Popper Heat Settings, Roast Temperatures and Roast Profile Tips

A chart of the Popper roast chamber temperature and heat coil power based on the setting of the heat knob, as well as some new tips for roasting!

We have been working on mapping out how the position of the heat knob impacts the temperature in the Popper roast chamber.

This might seems straightforward, but it has been hard to relate the readings to the real world roasting experience. These temperature settings are based on running the roaster empty, and measuring the hot air as it enters the roast chamber. They are not the temperatures measured with coffee in the roast chamber.

Nonetheless, while we continue to improve on roast profile ideas, with coffee in the roast chamber, it seems useful to share this information. The settings were done by an engineer at the factory and I corroborated the temperatures on multiple units here.

Two things to be aware of though. How you measure temperatures, and how a probe is placed matters greatly. That’s why I have been more interested in charting bean temperatures in roasting. But bean temperatures in an air roaster come with additional complications, because they vary by batch size, type of coffee, and how much a probe is actually reading a contact temperature with a bean versus the hot air stream.

The second surprise here is that in the final production unit of Popper, the roast setting between 2 and 3 isn’t meaningful! The power to the coil is the same. This was a surprise to me, even though I had tested the difference in prototypes. And I need to change our “initial roast recommendations” in the literature based on this. If you start at roast at 2, you might as well start it at 3, full heat! In fact, I now think it is best to roast initially at 1:30 on the heat dial (and fan on High … always start roasts on High fan speed!)

On the flip side, the fact that the heat dial has a “dead zone” between 2 and 3 is no shocker either. Any electric appliance with a digital or analog dial like this is going to have a lack of uniformity in the measured effect of incremental change. On an electric stovetop lets say, the difference between a setting of 4 and 5 will not correspond in temperature degrees to a change between 6 and 7. The reality is no control of this kind produces uniform results across the range. (And in fact a gas valve is no better, but at least you can “eyeball it” by looking at the flame!)

So please consider this chart as a starting point to better understanding the process when roasting with Popper!

Popper RoasterLow Fan SpeedLow Fan SpeedHigh Fan SpeedHigh Fan Speed
Heat Knob PositionCoil Power (W)Temperature (F)Coil Power (W)Temperature (F)
9:00082.5082.5
9:30082.5082.5
10:0042.792.448.692.4
10:30113.7139.8118130
11:00397195.8403187
11:30397196403190.9
12:00666277672267
12:30925365930351
1:0010984361106418
1:3010964451102419
2:0011734651177445
2:3011734651176445
3:0011734621177445
Popper Coffee Roaster Chart of Heat Knob Settings and Corresponding Wattage and Temperature Rev 10/2021

Popper Roast Profile Tips

Roasting with Popper means finding out what works for you … the machine doesn’t have programs or make roast decisions for you. (If you have one I am sure you know this already!) It’s a tool and of course, tools can be used in various ways. So it’s good to learn by experience, your own experience, but here are some general tips that supersede what comes with the printed material with the roaster:

  • In our opinion, a good starting roast profile is 90- 100 grams (weighed out), with Fan set to High and Heat set to about 1:30 on the dial (ie, 1:30 on a 12 hour clock face).
  • Coffee should rotate initially, even if it is quite slow, and pick up speed in the first 30 seconds – 1 minute
  • You might hear the start of First Crack as early as 4 minutes into the roast (which would read 6:00 on the digital timer). But first crack should be slow and extended at these settings. If it is rapid, reduce heat to 1:00 on the heat knob.
  • In the middle or toward the end of first crack, reduce the temperature to 1:00 or 12:30 on the heat knob.
  • You can finish out the roast this way, or if you want further bean development, headed toward second crack, change the Fan Speed knob to Low setting. This will increase the roast chamber temperature and help the roast develop toward 2nd crack
  • If you want a darker roast, add more time. For a few snaps of second crack (where I personally like my espresso), add time. I usually end up adding 1 minute -2 minutes.
  • The way of approaching darker roast levels will avoid the “high temp thermal cutoff” which happens at 465 f. When that happens the roaster loses temperature as the heat power coil is off for about 20 seconds. In fact, using a slow development approach, which avoids the temp cutoff, is also a far better roast profile than one that pushes too much heat at the coffee too quickly.
Popper Coffee Roaster Chart of Heat Knob Settings and Corresponding Wattage and Temperature Rev 10/2021
Popper heat Dial With Paper Label.

8 Responses

    1. Thanks for the question … it isn’t a typo, but I know instructions can get confused because the way we refer to the heat knob settings as a clock face. So what it is saying is to start the roast at about 1:30 as if, when facing the roaster, the heat knob is a clock face with a range from 9:00 to 3:00 with 12:00 at the midway point. And depending on how the 1st crack is sounding, reduce the heat to a setting that would be 12:30 to 1:00 (again, heat know as a clock face) when you are hearing first crack. None of these are references to roast time

  1. lets say i roast 5 batches of the same coffee,exactly the same , then let them rest. 24 hours later i brew 1 batch. can i expect to get a little bit different flavor on the next batch that will have been rested for 48 hours and 72 etc?

    1. Hey Kevin,

      Great question. The coffee will continue to off-gas CO2 during the period of rest between roast and brew, but I honesty wouldn’t expect a huge change in flavor between just a couple of days for most wet process coffees. We do recommend longer resting periods for some of the coffees with more outlier flavor profiles – Sumatra, dry process Brazil, etc – and that’s because there does seem to be a perceptible difference in flavor between day 1 and day 3, for example. The flavors seem to coalesce with the extra couple days rest, whereas they’re much more disparate straight from the roaster, and even at just 24 hours.

      For me, part of the fun with these smaller batch size roasters is having that flexibility to taste different batches over time, or slightly different roast levels, etc, and get a better idea where the proverbial ‘sweet spot’ lies, or just to see if you do indeed taste any differences.

      Hope that helps. Let me know if I can answer any other question!

      -Dan

  2. If I wanted a light roast, at what point should I initiate cooling mode in relation to first crack? At the start, middle, end? Thank you!

    1. Hey Jim,

      How soon you pull the batch after 1st crack is underway, will depend on how hot the roaster is. Generally speaking, stopping the roast toward the end of 1st crack should yield a lighter roast level (roughly City). If your Heat dial is at like 2:00 position, you are likely to hit 1st C within the first 4 minutes, and I’d look to start the cool cycle around 1:00 after the first audible snaps. I tend to keep my Heat settings around the 1:00 position, which gets me 1st Crack around 5 minutes, then pull my roast after 1:30 more.

      Hope that helps. Feel free to reach out with any other questions.

      -Dan

  3. The Popper seems ready-built for an Arduino-based modification to control roast using a temperature probe. There is a 2.5mm pitch rectangular connector on the power control board to which the Arduino can be attached to drive the heater and fan triacs and have access to onboard 200mA 5VDC power. If you want to encourage this effort, you might consider publishing schematics as well as the make and model of that connector.

    Otherwise, it seems like a firmware change to the Popper control board could make temperature control linear with respect to heater knob orientation. The usable range of that knob is currently very limited.

    1. Thanks a lot for your thoughts on this James – I myself haven’t done the modification but am eager to … honestly I was hoping someone would share some insights on this or offer a guide. I think some new approaches coming from the home roasting community could really open up great possibilities for control of the Popper. I can look into publishing more info to assist with this, but have been dealing with some resistance from the factory engineers over transparency on this. I’ll keep at it though.

      I am definitely interested to tune the heat knob function so it covers the useable range better!

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