to deliver more air in the parts of the roast where beans are locking up. See Uneven roasting for more help on editing the fan speed profile. If you are dealing with cooling bean lock deliver more air in the late part of the cooling cycle by increasing the ‘cooldown lo speed’ setting in the profile.
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