Dealing with "heat too fast" error

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kaffelogic
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Dealing with "heat too fast" error

#114

Post by kaffelogic » Wed 05 Jun, 2019 1:49 pm

The Nano 7 is designed for batch sizes of between 90 and 120g green beans. Smaller batches won't roast correctly with the default profile and the machine tries to detect them and alert the user. That is why you sometimes get the "heat too fast" message. It is caused by
  • Less than approx 90 g of green beans in the roaster
  • No beans in the roaster at all, and
  • A batch of roasted beans in the roaster.
However, you can also get this message when you have modified the profile. If you make a change to the initial rate of rise of the profile, you must make a corresponding change to the preheat power setting. That is because preheat power, and preheat power only, controls the first 30 to 40 secs of the roast. After that the curve following commences. If preheat power drives your roast significantly above the profile curve then the roaster will never get a chance to follow the curve because the "heat too fast" error will stop the roast.

The default setting for preheat power is 1050 Watts to achieve 110°C at 60 secs. If you need a slower or faster start to the roast, adjust proportionately then collect and examine roast logs. You are looking for the roast starting out on the profile curve, not above or below the curve.

The maximum value for preheat power is 1400, but it is probably wise not to exceed 1200 to allow for variations in room temperature and mains voltage.

Noob
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Re: Dealing with "heat too fast" error

#116

Post by Noob » Fri 07 Jun, 2019 9:36 pm

I just got the "Heat too fast error" running the built in profile for 110g of beans. It was roast #2 straight after the first. The starting temperature showing on the screen was about 40 degrees.
Whats going on there?

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Re: Dealing with "heat too fast" error

#117

Post by Noob » Fri 07 Jun, 2019 10:01 pm

Here's the log...
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log0015.klog
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Re: Dealing with "heat too fast" error

#118

Post by kaffelogic » Fri 07 Jun, 2019 11:16 pm

Thanks for showing me the log. We are seeing logs from people doing immediate follow-on roasts where the roast gets off to a rough start with some quite big rate-of-rise oscillations. In this case there was an upswing that exceeded the threshold for "heat too fast" detection. This will need to be addressed by a firmware update, however that will take some time to develop. Meanwhile we are going to have to advise waiting about 5 minutes between roasts to allow the roast chamber to cool.

Lenbok
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Re: Dealing with "heat too fast" error

#138

Post by Lenbok » Sun 30 Jun, 2019 12:09 pm

Thanks for this post explaining the preheat side of things. I bumped into this for the first time today when trying the default profile with some Indian "Monsoon Malabar" beans that I'm guessing must have quite a low moisture content, as they are very light (in weight and color).

I dropped the preheat to 750W and it happily completed a roast (from the look of the log I could probably lower the preheat a little more as it's still a bit above the target during the initial phase).

Cheers,
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log0033.klog
preheat 750W
(65.17 KiB) Downloaded 112 times
log0032.klog
heated too fast
(6.07 KiB) Downloaded 125 times

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Re: Dealing with "heat too fast" error

#140

Post by kaffelogic » Sun 30 Jun, 2019 12:53 pm

What you are doing will certainly work, but you may find it simpler to just increase the load to 120g. Monsoon beans (and incidentally also de-caff) are less dense so if you use the measuring scoop provided you will end up underloading. Once you get the weight right you should be able to get away without altering the profile settings.

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