I have a Hottop P that I have been enjoying for a while now. During the last few roasts though the result has been terrible, it's like the beans are baked instead of roasted.

I have attached a copy of my log. Each step is quite similar to normal until late in the process. I never hit second crack, even after a long time and high temperatures. Any idea what could be wrong?

Here are some ideas off the top of my head:

- Replace the rear filter.
- Clean the temperature sensor inside the roasting chamber.
- Disassemble and clean the entire roaster.
- Be sure all internal connections are tight and clean. Disconnect and reconnect everything you can get to. One connection that can be problematic are the two spade terminals at the back of the temperature sensor.
- Be sure the black filter on the top of the machine (behind the top grill) is in place.
- Remove and check the rear fan. As coffee particles and oils build up on the blades it dramatically decreases its efficiency.
- Check the voltage at the outlet you are using, or try another outlet on a different circuit.
- Try programming it for the max time and temperature possible and running a roast with no beans to see if it reaches the correct temperatures.

Once a year or two (depending on how much use my machine has had or how dirty it looks inside) I disassemble my machines and clean them. All non-electronic parts get cleaned in TSP or equivalent). If you check the Hottop USA website(http://www.hottopusa.com), there are all the step-by-step instructions you need to do that. If nothing else, it's a good way to get all the stray coffee beans and chaff particles out of the roaster.

if none of that helps, let me know and I will continue guessing....

I agree with checking the rear filter. I had an old rear filter in my Hottop P and while the roasting profiles weren't affected the taste really was. The roasts tasted terrible until I cleaned the filter.

I've heard as well that roasters running with heating elements are very voltage sensitive. Just a bit of a step down in voltage or considerable voltage fluctatution could affect the roasts as well. Have you tested your supply voltage?

Topic moved to home roasting forum by moderator

Randy G. wrote:
- Replace the rear filter. DONE
- Clean the temperature sensor inside the roasting chamber. DONE
- Disassemble and clean the entire roaster. DONE
- Be sure all internal connections are tight and clean. Disconnect and reconnect everything you can get to. One connection that can be problematic are the two spade terminals at the back of the temperature sensor. DID SOME, NOT ALL
- Be sure the black filter on the top of the machine (behind the top grill) is in place. DONE
- Remove and check the rear fan. As coffee particles and oils build up on the blades it dramatically decreases its efficiency. DONE
- Check the voltage at the outlet you are using, or try another outlet on a different circuit. TRIED ROASTER AT 3 DIFFERENT HOMES
- Try programming it for the max time and temperature possible and running a roast with no beans to see if it reaches the correct temperatures. SEE BELOW

I eventually gave up on the roaster after trying several suggestions, including those above and some by HottopUSA. I had a great local roaster nearby and have been buying beans since. Now I have moved however and getting good beans is more difficult. I need to get the Hottop up and running again!

In addition to the above I also made sure to align the heating element parallel to the drum. I also made sure there were no scratching / parts touching as the drum rotated.

I ordered a fresh batch of greens which roasted yesterday. I programmed the machine to the highest target temperature for each segment. In addition I shortened the time within some segments to try to ramp up the temperature as quickly as possible.

I used 250 grams of Sweet Marias Monkey Blend. The total length of the program was 15 mins 30 seconds. At the end I added 30 seconds for a total roast time of 16 minutes. I have attached a picture of the roast temperature at the end of each segment (in addition I recorded a temperature of 201 degrees C with 4 minutes left on the timer, not sure how important the sampling rate of data is here...).



First crack started with 02:35 left on the timer, approx 207 degrees
First cracked slowed down with 01:07 left on timer, 213 degrees
Second crack started with 00:50 left on timer, 216 degrees.
I ejected the beans after adding 30 seconds (1 minute 20 seconds after second crack started). Temperature was 219 degrees.

None of the cracks really took off though, especially the second one since I ran it that far into second crack it should have been really popping! There was no visible oil on the surface after 24 hours. The beans had a wrinkled finish and they don't smell like a good roast should.

If I understand your program correctly, you have zeroed out the time for the last leg. This is why you are stalling out. Segment 7 only goes to a max of 414F (going by memory here...) and will actually cut off the heaters at 410 with the residual heat taking it a little higher. Your 216C (421F) is barely through FC and a long ways from the Vienna roast that you are probably shooting for. You are baking the beans by just sitting at the 414F limit with the heater occasionally cycling on, but mostly sitting at off.

Cut back on segment 7 to about 2 minutes and put a full 3 min on Seg 8 with the temp at the max limit. You will need to monitor the roast and eject about 20 seconds into 2C. Don't worry about the weak sounding 1C, that comes from the blend where different types of beans crack at different temps so you won't get the same rapid cracking that you get with a single origin bean.

Rick

No, the time after each segment is the time left once that sement has finisghed. So when I finish segment 7 there is still 3 minutes of segment 8. On the roast I did just prior to this one (slightly different profile but not by much, I used the auto profile for the fanspeed instead of reducing it to 1) I watched through the looking glass the entire last 5 minutes. The heating element never shut off, it was on all the time.

OK - now I understand! If you can see the coils glowing you should have plenty of heat. The time to get to first crack is about right as well. I've modified my HT so that I can reduce the power near the end of the roast and even with about 40% of the power I can still get well into 2C without any problems.

With all the work that you have put into your machine, the one thing that is most useful is a sensor for bean mass temperature. I drilled a hole in the back wall below the HT sensor and fed the TC wire through a small tube. Others have put a probe through the filler chute cover with good success. Either way, you get a far more accurate indicator of what is happening with the roast than you can with the HT readings.

I didn't like Monkey blend when I tried it and for trouble shooting a roaster I would recommend a wet processed SO rather than a blend. These are the most uniform beans and will give much clearer definition of the cracks.

The only other thing I can think of that has not already been mentioned are the air vents beside the heater coils. These can get loaded up with dust and carbon and keep the air from being routed through the hot coils. If this happens, the air will be drawn into the drum through the top filter and could be cooling the beans. It is a long shot, but it sounds like you have checked all the easy stuff! Good luck.

Rick

Thanks for helping!

Is the heating element always running at 100% on the Hottop P? I figure the most likely culprit is either the temperature sensor or the heating element itself... If the heating element is either on or off I would assume its not the sensor and that the heating element is to blame.

Agree?

Yes, the power controller on the HT is a simple on/off and due to the thermal overshoot, once it turns off it will stay off for 30sec or more. Generally the heaters are only turned on again when the program moves to the next segment. The "B" has a power level adjustment which is a big improvement. I added a circuit that lets me switch in a dimmer control so that I can slow things down once they start cracking.

The temp sensor can go bad (I replaced one) but unless you are hitting the maximum temp in a segment causing the heater to turn off it should not have any effect on your roast. It could be a safety issue if it reads so low so that the automatic termination doesn't work but other than that it will just show you a bogus temp on the display. Note that the sensor and back wall can get coated with black tar which will change the reading over time. Cleaning it off nice and shiny makes a difference, but unless the heaters are being controlled by the reading, it should not effect your roast.

Your heater elements are also very likely to be fine since you are reaching first crack in 13 minutes. The time between the start of 1C and the start of 2C is less than 2 minutes which is FASTER than you want (and the reason I use the dimmer). The HT temp readings are also reasonable for the cracks, even if they are a bit different than you may be used to.

Without a bean probe to see what is really going on with the roast I am out of ideas. Your results sound like the beans are baked from a stalled roast, but the data that you show does not indicate that. The roast is a little slower than I like. My batch size is usually less than 230g and I even go down to 160g for some coffees just to get the time to first crack down but then slowing it down with the dimmer after that. But if you have been happy with the 250g roasts, you should be able to repeat them. And the smaller batch size matters more for light roasts than dark roasts. Sorry amigo!