1000 Roasts

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After 250 kilos (551 pounds) I think I have a handle on the home coffee roasting cost profile, how to disassemble and more importantly reassemble the HotTopUSA KN-8828B table top drum roaster. I am two days short of the Fifth anniversary of home roasting but admit to being a little confused over the exact age of my roaster given all the parts replaced. Over the course of 5 years I learned that home roasting is the most economical way to enjoying coffee roasted to your tastes. I also learned (once again) that proper, timely cleaning and maintenance will extend the machine’s useful life.

Good vendors make good coffee. I find the level of service from Michael at HotTopUSA is well above excellent. He is both timely and his recommendations are well described in text and pictures. He seems to always know exactly what needs to be done. We are currently in the process of trying to figure out why the motor and drum sporadically do not engage at the start of the preheat cycle. This has been a more frequent issue over the last 200 roasts but only once did it fail to start prior to the start of the roasting cycle. Additionally, although not an issue for me, the warning alert at 356° F works less than 5% of the time now. Neither of these issues have impacted the ability to roast beans nor have they effected the overall quality of the roasts.

Nothing that you can do will fix bad beans. Like everything else, start with quality ingredients, use sound equipment and follow proven technique. Sweet Maria’s has supplied my green beans from the beginning and I have no interest in looking anywhere else. Their write-ups on different coffees are spot on and their prices are more than reasonable given the high, consistent quality of the green beans.

Keeping a roasting log makes it easier to track roasts and maintenance steps to make sure they actually get done:

  • Every fifth roast, clean the viewing glass and vacuum out the roasting chamber.
  • Every tenth roast, clean the roasting drum in the dish washer.
  • Every twentieth roast, replace the rear air filter.
  • Every hundredth roast, replace the top air filter.
  • Every 6 months to a year, clean the rear fan and motor.

I have heard that many will clean their rear filters and reuse them or use something other than the official HotTop filters. I was cleaning my filters for a while but after about 100 roasts the rear fan went wobbly with a build up in soot and chaff and needed replacement. What I saved in filters, I spent on a new rear fan. Whatever you decide to do, focus on life cycle costs and avoiding trying to manage short-term costs. With a little care you can easily attain a cost point well below coffee-house prices.

Wear and tear is a natural consequence from operating machinery. Part of the variable costs in roasting coffee, in addition to the filters, are the various replacement parts. To date I have replaced:

  • Main Fan
  • Cooling Tray Base
  • Bean Ejection Solenoid
  • Panel under Chaff Tray (Minor little fire)
  • Bean Ejection Chute (twice)
  • Fusible Link
  • Heating Element
  • Temperature Sensor

The panel under the chaff tray and the main fan I chalk up to operator error, the balance is normal wear and tear. The design of the bean ejection chute has the roasted beans landing on the bottom section then falling out onto the cooling tray. Because I primarily dark roast our beans, they are frequently oily and this residue builds up on the ejection chute. When ever I do a decaf roast, given these beans are much lighter per bean, they may stick on the bottom of the ejection chute causing a build up of hot roasted beans back up the ejection chute into the roasting chamber creating a potential fire hazard. I have found that cleaning the ejection chute is of minimal value so whenever the beans start to stick I order a replacement ejection chute.

The comments and advice offered when the roaster turned its 700th roast are still valid. Since then I installed an Intertek Model P4460 Kill A Watt electricity meter to see just how much electricity was used during a roasting cycle. The answer was not that much, a roasting cycle averaged .256 Kwhs or less than 2 cents.

Following is a summary of my costs over the last 5 years. I used average electricity consumption measurements over 50 roasts as a proxy for the 1000 roasts along with my current incremental rates.

As should be expected the majority of the costs stem from the green beans, with the prices in the chart above being the average price paid for green beans over the last 5 years, adjusted to reflected the weight lost in roasting which approximates 20%. It should also be noted that I bought 10 pounds of Sumatra Mandheling Aceh Triple Pick last June and the actual roasted cost is currently $9.92 per pound. The average roasted bean costs in the chart above is effected by the variety of bean purchased, the quantity of beans purchased and the current market conditions.

I believe the major take away from the chart above is the amount of attention you should pay to routine maintenance and cleaning with an eye towards managing the repair costs.

I probably have 500 hours or more invested in roasting beans. I have the time, I find the results suit our tastes quite well and that it has been a worthwhile activity. I also have an indoor area devoted to removing smoke and cooking odors so I am able to roast regardless of the weather or time of year:

Barbecue Grill, Coffee Roaster and twin Bradley Smokers waiting for custom hoods and fire suppression installation.

Barbecue Grill, Coffee Roaster and twin Bradley Smokers waiting for custom hoods and fire suppression installation.

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